These videos really are great. As well as being clear and methodical, they don't miss anything out. As a result of following these I've now got a flat, lime-plastered wall that looks fab.
The sequence, the equipment descriptions, the timings and the small tips about the various pitfalls are excellent guys. Clearly you are craftsmen, but this has given me the confidence to have a go at all of the internal cob walls in my French country cottage. I was going to batten and board out the walls as I was worried about getting a decent finish surface on the cob walls, but if I can follows your guidance I'm now more confident I can do it proud. Thanks for sharing
Thanks for this Mr Wye. I have used your stuff on many occasions because your materials are always good and very usable. Instead of using metastar I prefer using a brick dust. Harling is good and effective but if possible I prefer to use a mortar sprayer with a full sized compressor to do a thin 1st coat which I then blat it on at about 90 -100 lbs per square inch. I also use a wider tined scratcher but have cut away every other tine because they were too tight together, I also like to slurry area's before I scratch because it helps to bind the two surfaces together. Many architects and builders cover their cob surfaces with metal mesh fixed with screws & plugs, resins or cone headed twisted nails but this isn't necessary if you do a 1st coat with a harl or a spray that should be sufficient, it's all about the key.
I really want to learn this I have been in the building trade for a wile but something always pulls me towards lime and old ways buts the good ways .. I am going to learn this :) Just got to keep watching and get the process in my mind .. thank you to the guys teaching us what a pair of pros :)
Thanks much appreciate the video and your responses. Breathability and the way lime kill off bacteria fungi and viruses makes it a superb material. Looking at this as thinking of building hempcrete which has a friable surface so needs a lime breathable finish. Has long loved the victorian homes I lived in with set plaster walls and lime plaster wedding cake ceilings within handmade clay brick and lime mortar walls.
janet lesley Janet Im wondering if using Hemp in traditional plaster would be beneficial inbthe project i am currently inder going.Some origional Lathe work walls that need attention and some fine Oak timber beams in a Georgian period 1790 Out house
This is by far the best video on this subject I have found, you are true craftsmen and thanks for sharing. I am trying to fix up some damaged areas on my heritage listed Georgian/Victorian building in Tasmania Australia. I would really appreciate some assistance in actually making the 'lime putty' or something similar using locally sources material. I can get the sand and hydrated lime from the hardware shop. Can I email you guys for some assistance? I can also send some pictures to show you what I am doing. Cheers.
Great video. It would be great to get a little more detail on how much to let each coat firm up before going on to the next, or before floating, and how much pressure is being applied for each coat. I know that in a video it would be hard to get a clear picture of the firmness of each coat at each stage, but that's one thing I can't pick up without being there "in person". Speaking of which! Have you ever considered offering a multiple-day course on lime plastering, spanning enough time to see how the stages tie together? Definitely worth building my next holiday around it!
Great video, some top skills on show! I'm working on my 1890 (ish) terraced house and looking to redecorate one of the bedrooms. Removing decades of wallpaper has left a very rough, pitted surface unsuitable for painting. Is it a good idea to simply do a top coat using a lime plaster to provide a surface that could be painted, rather than taking the existing plaster back and doing more coats?
Stew Murray Thanks Stew! This video shows the full build up for internal lime plaster work but there are methods of renovating existing plasters to 'make good' without hacking off all of the old plaster. Provided the existing plaster is sound and really just needs an additional skim, it can be primed with a low acrylic primer (we use Bayosan DG27 www.mikewye.co.uk/product/dg27/) before skimming with something like a 3:2 lime putty plaster www.mikewye.co.uk/product/lime-plaster/. Whilst a thin, painted coat of the low acrylic content may sacrifice a little of the vapour permeability, it enables lime skimming onto a range of surfaces without the need to apply the full build-up of coats as shown in our video. I hope this helps. Ryan
Just found your channel 👍 Excellent video 😎 I've been Plastering for 25+ year's. And have recently started working for myself. And have started coming across having to use breathable materials. Lime. But haven't done a great deal of lime. And when I have done. I've never mixed it up. I'm the one who puts it on the wall 😉 so would be very grateful if I could ask you a few questions about rendering with hydrated and hydraulic lime. Great video 👍😎😎
Hi Neville. Thank you for your kind feedback - much appreciated. We're more than happy to help with any questions you have but you may find it easier to do so through our online chat via our website www.mikewye.co.uk, or by email sales@mikewye.co.uk, or on the phone 01409 281644. We're here Monday to Friday 08:00-16:30 (GMT).
Great video, thank you. I grew up around buildings with lime construction. There is something so serene about the texture and feel of these buildings. I would love to incorporate lime plastering on the walls of the farm house I am going to build in Dominican Republic. Is there a video on lime mortar preparation? I have videos from other folks, but would love to see how the mortar/putty was mixed (that was used in this video).
Cave Man Thank you for your comment. In our early days we used to mix lime mortars and plasters on a smaller scale but sadly we don't have any videos of the process. These days we mix in larger agricultural mixers so not sure how relevant a video of that would be. We're happy to answer any questions you might have though.
+Cave Man When I was a kid plaster walls were built up on wooden lathe strips and it was very strong though prone to micro cracks. Frequently hair was mixed in [I heard horse hair but no matter] to reinforced the plaster. Now I presently live in the DR and am thinking of using coir fibre from coconut husks to strengthen and reduce cracks.
This video is quite wonderful. I'm located in far west Texas close to New Mexico and looking to use lime plaster on exterior and interior adobe construction.
A great video, very informative. What type of paint to you recommend for lime plaster on internal walls? Does regular water based emulsion still provide adequate breathability?
+Voodoo Melon Apologies for the slow response. The key thing to look for when choosing a paint is that they do not include acrylics. Modern water-based paint often still contain acrylic which forms a restrictive layer over the plaster. Thankfully, there are many paints on the market which allow excellent vapour-permeability (breathability) in a good range of colours. These include: clay paint, lime paint, natural emulsion, silicate paint, and the more traditional distemper, casein paint and limewash. Take a look at our website for details and colour charts on all our breathable paint finishes www.mikewye.co.uk
Thanks, Mike. I'm really looking forward to having a go at this. I'm tempted to practice on the inside of the garage first. I'm guessing that concrete blocks from the 1980s aren't exactly breathable, but at least I won't make a mess of the walls inside the house trying it for the first time there!
Clean the area and damp down, apply a small amount of material and float/sponge over as it dries back. You may find a finer sand mix easier to blend but it can be done with the standard mortar
metacaolin question: do you add 7:1 ratio to the lime putty or 7:1 ratio to the entire mortar mix, I remember reading somewhere that metacaolin is highly reactive and you only need to add 2 to 5%, adding too much may cause shrinkage issues as well. on the other end of the spectrum brick dust is of low pozzolanic reaction and you can add 1/3 of the aggregate (25% of the mix) up to 100% of the aggregate can be replaced with brick dust, depending on what final properties you are trying to achieve. rising damp issues, etc...
Fabio Bardini, we add the metakaolin to the mortar at 1:7. The addition of pozzolan is an interesting and broad subject which has recently been revisited by the Building Limes Forum in the U.K. as the theme for this year’s annual conference. We try to keep our finger on the pulse with all new developments and research, however we’ve been using a gauge of metakoalin with traditional mortars in these sorts of volumes for 25 years without any resulting shrinkage. Many other pozzolanic additives can be used but may not be easily accessible, can be inconsistent in their reaction, or can have an unwanted effect on the mortar colour. We’re happy to discuss this further if you’d like to call our office, or email us at sales@mikewye.co.uk
Great videos! I was wondering if you had some more information on that harling coat though. I'm currently struggling with some old, extremely thirsty brick walls. I managed to get the first coat on nice and flat and soaking the wall gave me just enough time to do it. However... I applied the my first coat months ago and now it's bone dry. I've tried soaking the walls again but the finish coat, I supposed because it's much thinner, just keeps drying out too fast... by the time that I'm at the bottom, the top is pretty much dry to point where I can't work it anymore. Fighting it with a wet sponge helps a bit but so far I've only done small walls to test. This method is not going to work on my bigger walls... I'm wondering, could the harling coat help before applying the top coat as well? How much pozzolan might I add? Thank you for your help!
Sorry for the delay in replying. Are you doing a full internal lime plaster build-up with a harl coat, scratch coat, float coat, and skim, or is this an external render application? If so, what stage are you at now? If the coats are applied "green-on-green" then the previous coat shouldn't have dried out so much that it's very thirsty like you are experiencing. As the last coat you applied was done many months ago then you may benefit from another harl coat (assuming you are at the float coat stage). I'll presume that this is an external application given that you've asked about the addition of a pozzolan. We should safely be clear of the risk of frost now so early spring is a great time for render applications to give plenty of time for carbonation and strength gain before the winter. With that in mind, and given that you have very thirsty walls, I wouldn't go any more than 1:8 pozzolan to lime render by volume. There may even be a case to reduce this to 1:10 provided that the area isn't particularly exposed or vulnerable. I hope this helps but feel free to give us a call on 01409 281644 if you would like to discuss. Best of luck with the project! Ryan @ Mike Wye
Could I use a ultra fine hair brush at the last sponging stage or after? Plus would memory foam have a similate effect to a more dense sponge.Im preparing to Lime plaster the interior walls of a Georgian period Out house,many thanks
Nice informative video , in many parts of India too, people who build traditional with help of lime, n plastering too is done with mixture of sand ,clay, n lime, One more thing if u want to build one of the wall of stones of ur house then try to find out how indians use to build mortar with help of jaggery,black gram lentils, Fenugreek seed, n some other sort of bitter tastes liquids to keep away termites
Hi love the videos thanks, i have a question can you do sections at a time, Example I have a Large external wall I need lime rendered, in planning to do it myself, could I do the wall in 3 stages with no bells , just flat and do section to finish coat different days?
Hi Mike, you could do the harl and scratch coats in stages but you would need to try and complete the float coat in one (it's very hard to disguise joins in the float). If there are down pipes, that would be a good place to stop and start.
Assuming that they are slight imperfections then the paint or limewash itself can help to improve and disguise blemishes. If the patches are beyond fixing with a paint then it may be possible to feather in a fine lime putty filler or put a very thin skim over the entire area if the plaster is still relatively green.
lozington95 Thanks for your kind feedback. We’ve just revamped our Practical Guide which can be downloaded as a pdf here www.mikewye.co.uk/product/brochure-practical-guide/ or you can request a printed copy 👍🏼
The soil around me is acidic. Seeping water is bound to have a low PH. I bet lime-based mortar will get eaten up pretty quickly and efflorescence will develop at the joints on the inside wall. Any thoughts on how to prevent it? Also, would adding the "potslan" (spelling?) help keep it water proof?
Although a wet lime mortar is highly alkaline, once carbonated it becomes pH neutral. As long as the walls don't become saturated and if both internal and external sides are lime the wall with breathe and should not cause any problems inside. The pozzolan increases compressive strength and helps to protect from frost and generally makes the mortar more durable.
Hi, no we manufacture lime putty here so we use that as it provides a richer mix but hydrated lime is a dried version of this. We use a ratio of three parts sand to one part lime putty by volume.
In Korea, In my opinion, Not quick lime But Hydrated lime. in these kinds of cases, traditionally use Hydrated lime(quick lime + water = Hydrated lime). lime putty, lime mortar etc...
Thank you Carey. Totnes is a little further south than we usually cover but not completely out of the question. If you have a project you’d like quoting for them we can also put you in touch with suitably experienced and knowledgeable trades people in your area.
Ah-ha. I wasn't sure if you were nearby because I detected a Cornish/Devon accent. Considering I just have one internal wall (approximately 2.5 m x 4 m) - and one external length of wall which is only about 4 m², it probably is not worth your while coming all this way down if you are "Up-country". It would be useful if you could recommend somebody in my area. Congratulations once again on your incredible work - hopefully this Will prove a good platform for you to get more work in your area.
Carey Marks you’re absolutely right about the accent. We are in Devon but in the north so it’s not always cost effective for us to travel for such a job. If you drop us an email to sales@mikewye.co.uk then we’ll give you a couple of contacts who can help. Thanks again for the kind feedback. Regards, Ryan
I have an old house, with lime plaster on the interior. The lime is pretty old and degraded in some little areas, but I know that lime helps the old walls breathe and i don't want to change it with cement based plaster. My question is, is it good, and will this type of plaster sustain a clinker brick finish (1-2 cm thin bricks applied on the wall via a special based adhesive) that I wish to apply to it? Or do you recommend an cement based plaster?
Hi, you would need to check the adhesive for breathability as it would be covering the lime. Also any cement based adhesive will be a lot stronger than the lime and may cause delamination (especially on old lime)
So the harling mix is 3.5:1 but it's really runny. I'm guessing that's because you added so much water. Doesn't that make the mix pretty weak? How will it cure properly and be strong? Or is it just supposed to be there to prevent sucking as much with the scratch coat?
Thank you so much for these videos. For an amateur like me they are super informative and helpful. I do though have a few questions I wonder if you could help me with? I’m in Portugal and have a early 1900’s stone walled house and really want to use traditional methods to do her up.. my builders are of course pushing cement…. When I suggested lime, they said Yeh sure, but we HAVE to add 1cement to 1lime to give it strength otherwise it’s like powder and will just mark with any small bang… Is this true? My other question is, do I have to add hair or any other type of fibre? Or can I just do the lime sand mix? It’s hot here and I’m wondering how to help it dry properly(not too fast)? I see you splash water on some of the layers but how do I control the final plaster one? What’s the difference between lime mortar and lime plaster? And what sand do you use? Is there like a grade to go by? They are using quite tough sand here which I don’t like but they say after this one there’s on,y one that’s ever do slightly more fine, which I don’t think I could ever achieve these smooth finishes with? Thank you so much! Hugely appreciated if you find the time x
Thank you for your kind comments. Our mixes are one part lime putty to three parts sand by volume. This is a traditional mix that air dries and carbonates. The lime that your builders are referring to would be hydrated lime (a dessicated lime putty) that is used as a plasticiser in cement mixes. For a compromise you could use NHL (natural hydraulic lime) at the same 3:1 by volume ratio. This is very common in Europe and easily accessible. The NHL is a dry powder that will give a chemical set with water rather than air-drying. It's a bit of a compromise. Water and protection from direct sun are the main ways to control drying. Our mortars and plasters differ slightly in mix ratios but essentially it is the aggregate size that makes the difference.
@@MikeWyeLtd thank you so much for you quick get back, much appreciated. Hydraulic lime, that’s the one! They still want to add cement to that though which is annoying, 1 lime to 1 cement then sand.. as they say it will be super soft and any little bang will make a mark on the wall. As for the controlling of drying time, I’m slightly worried about this as they they will do it when it’s warmer and Portuguese sun is HOT whatever the tone of warmer months.. so I’m worrying it might dry out too quickly. Should I spray it every day or something to help it along? Thank you so much again x
@@leafside A 3:1 mix of NHL3.5 and sand shouldn't be too soft, the lime putty renders are softer than these and still take a fair bit of abuse. Yes regular damping down will be beneficial.
Just moved into a cob cottage that has been cement rendered outside & inside on the ground floor. Silicon injection damp proofing to prevent rising damp. Is it worth using lime mortar internally on the first floor.
kate herd, our apologies for missing your comment a few months a go.....not sure how that happened. There can be some real benefits in using lime plaster to help with moisture management and for the benefit of the property. However, we always encourage breathability to the outside first wherever possible. If you are considering improvements or need to replace renders or plasters due to dampness or damage then it may be wise to address the external cement render first, finished with a breathable paint.
Hi David. Thank you for your positive feedback. The application for an external render would be almost identical apart from a couple of details: The lime plaster skim would be too weak and vulnerable for external use and therefore the top coat would be a finished unhaired coat rather than devil floating it as shown here. We also recommend the use of a pozzolan additive for external works (particularly if you're in the UK given our climate!) to bring on an initial strength gain and protect from adverse weather and frost in the future. Regards, Ryan @ Mike Wye
Ryan, thanks so much for the prompt and informative feedback really appreciate your help. Are you still supplying materials at the moment incuding delivery?
Internal traditional chateau walls are usually about 4 metres high and say roughly 5 metres wide. How do you get them straight and can you do the whole wall in one coating or do you need to do the wall in segments?
Are these plaster layers breathable? Is there a huge difference between these and external mixtures? Can these be painted with a natural paint? It's very rainy where I am as well.
+aghostdream Yes, lime render and plaster is breathable. An internal render is typically a 3 coat buildup, with 3/1 haired mortar as the scratch coat, 3/1 unhaired as the float coat, and then a skim of 3/2 plaster. Externally, it would be just the first 2 coats, and we would recommend a 3.5/1 mix, with pozzolan added for a more regulated set. For external use, we would recommend a silicate paint www.mikewye.co.uk/product/seciltek-silicate-paint-sp-01/
Hi Jemima, we have a customer with a static caravan that is moved fairly regularly. He has had some small cracks appear that he has patched in. If things are fixed well it may be ok but faults may appear when it is moved.
Hi, i'm getting ready to render my walls, can you tell me what type of sand are you using, is in rendering sand or building sand on all 3 coats. thanks
The backing coats use a sharp sand, typically 0-5mm with a good spread/blend of fine and coarse sized aggregate. Many merchants supply 50/50 sharp sands which can be a fairly safe bet if there’s any doubt. For the top coat lime plaster skims we use a kiln dried fine sand (kiln drying removes the majority of lignite therefore minimising marks on the plaster). The size of sand can vary depending on the fineness of finish required. For example, Georgian and Victorian town houses typically had smoother finishes when compared to 16th century cob and thatch properties. As a guide, somewhere around 0-0.25mm aggregate size will achieve a good result.
Hi HalfKatzBoy, It can all be used outside apart from the last plaster skim coat. This wouldn't cope with the weather as the aggregate is too fine and the coat too thin.
Hi. The process is fairly similar for rendering externally but the skim coat is omitted. You can find our external render RUclips video here: ruclips.net/video/1sjVSMypSvY/видео.html
I have zero plaster experience but recently motivated in the subject. Often heard about “preventing shrinking” here in your video too. what we want to preventing of? Why it is a necessary :) hope you don’t mind to explain :) thanks
Shrinkage can occur in mortars and plasters for a number of reasons but ultimately results in cracking which would need to be repaired afterwards resulting in weak areas and possible scarring. Causes of shrinkage are: *High suction from the substrate/insufficient control of suction in the substrate by dampening with water/use of primer etc. *An overly wet mix (the excess water evaporates away during curing causing the mix to crack) *Use of incorrect mixes/aggregates. For example, if you try to apply a fine internal plaster which is designed to be skimmed at 3-4 mm thick at 6-8 mm thick then the plaster is likely to shrink back due to the aggregate not being sufficiently large to hold its form. *Fast drying. If plasters, renders and mortars are subject to direct sunlight/heat/strong winds/high internal temperatures then they moisture contained within them will evaporate rapidly causing shrinkage. Mixes should be left to cure naturally and not force dried. If the external temperatures are high and/or there is prolonged direct sunlight on the area then the surface should be protected by using damp hessian/sheets/old curtains etc. Protecting the surface of external renders is advisable irrespective of time of year. I hope this helps.
Hi Peter. Thanks for the suggestion. We're gradually adding videos to our channel so will consider adding something along these lines in the future. If you do have any specific questions in the meantime please do email us at sales@mikewye.co.uk or call the technical sales team on 01409 281644
Hi, the mix ratio is 3 parts sand (sharp 4mm - Fines) and 1 part lime putty. For plaster we tend to use a kiln dried sand at a 3 part sand to 2 parts lime putty
@@MikeWyeLtd The sand graded up to 4mm is for the base and float coat only, correct? But for the two skim coats, since they are only 2-3mm thick I think you guys mentioned, then the sand would have to have a maximum particle size of 1mm, no? And for the skim coats do you still use sharp sand because I thought I read somewhere that one might want fine smooth sand instead of sharp to have a smoother final surface, especially for interiors, or? Wonderful video, thank you!
Hi Sameer, you can use an NHL (Natural Hydraulic Lime) either NHL2 or 3.5 mixed with sand, this has a chemical set with water. You wouldn't really want to accelerate the setting time but with this sort of lime it should be 'green hard' after 24-48 hours. A 3:1 mix ratio by volume is commonly used.
@@SD-bg4pm Many powder pozzolans, such as fly ash, brick dust and metakolin, have an effect on the mortar strength when added. We generally add them to traditional lime putty mixes to improve strength and offer better protection from frost. It's not necessary to add them to a hydraulic lime mix as the strength can be somewhat determined by the correct grade selection (NHL2, 3.5 or 5)
hey mate, I have a bag of quicklime and i also have a bag of hydrated lime i want to sample for wall rendering...what ratio do i mix the quicklime to water (slake) to make putty? and do i soak hydrated lime also into a putty, & if so what ratio to water is it? Super hard to find any information about the ratio to make putty...is hydrated lime able to be used for wall rendering?
Hi Johny. You really do have to be aware of the hazardous nature of quicklime if you're considering slaking it yourself. Our guys wear full face masks, body suits and gloves in a controlled environment when slaking. If you're comfortable you can manage the risks safely then we can give you a guide for the quicklime to water ratio by emailing sale@mikewye.co.uk Hydrated lime can also be rehydrated to make an inferior lime putty but we don't really recommend it be used as a binder for rendering. It's typically reserved for use as a plasticiser in a cement mix (6:1:1 aggregate:cement:lime as an example).
@@MikeWyeLtd hey mate thanks for the prompt reply. Yeah unfortunately i have to undergo the process of slaking myself. Im on an island in Indonesia and there is not such thing here of a bucket of putty let a lone even quicklime or hydrated lime bags...what im wanting to do (render my villa walls with a lime mortar) is revolutionary to these parts, mould is shocking here with the humidity. I found a mining company in Java that sent me a 20kg sample of both products (quicklime and hydrated). I have slaked a small quantality of the quicklime to check out the reaction, and do sample renders...im prepared mate, but unsure exactly the ratios. I will email you.
Hi Simon. We typically assume 12-15 mm material consumption for the scratch coat. Of course you may need to consider extra material for dubbing out and, in some instances, an additional scratch coat if the walls are particularly uneven. Regards, Ryan @ Mike Wye
@@MikeWyeLtd Thanks. I see on your website that two scratch coats are specified, is this optional? I.e. if you are happy for the walls to be uneven and retain their character, can one coat be used? We are specifying both internal plastering and external roughcast render.
Also - with the roughcast, do you add the aggregate to the harling coat, or do you add the harling coat then fling the aggregate at it? Thanks in advance. S
@@simonblunden6751 Exactly. If you have particularly uneven walls then you will likely need an additional dubbing out coat to bring the walls level before application of the float coat. If you would like to retain some character, or if the walls are relatively flat (such as brickwork or block) then an additional coat will not be required. Regards, Ryan @ Mike Wye
@@simonblunden6751 The roughcast/harl coat as shown in the video is a thinned down Unhaired Lime Mortar mix. We generally use something called Reabilita Cal CS (otherwise know as Consolidation Mortar) for harl coats these days as we can supply exactly the correct amount without having to work out how much of the Unhaired Lime Mortar to separate plus it is generally ready to receive a scratch coat in 24-48 hours.
@@MikeWyeLtd Thanks for posting this. So few videos about plastering over cob. I've got a question, if you have a quick second. I'm getting more cracking in my hair and scratch coats than I'd like. I think I'm having trouble getting enough aggregate in my mix. I aim for 3:1 but end up at best with 2.5:1 and sometimes closer to 2:1. I just can't work it when it is 3:1 -- it is very stiff and not at all workable. I don't want to add water, do I? My putty is about the consistency of toothpaste, so I think that's right. I'm not sure what's going on. In both cases, I've added 1 part hair (in my case it is 2"/5 cm lengths of shredded linen discard fibres). Any ideas? Thanks again for the resource and I'll understand if you don't have time to respond.
@@LowTechInstitute Thank you for the kind comments. It may be that you need to let the mix turn longer to increase the plasticity, it may also be that the linen is absorbing some of the water content. If this is the case you may want to introduce a little water but you're right not too much. I hope this helps.
okay .. thank you.. but its impossible to buy frome you guys.. shipment frome Australia to Portugal (no sence)... We also have Lime... and it would had to be done here.. thank you anyway
GuitarraLisboa1977 GuitarraLisboa1977 We’re a little closer than that in the U.K.! We also supply Portuguese lime (Secil Argamassas) but I’m sure it’s much easier for you to buy in Portugal. Kind regards.
Watched this video with the intention of learning how to plaster my old farmhouse walls.......but came away realising it really is a dark art, and I'd be better off getting a skilled plasterer in !!
There are no real trade secrets when it comes to the mix ratios used for mortars and plasters. Mix quality can be affected by the type of lime, its production process and the careful selection of sands. The mix you should be using is influenced by the type of work, time of year and exposure (where work is external for the latter two points). If you're ever in doubt, speak to your lime supplier (we assume Mike Wye, of course!) and they will be able to advise you.
It's absolutely possible to apply lime plaster or render to concrete block in the same way. This could be done for aesthetics, to match surroundings or from an environmental viewpoint.
Hi Ramona. Sorry for the delayed reply over the festive period. It's possible to apply lime over concrete but arguably very little benefit in doing so. The lime will only perform as well as whatever is behind it in terms of vapour permeability and flexibility. There's also an increased risk of cracking/failure due to differential movement between the two materials.
Hi, our apologies for leaving your question unanswered. Our lime backing coats are mixed at 3:1 by volume (sharp sand : lime putty) and the finishing plaster is 3:2 (fine sand : lime putty). The tools are summarised on our lime plastering page at www.mikewye.co.uk/guidesheets/lime-plastering/ Thanks!
How achievable is this for a competent diyer to learn over time......compared to the difficulty of the horrible gypsum stuff as I have done that in the past.....I get this is nothing like that but just mean in terms of difficulty in getting a nice finish
Hi Dave. Someone with a reasonable level of plastering ability will absolutely find lime much easier to work with than gypsum plaster (in our opinion). Lime is much more forgiving as a material and you will not find yourself fighting against the clock with rapid setting times. We can't account for levels of plastering ability but, if your skimming isn't at the level you want to achieve, you can always tackle the backing coats yourself and bring in a plaster to finish when it comes to the top coat skim.
Mike Wye oo this sounds brilliant I have skimmed a wall in the past in gypsum and managed to get at least a finish that was useable and looked fine.......I was under the impression that lime was much harder.....infact I’m in the middle of looking to make a step into retraining and have always said I would love to learn how to lime plaster as I feel their isn’t many that offer it
Fun video. They have modern products that not only will bond, but prevent discoloration and efflorescence. They can have mesh embedded in them to prevent cracking. There has been an evolution in materials. Traditional materials can still be applied as finish. In half the time , a slurry can be applied with a large brush as the first coat, then mesh applied with another coat the SAME DAY, then finishes and this will outlast these materials which will crack fairly quickly , especially on that cold joint. For a farm, this ok, but for a fine home, no way. I'm in the US and we sometimes have to give a 15 year guarantee for nice homes. Modern technology has improved the traditions.
tarun453 and they are all cracked and delaminating. I learned to plaster in Italy , the old way, slaking lime and mixing aggregate from scratch. It’s not self healing and it doesn’t last forever . Most of the old stuff has been patched ... a lot .
These videos really are great. As well as being clear and methodical, they don't miss anything out. As a result of following these I've now got a flat, lime-plastered wall that looks fab.
Hi Sam, thank you for the kind feedback, I'm glad you found the videos useful. We should have a few more coming out soon.
The bob ross of plasterman. Thanks for sharing your trade, this is perfect for colorado
That plaster going on is very satisfying, it's like cake icing.
What an awesome video! Who needs college when you can just read the Q&A below. Can’t wait to watch your other videos.
The sequence, the equipment descriptions, the timings and the small tips about the various pitfalls are excellent guys. Clearly you are craftsmen, but this has given me the confidence to have a go at all of the internal cob walls in my French country cottage.
I was going to batten and board out the walls as I was worried about getting a decent finish surface on the cob walls, but if I can follows your guidance I'm now more confident I can do it proud. Thanks for sharing
Thanks for the comment. If you give the office a call we can help you out if you have any more questions. Cheers
This really is a fascinating video with great commentary... It is like a sport with out the competition! Just love watching it!!
This is really good, professional workmanship of the wall and also the narrative. Thanks.
Thanks for the positive comment.
What a physical/technical artform!
Thanks for this Mr Wye. I have used your stuff on many occasions because your materials are always good and very usable.
Instead of using metastar I prefer using a brick dust. Harling is good and effective but if possible I prefer to use a mortar sprayer with a full sized compressor to do a thin 1st coat which I then blat it on at about 90 -100 lbs per square inch. I also use a wider tined scratcher but have cut away every other tine because they were too tight together, I also like to slurry area's before I scratch because it helps to bind the two surfaces together.
Many architects and builders cover their cob surfaces with metal mesh fixed with screws & plugs, resins or cone headed twisted nails but this isn't necessary if you do a 1st coat with a harl or a spray that should be sufficient, it's all about the key.
Many thanks, boys, for a detailed and explicit demonstration. I'm now about to try rendering a wall.....Great video!
We wish you the best of luck
@@MikeWyeLtd Thanks a lot, Mike!
I really want to learn this I have been in the building trade for a wile but something always pulls me towards lime and old ways buts the good ways .. I am going to learn this :) Just got to keep watching and get the process in my mind .. thank you to the guys teaching us what a pair of pros :)
Hi Mitchum, thank you for the kind words
Thanks for this video. It's been very helpful.
Dzięki, świetna lekcja.
Thanks much appreciate the video and your responses. Breathability and the way lime kill off bacteria fungi and viruses makes it a superb material. Looking at this as thinking of building hempcrete which has a friable surface so needs a lime breathable finish. Has long loved the victorian homes I lived in with set plaster walls and lime plaster wedding cake ceilings within handmade clay brick and lime mortar walls.
janet lesley Janet Im wondering if using Hemp in traditional plaster would be beneficial inbthe project i am currently inder going.Some origional Lathe work walls that need attention and some fine Oak timber beams in a Georgian period 1790 Out house
awesome video !!! very good information
Amit Patkar Thank you Amit
That is a beautiful wall.
This is by far the best video on this subject I have found, you are true craftsmen and thanks for sharing. I am trying to fix up some damaged areas on my heritage listed Georgian/Victorian building in Tasmania Australia. I would really appreciate some assistance in actually making the 'lime putty' or something similar using locally sources material. I can get the sand and hydrated lime from the hardware shop. Can I email you guys for some assistance? I can also send some pictures to show you what I am doing. Cheers.
Hi Graeme, Thank you for your kind comments. We will aid you as much as we can. Our email is sales@mikewye.co.uk
Great video. It would be great to get a little more detail on how much to let each coat firm up before going on to the next, or before floating, and how much pressure is being applied for each coat. I know that in a video it would be hard to get a clear picture of the firmness of each coat at each stage, but that's one thing I can't pick up without being there "in person".
Speaking of which! Have you ever considered offering a multiple-day course on lime plastering, spanning enough time to see how the stages tie together? Definitely worth building my next holiday around it!
So so good. So much learning
This is mesmerising
Excellent video, very informative thankyou 👍😀
Hi Peter, thank you for the kind feedback.
Very helpful! Thanks chap! Cheers... :)
***** Aye. Cheers mate. ;)
Nice video. It did take me 3 minutes to figure out that the guys were saying "hurl". No fault of theirs, I'm American.
It's actually 'Harl' but we won't quibble, thanks for the kind words
doirealyneed1 said
Thank you 🙏
Great video, some top skills on show!
I'm working on my 1890 (ish) terraced house and looking to redecorate one of the bedrooms. Removing decades of wallpaper has left a very rough, pitted surface unsuitable for painting. Is it a good idea to simply do a top coat using a lime plaster to provide a surface that could be painted, rather than taking the existing plaster back and doing more coats?
Stew Murray Thanks Stew! This video shows the full build up for internal lime plaster work but there are methods of renovating existing plasters to 'make good' without hacking off all of the old plaster.
Provided the existing plaster is sound and really just needs an additional skim, it can be primed with a low acrylic primer (we use Bayosan DG27 www.mikewye.co.uk/product/dg27/) before skimming with something like a 3:2 lime putty plaster www.mikewye.co.uk/product/lime-plaster/.
Whilst a thin, painted coat of the low acrylic content may sacrifice a little of the vapour permeability, it enables lime skimming onto a range of surfaces without the need to apply the full build-up of coats as shown in our video.
I hope this helps. Ryan
Just found your channel 👍 Excellent video 😎 I've been Plastering for 25+ year's. And have recently started working for myself. And have started coming across having to use breathable materials. Lime. But haven't done a great deal of lime. And when I have done. I've never mixed it up. I'm the one who puts it on the wall 😉 so would be very grateful if I could ask you a few questions about rendering with hydrated and hydraulic lime.
Great video 👍😎😎
Hi Neville. Thank you for your kind feedback - much appreciated. We're more than happy to help with any questions you have but you may find it easier to do so through our online chat via our website www.mikewye.co.uk, or by email sales@mikewye.co.uk, or on the phone 01409 281644.
We're here Monday to Friday 08:00-16:30 (GMT).
@@MikeWyeLtd Thanks Mike. Excellent. I'll contact you as soon as I get 5 minutes on chat on your website. Thanks again 😎👍
Neville Hayfield do post the questions and answers here so that everyone can learn something new.
Really good instructional vid. One question. Is it okay to stop after wood floating? (as I like the rough texture) Then lime wash over that?
Absolutely. The finish is 100% your call. Many people prefer a more textured, rustic finish rather than a smooth plaster skim.
Great video, thank you. I grew up around buildings with lime construction. There is something so serene about the texture and feel of these buildings. I would love to incorporate lime plastering on the walls of the farm house I am going to build in Dominican Republic. Is there a video on lime mortar preparation? I have videos from other folks, but would love to see how the mortar/putty was mixed (that was used in this video).
Cave Man Thank you for your comment. In our early days we used to mix lime mortars and plasters on a smaller scale but sadly we don't have any videos of the process. These days we mix in larger agricultural mixers so not sure how relevant a video of that would be. We're happy to answer any questions you might have though.
+MikeWyeAssociates It would be marvelous to see a mixture video!
+aghostdream what do you have in mind?
+MikeWyeAssociates Perhaps just a short video on mixing by hand?
+Cave Man When I was a kid plaster walls were built up on wooden lathe strips and it was very strong though prone to micro cracks. Frequently hair was mixed in [I heard horse hair but no matter] to reinforced the plaster. Now I presently live in the DR and am thinking of using coir fibre from coconut husks to strengthen and reduce cracks.
This video is quite wonderful. I'm located in far west Texas close to New Mexico and looking to use lime plaster on exterior and interior adobe construction.
Hi Alexander, thank you for the kind comment. Best of luck with your project!
I can tell Rick has done this before.
A great video, very informative. What type of paint to you recommend for lime plaster on internal walls? Does regular water based emulsion still provide adequate breathability?
+Voodoo Melon Apologies for the slow response. The key thing to look for when choosing a paint is that they do not include acrylics. Modern water-based paint often still contain acrylic which forms a restrictive layer over the plaster. Thankfully, there are many paints on the market which allow excellent vapour-permeability (breathability) in a good range of colours. These include: clay paint, lime paint, natural emulsion, silicate paint, and the more traditional distemper, casein paint and limewash. Take a look at our website for details and colour charts on all our breathable paint finishes www.mikewye.co.uk
Fantastic, thanks!
Excellent 👍👍
Excellent video. Thank you for this, it's been really helpful for me. Is harling the same as scudding, another term I've heard used?
Hi James, yes it is the same. Thank you for your kind comment.
Thanks, Mike. I'm really looking forward to having a go at this. I'm tempted to practice on the inside of the garage first. I'm guessing that concrete blocks from the 1980s aren't exactly breathable, but at least I won't make a mess of the walls inside the house trying it for the first time there!
Good luck, we are always available on the phone for help and advice, should you need it.
I'm doing one today for my first time hopefully all goes well
Good Luck
How did it work out thinking of doing this thank you
Good video.
Once dried .if there are any knocks and slight damage how do you fill?
Clean the area and damp down, apply a small amount of material and float/sponge over as it dries back. You may find a finer sand mix easier to blend but it can be done with the standard mortar
So glad our materials in Australia are more refined and don't require so many coats. Just one coat at 10mm thick and it's done.
Not the same material. Gypsum is fine but nothing beats lime on old buildings.
I like the use of the venetian trowel. What size trowel is it, 11"?
metacaolin question: do you add 7:1 ratio to the lime putty or 7:1 ratio to the entire mortar mix, I remember reading somewhere that metacaolin is highly reactive and you only need to add 2 to 5%, adding too much may cause shrinkage issues as well. on the other end of the spectrum brick dust is of low pozzolanic reaction and you can add 1/3 of the aggregate (25% of the mix) up to 100% of the aggregate can be replaced with brick dust, depending on what final properties you are trying to achieve. rising damp issues, etc...
Fabio Bardini, we add the metakaolin to the mortar at 1:7.
The addition of pozzolan is an interesting and broad subject which has recently been revisited by the Building Limes Forum in the U.K. as the theme for this year’s annual conference.
We try to keep our finger on the pulse with all new developments and research, however we’ve been using a gauge of metakoalin with traditional mortars in these sorts of volumes for 25 years without any resulting shrinkage.
Many other pozzolanic additives can be used but may not be easily accessible, can be inconsistent in their reaction, or can have an unwanted effect on the mortar colour.
We’re happy to discuss this further if you’d like to call our office, or email us at sales@mikewye.co.uk
Great videos! I was wondering if you had some more information on that harling coat though. I'm currently struggling with some old, extremely thirsty brick walls. I managed to get the first coat on nice and flat and soaking the wall gave me just enough time to do it. However... I applied the my first coat months ago and now it's bone dry. I've tried soaking the walls again but the finish coat, I supposed because it's much thinner, just keeps drying out too fast... by the time that I'm at the bottom, the top is pretty much dry to point where I can't work it anymore. Fighting it with a wet sponge helps a bit but so far I've only done small walls to test. This method is not going to work on my bigger walls... I'm wondering, could the harling coat help before applying the top coat as well? How much pozzolan might I add? Thank you for your help!
Sorry for the delay in replying.
Are you doing a full internal lime plaster build-up with a harl coat, scratch coat, float coat, and skim, or is this an external render application? If so, what stage are you at now?
If the coats are applied "green-on-green" then the previous coat shouldn't have dried out so much that it's very thirsty like you are experiencing. As the last coat you applied was done many months ago then you may benefit from another harl coat (assuming you are at the float coat stage).
I'll presume that this is an external application given that you've asked about the addition of a pozzolan. We should safely be clear of the risk of frost now so early spring is a great time for render applications to give plenty of time for carbonation and strength gain before the winter. With that in mind, and given that you have very thirsty walls, I wouldn't go any more than 1:8 pozzolan to lime render by volume. There may even be a case to reduce this to 1:10 provided that the area isn't particularly exposed or vulnerable.
I hope this helps but feel free to give us a call on 01409 281644 if you would like to discuss.
Best of luck with the project! Ryan @ Mike Wye
Could I use a ultra fine hair brush at the last sponging stage or after? Plus would memory foam have a similate effect to a more dense sponge.Im preparing to Lime plaster the interior walls of a Georgian period Out house,many thanks
Hi, It's worth having a try with the memory foam but it may be too dense. Are you using the brush for an effect?
Nice informative video , in many parts of India too, people who build traditional with help of lime, n plastering too is done with mixture of sand ,clay, n lime,
One more thing if u want to build one of the wall of stones of ur house then try to find out how indians use to build mortar with help of jaggery,black gram lentils, Fenugreek seed, n some other sort of bitter tastes liquids to keep away termites
Hi love the videos thanks, i have a question can you do sections at a time, Example I have a Large external wall I need lime rendered, in planning to do it myself, could I do the wall in 3 stages with no bells , just flat and do section to finish coat different days?
Hi Mike, you could do the harl and scratch coats in stages but you would need to try and complete the float coat in one (it's very hard to disguise joins in the float). If there are down pipes, that would be a good place to stop and start.
@@MikeWyeLtd OK, than you for the reply awesome
Is there a way to fix little imperfect rough patches before lime paint? Thought maybe a skim coat of putty or NHL paste ?
Assuming that they are slight imperfections then the paint or limewash itself can help to improve and disguise blemishes. If the patches are beyond fixing with a paint then it may be possible to feather in a fine lime putty filler or put a very thin skim over the entire area if the plaster is still relatively green.
Great vid! Do you have any info on mixing (ratios, materials etc...) :)
lozington95 Thanks for your kind feedback. We’ve just revamped our Practical Guide which can be downloaded as a pdf here www.mikewye.co.uk/product/brochure-practical-guide/
or you can request a printed copy 👍🏼
Question: would the same techniques apply to plastering an internal hempcrete wall?
Are you using putty or NHL in this 3 to 1 mix? Thank you. Just getting into this work myself.
Sorry just heard the mention of putty.
It's a lime putty mixed at a 3:1 ratio by volume with a pozzolan added (Argical M1000) at a 7:1 ratio by volume
The soil around me is acidic. Seeping water is bound to have a low PH. I bet lime-based mortar will get eaten up pretty quickly and efflorescence will develop at the joints on the inside wall. Any thoughts on how to prevent it? Also, would adding the "potslan" (spelling?) help keep it water proof?
Although a wet lime mortar is highly alkaline, once carbonated it becomes pH neutral. As long as the walls don't become saturated and if both internal and external sides are lime the wall with breathe and should not cause any problems inside. The pozzolan increases compressive strength and helps to protect from frost and generally makes the mortar more durable.
Is it hydrated lime you use? This may seem like a silly question but I have no idea
Hi, no we manufacture lime putty here so we use that as it provides a richer mix but hydrated lime is a dried version of this. We use a ratio of three parts sand to one part lime putty by volume.
In Korea, In my opinion, Not quick lime But Hydrated lime. in these kinds of cases, traditionally use Hydrated lime(quick lime + water = Hydrated lime). lime putty, lime mortar etc...
The work of Master Craftsmen. Impressive knowledge and patience. Do you travel as far as Totnes?
Thank you Carey. Totnes is a little further south than we usually cover but not completely out of the question. If you have a project you’d like quoting for them we can also put you in touch with suitably experienced and knowledgeable trades people in your area.
Ah-ha. I wasn't sure if you were nearby because I detected a Cornish/Devon accent. Considering I just have one internal wall (approximately 2.5 m x 4 m) - and one external length of wall which is only about 4 m², it probably is not worth your while coming all this way down if you are "Up-country".
It would be useful if you could recommend somebody in my area.
Congratulations once again on your incredible work - hopefully this Will prove a good platform for you to get more work in your area.
Carey Marks you’re absolutely right about the accent. We are in Devon but in the north so it’s not always cost effective for us to travel for such a job. If you drop us an email to sales@mikewye.co.uk then we’ll give you a couple of contacts who can help.
Thanks again for the kind feedback. Regards, Ryan
I have an old house, with lime plaster on the interior. The lime is pretty old and degraded in some little areas, but I know that lime helps the old walls breathe and i don't want to change it with cement based plaster. My question is, is it good, and will this type of plaster sustain a clinker brick finish (1-2 cm thin bricks applied on the wall via a special based adhesive) that I wish to apply to it? Or do you recommend an cement based plaster?
Hi, you would need to check the adhesive for breathability as it would be covering the lime. Also any cement based adhesive will be a lot stronger than the lime and may cause delamination (especially on old lime)
@@MikeWyeLtd Thank you!
So the harling mix is 3.5:1 but it's really runny. I'm guessing that's because you added so much water. Doesn't that make the mix pretty weak? How will it cure properly and be strong? Or is it just supposed to be there to prevent sucking as much with the scratch coat?
Thank you so much for these videos. For an amateur like me they are super informative and helpful. I do though have a few questions I wonder if you could help me with? I’m in Portugal and have a early 1900’s stone walled house and really want to use traditional methods to do her up.. my builders are of course pushing cement…. When I suggested lime, they said Yeh sure, but we HAVE to add 1cement to 1lime to give it strength otherwise it’s like powder and will just mark with any small bang… Is this true?
My other question is, do I have to add hair or any other type of fibre? Or can I just do the lime sand mix?
It’s hot here and I’m wondering how to help it dry properly(not too fast)? I see you splash water on some of the layers but how do I control the final plaster one?
What’s the difference between lime mortar and lime plaster? And what sand do you use? Is there like a grade to go by? They are using quite tough sand here which I don’t like but they say after this one there’s on,y one that’s ever do slightly more fine, which I don’t think I could ever achieve these smooth finishes with?
Thank you so much! Hugely appreciated if you find the time x
Thank you for your kind comments. Our mixes are one part lime putty to three parts sand by volume. This is a traditional mix that air dries and carbonates. The lime that your builders are referring to would be hydrated lime (a dessicated lime putty) that is used as a plasticiser in cement mixes.
For a compromise you could use NHL (natural hydraulic lime) at the same 3:1 by volume ratio. This is very common in Europe and easily accessible. The NHL is a dry powder that will give a chemical set with water rather than air-drying. It's a bit of a compromise.
Water and protection from direct sun are the main ways to control drying.
Our mortars and plasters differ slightly in mix ratios but essentially it is the aggregate size that makes the difference.
@@MikeWyeLtd thank you so much for you quick get back, much appreciated. Hydraulic lime, that’s the one! They still want to add cement to that though which is annoying, 1 lime to 1 cement then sand.. as they say it will be super soft and any little bang will make a mark on the wall. As for the controlling of drying time, I’m slightly worried about this as they they will do it when it’s warmer and Portuguese sun is HOT whatever the tone of warmer months.. so I’m worrying it might dry out too quickly. Should I spray it every day or something to help it along? Thank you so much again x
@@leafside A 3:1 mix of NHL3.5 and sand shouldn't be too soft, the lime putty renders are softer than these and still take a fair bit of abuse. Yes regular damping down will be beneficial.
@@MikeWyeLtd thank you, will put that to them x
Just moved into a cob cottage that has been cement rendered outside & inside on the ground floor. Silicon injection damp proofing to prevent rising damp. Is it worth using lime mortar internally on the first floor.
kate herd, our apologies for missing your comment a few months a go.....not sure how that happened. There can be some real benefits in using lime plaster to help with moisture management and for the benefit of the property. However, we always encourage breathability to the outside first wherever possible. If you are considering improvements or need to replace renders or plasters due to dampness or damage then it may be wise to address the external cement render first, finished with a breathable paint.
Hi Mike such a good informative video. Quality work. What is the difference in technique/materials this to an external wall?
Hi David. Thank you for your positive feedback.
The application for an external render would be almost identical apart from a couple of details:
The lime plaster skim would be too weak and vulnerable for external use and therefore the top coat would be a finished unhaired coat rather than devil floating it as shown here.
We also recommend the use of a pozzolan additive for external works (particularly if you're in the UK given our climate!) to bring on an initial strength gain and protect from adverse weather and frost in the future. Regards, Ryan @ Mike Wye
Ryan, thanks so much for the prompt and informative feedback really appreciate your help. Are you still supplying materials at the moment incuding delivery?
Ah I just ready your notice on your website. Hope things get back to normal soon. Wishing you the best.
@@davidharness1507 Thank you. We hope you and your loved ones keep well through these challenging times.
Internal traditional chateau walls are usually about 4 metres high and say roughly 5 metres wide. How do you get them straight and can you do the whole wall in one coating or do you need to do the wall in segments?
Hi Jack. A 4 m x 5 m wall wouldn't present a problem for a competent plasterer as an entire area. You would not need to plaster in segments.
Are these plaster layers breathable? Is there a huge difference between these and external mixtures? Can these be painted with a natural paint? It's very rainy where I am as well.
+aghostdream Yes, lime render and plaster is breathable. An internal render is typically a 3 coat buildup, with 3/1 haired mortar as the scratch coat, 3/1 unhaired as the float coat, and then a skim of 3/2 plaster. Externally, it would be just the first 2 coats, and we would recommend a 3.5/1 mix, with pozzolan added for a more regulated set. For external use, we would recommend a silicate paint www.mikewye.co.uk/product/seciltek-silicate-paint-sp-01/
+MikeWyeAssociates thanks very much for your reply! I'm quite new to this.. When you say 3/1 is that the ratio of lime to another ingredient?
+aghostdream 3 parts sand to 1 part lime putty (by volume)
+MikeWyeAssociates thank you!
Does anyone have any ideas about whether they think it could work to lime plaster the walls on a tiny home? It is on wheels...
Hi Jemima, we have a customer with a static caravan that is moved fairly regularly. He has had some small cracks appear that he has patched in. If things are fixed well it may be ok but faults may appear when it is moved.
Hi, i'm getting ready to render my walls, can you tell me what type of sand are you using, is in rendering sand or building sand on all 3 coats. thanks
The backing coats use a sharp sand, typically 0-5mm with a good spread/blend of fine and coarse sized aggregate. Many merchants supply 50/50 sharp sands which can be a fairly safe bet if there’s any doubt.
For the top coat lime plaster skims we use a kiln dried fine sand (kiln drying removes the majority of lignite therefore minimising marks on the plaster). The size of sand can vary depending on the fineness of finish required. For example, Georgian and Victorian town houses typically had smoother finishes when compared to 16th century cob and thatch properties.
As a guide, somewhere around 0-0.25mm aggregate size will achieve a good result.
By plastering over my 140 year old brick chimney wouldn’t this destroy it because it won’t breath? Most of the work will be indoors behind walls
If you used a lime putty mortar/ plaster system the wall would still breathe. You would want to make sure that the paint is also breathable.
can this be used for outdoors? Would look fantastic on my retaining wall
Hi HalfKatzBoy, It can all be used outside apart from the last plaster skim coat. This wouldn't cope with the weather as the aggregate is too fine and the coat too thin.
Hi. The process is fairly similar for rendering externally but the skim coat is omitted. You can find our external render RUclips video here: ruclips.net/video/1sjVSMypSvY/видео.html
I have zero plaster experience but recently motivated in the subject. Often heard about “preventing shrinking” here in your video too. what we want to preventing of? Why it is a necessary :) hope you don’t mind to explain :) thanks
Shrinkage can occur in mortars and plasters for a number of reasons but ultimately results in cracking which would need to be repaired afterwards resulting in weak areas and possible scarring.
Causes of shrinkage are:
*High suction from the substrate/insufficient control of suction in the substrate by dampening with water/use of primer etc.
*An overly wet mix (the excess water evaporates away during curing causing the mix to crack)
*Use of incorrect mixes/aggregates. For example, if you try to apply a fine internal plaster which is designed to be skimmed at 3-4 mm thick at 6-8 mm thick then the plaster is likely to shrink back due to the aggregate not being sufficiently large to hold its form.
*Fast drying. If plasters, renders and mortars are subject to direct sunlight/heat/strong winds/high internal temperatures then they moisture contained within them will evaporate rapidly causing shrinkage. Mixes should be left to cure naturally and not force dried. If the external temperatures are high and/or there is prolonged direct sunlight on the area then the surface should be protected by using damp hessian/sheets/old curtains etc. Protecting the surface of external renders is advisable irrespective of time of year.
I hope this helps.
You’ve done a glasscrete video for internal floor. Can you do one for creating an external flagstone surface in a yard? Limecrete or Glasscrete?
Hi Peter. Thanks for the suggestion. We're gradually adding videos to our channel so will consider adding something along these lines in the future. If you do have any specific questions in the meantime please do email us at sales@mikewye.co.uk or call the technical sales team on 01409 281644
What do you mix with the lime on the final, you mentioned two to one mix
Hi Fred, we do two finishing plasters, Heritage (3:2) 3 x parts kiln dried sand to 1 x lime putty. Regency (1:1) Marble dust : Lime Putty
Robert Plant master mortar man.
Don't forget to cover the BMW, cat... Lol
Dallas Mcmanus 😂
Hello! What is the mixing ratio of ingredients in this lime mortar? Also, what is a good mix ratio of lime and sand for an interior plastering?
Hi, the mix ratio is 3 parts sand (sharp 4mm - Fines) and 1 part lime putty. For plaster we tend to use a kiln dried sand at a 3 part sand to 2 parts lime putty
@@MikeWyeLtd Thank you!
@@MikeWyeLtd The sand graded up to 4mm is for the base and float coat only, correct? But for the two skim coats, since they are only 2-3mm thick I think you guys mentioned, then the sand would have to have a maximum particle size of 1mm, no? And for the skim coats do you still use sharp sand because I thought I read somewhere that one might want fine smooth sand instead of sharp to have a smoother final surface, especially for interiors, or? Wonderful video, thank you!
@@quayd Hi Yes, we use a kiln dried sand and/ or marble dust for our plasters
Why was the wooden float use? Also could you not have used the devile float when render was workable?
I want to do ready to use dry mix lime plaster. Let me know which lime to use? sand:lime proportion? what to do to accelerate setting time?
Hi Sameer, you can use an NHL (Natural Hydraulic Lime) either NHL2 or 3.5 mixed with sand, this has a chemical set with water. You wouldn't really want to accelerate the setting time but with this sort of lime it should be 'green hard' after 24-48 hours. A 3:1 mix ratio by volume is commonly used.
+Mike Wye Thank you. Also I had heard that sulphur powder is also used. Is it correct?
@@SD-bg4pm Many powder pozzolans, such as fly ash, brick dust and metakolin, have an effect on the mortar strength when added. We generally add them to traditional lime putty mixes to improve strength and offer better protection from frost. It's not necessary to add them to a hydraulic lime mix as the strength can be somewhat determined by the correct grade selection (NHL2, 3.5 or 5)
hey mate, I have a bag of quicklime and i also have a bag of hydrated lime i want to sample for wall rendering...what ratio do i mix the quicklime to water (slake) to make putty? and do i soak hydrated lime also into a putty, & if so what ratio to water is it? Super hard to find any information about the ratio to make putty...is hydrated lime able to be used for wall rendering?
Hi Johny. You really do have to be aware of the hazardous nature of quicklime if you're considering slaking it yourself. Our guys wear full face masks, body suits and gloves in a controlled environment when slaking.
If you're comfortable you can manage the risks safely then we can give you a guide for the quicklime to water ratio by emailing sale@mikewye.co.uk
Hydrated lime can also be rehydrated to make an inferior lime putty but we don't really recommend it be used as a binder for rendering. It's typically reserved for use as a plasticiser in a cement mix (6:1:1 aggregate:cement:lime as an example).
@@MikeWyeLtd hey mate thanks for the prompt reply. Yeah unfortunately i have to undergo the process of slaking myself. Im on an island in Indonesia and there is not such thing here of a bucket of putty let a lone even quicklime or hydrated lime bags...what im wanting to do (render my villa walls with a lime mortar) is revolutionary to these parts, mould is shocking here with the humidity. I found a mining company in Java that sent me a 20kg sample of both products (quicklime and hydrated). I have slaked a small quantality of the quicklime to check out the reaction, and do sample renders...im prepared mate, but unsure exactly the ratios. I will email you.
Sorry if I missed it, but how thick does the scratch coat want to be?
Hi Simon. We typically assume 12-15 mm material consumption for the scratch coat. Of course you may need to consider extra material for dubbing out and, in some instances, an additional scratch coat if the walls are particularly uneven.
Regards, Ryan @ Mike Wye
@@MikeWyeLtd Thanks. I see on your website that two scratch coats are specified, is this optional? I.e. if you are happy for the walls to be uneven and retain their character, can one coat be used? We are specifying both internal plastering and external roughcast render.
Also - with the roughcast, do you add the aggregate to the harling coat, or do you add the harling coat then fling the aggregate at it? Thanks in advance. S
@@simonblunden6751 Exactly. If you have particularly uneven walls then you will likely need an additional dubbing out coat to bring the walls level before application of the float coat. If you would like to retain some character, or if the walls are relatively flat (such as brickwork or block) then an additional coat will not be required. Regards, Ryan @ Mike Wye
@@simonblunden6751 The roughcast/harl coat as shown in the video is a thinned down Unhaired Lime Mortar mix. We generally use something called Reabilita Cal CS (otherwise know as Consolidation Mortar) for harl coats these days as we can supply exactly the correct amount without having to work out how much of the Unhaired Lime Mortar to separate plus it is generally ready to receive a scratch coat in 24-48 hours.
Always wear glasses while harling! I learned that yesterday, the hard and painful way. :-/
Yes it is very unpleasant!
@@MikeWyeLtd Thanks for posting this. So few videos about plastering over cob. I've got a question, if you have a quick second. I'm getting more cracking in my hair and scratch coats than I'd like. I think I'm having trouble getting enough aggregate in my mix. I aim for 3:1 but end up at best with 2.5:1 and sometimes closer to 2:1. I just can't work it when it is 3:1 -- it is very stiff and not at all workable. I don't want to add water, do I? My putty is about the consistency of toothpaste, so I think that's right. I'm not sure what's going on. In both cases, I've added 1 part hair (in my case it is 2"/5 cm lengths of shredded linen discard fibres). Any ideas? Thanks again for the resource and I'll understand if you don't have time to respond.
@@LowTechInstitute Thank you for the kind comments. It may be that you need to let the mix turn longer to increase the plasticity, it may also be that the linen is absorbing some of the water content. If this is the case you may want to introduce a little water but you're right not too much. I hope this helps.
@@MikeWyeLtd Thank you for taking the time to reply!
@@LowTechInstitute No problem, good luck
Wow do you do the lime mortar?
GuitarraLisboa1977 Yes we do. We manufacture and supply traditional lime mortars and plasters as seen on this video
okay .. thank you.. but its impossible to buy frome you guys.. shipment frome Australia to Portugal (no sence)... We also have Lime... and it would had to be done here.. thank you anyway
GuitarraLisboa1977 GuitarraLisboa1977 We’re a little closer than that in the U.K.! We also supply Portuguese lime (Secil Argamassas) but I’m sure it’s much easier for you to buy in Portugal. Kind regards.
yes, thank you
How to get Greek plaster look can you please tell us the material and technique to get Santorini house look..
How thick would the lime plaster layer be in total?
Hi Hazel, plaster coats are typically around 3 mm
@@MikeWyeLtd sorry i mean for the whole thing, from the wall to finish, including the mortar etc.
@@hazellewis6995 Hi Hazel, onto a solid wall typically, 12-15 mm haired scratch coat, 8-10 mm unhaired float coat and then a 2-3 mm skim
Do you know the thermal calcs on this
Lime putty and sand has an approximate k value of 0.8
Watched this video with the intention of learning how to plaster my old farmhouse walls.......but came away realising it really is a dark art, and I'd be better off getting a skilled plasterer in !!
Nah it's super easy. Lime plaster is easy to work with. Give it a go mate
You could practice on an area in the barn...you may surprise yourself
its a lost art, you simply wont find anyone willing to put the effort and time(few days). You better off doing it yourself
Is it possible to get the recipe of the different lime plasters? Thank you!
There are no real trade secrets when it comes to the mix ratios used for mortars and plasters. Mix quality can be affected by the type of lime, its production process and the careful selection of sands.
The mix you should be using is influenced by the type of work, time of year and exposure (where work is external for the latter two points).
If you're ever in doubt, speak to your lime supplier (we assume Mike Wye, of course!) and they will be able to advise you.
Have you applied this on Concrete wall?
It's absolutely possible to apply lime plaster or render to concrete block in the same way. This could be done for aesthetics, to match surroundings or from an environmental viewpoint.
great video to me it seems you could have floated it s bit sooner so your not having to use so kuch muscle
Great video mate just need more on the speaker can't hear you good or maybe it just me mate , but well done
Thank you for the kind comment, Rick has been known to mumble :)
i love this video... still
I feel like I'm listening to announcing at a golfing tournament.
That's what I was thinking 😂😂😂😂
Can I use lime mortar over concrete!!
Hi Ramona. Sorry for the delayed reply over the festive period. It's possible to apply lime over concrete but arguably very little benefit in doing so. The lime will only perform as well as whatever is behind it in terms of vapour permeability and flexibility. There's also an increased risk of cracking/failure due to differential movement between the two materials.
Can we get all the recipes for the different mixes? And the names of the all tools you use.
Hi, our apologies for leaving your question unanswered. Our lime backing coats are mixed at 3:1 by volume (sharp sand : lime putty) and the finishing plaster is 3:2 (fine sand : lime putty). The tools are summarised on our lime plastering page at www.mikewye.co.uk/guidesheets/lime-plastering/
Thanks!
Where can I buy this product line putty
www.mikewye.co.uk/
Looks like "Harl"="Hurl" ;)
Hi Peter, yes it has many names, regional variations I guess. We have also had 'scud' and 'scat' but I wouldn't google the latter :)
Hi mate, that looks lovely. Your not free today are you?
😂
Which material is used?
The materials in this video are made from traditional lime putty and sand.
@@MikeWyeLtd how to do make home with lime ?tell me and also thanks for ur reply
This is indian vedic method of plaster
How achievable is this for a competent diyer to learn over time......compared to the difficulty of the horrible gypsum stuff as I have done that in the past.....I get this is nothing like that but just mean in terms of difficulty in getting a nice finish
Hi Dave. Someone with a reasonable level of plastering ability will absolutely find lime much easier to work with than gypsum plaster (in our opinion). Lime is much more forgiving as a material and you will not find yourself fighting against the clock with rapid setting times. We can't account for levels of plastering ability but, if your skimming isn't at the level you want to achieve, you can always tackle the backing coats yourself and bring in a plaster to finish when it comes to the top coat skim.
Mike Wye oo this sounds brilliant I have skimmed a wall in the past in gypsum and managed to get at least a finish that was useable and looked fine.......I was under the impression that lime was much harder.....infact I’m in the middle of looking to make a step into retraining and have always said I would love to learn how to lime plaster as I feel their isn’t many that offer it
Mike Wye maybe I’m just kidding myself haha
"3.5 to 1 or 3 to 1 lime mortar mix". Do you mean 3 parts sand and 1 part lime?
Hi Luculencia, yes 3 parts sand to 1 part lime by volume
@@MikeWyeLtd Thanks! :)
If you're having a a go at the the neighbor's BMW perhaps you should substitute in boxing gloves.
Fun video. They have modern products that not only will bond, but prevent discoloration and efflorescence. They can have mesh embedded in them to prevent cracking. There has been an evolution in materials. Traditional materials can still be applied as finish. In half the time , a slurry can be applied with a large brush as the first coat, then mesh applied with another coat the SAME DAY, then finishes and this will outlast these materials which will crack fairly quickly , especially on that cold joint. For a farm, this ok, but for a fine home, no way. I'm in the US and we sometimes have to give a 15 year guarantee for nice homes. Modern technology has improved the traditions.
modern products= quick and cheap to apply, followed by = quick to fail and expensive to replace.
tarun453 and they are all cracked and delaminating. I learned to plaster in Italy , the old way, slaking lime and mixing aggregate from scratch. It’s not self healing and it doesn’t last forever . Most of the old stuff has been patched ... a lot .
Bb
I forgot to cover my cat before doing this.😃
have you heard of render because plaster is the stuff they put on plasterboard. but other tan that great video mate from australia.
This video shows the full build-up of coats, harl, scratch, float and plaster. Plaster is not only for plasterboard
@@MikeWyeLtd i never said its only for plasterboard did i? no i did not
the video is 2 seconds faster then the audio
Get a life
Lollll
I like to shave the hairs with an electric razor if they're poking out too far.
If that's what you like to do, then by all means carry on...
Use Indian ancient technology lime plaster..... Instead of uropien cement......
Hi, there is no cement in the lime mortars that we produce, just sand and lime putty