The Best Way To Seal Earthenware Pottery, 4 Methods Compared
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- Опубликовано: 14 окт 2024
- Because earthenware pottery is by nature porous, it is important to seal eating, drinking and cooking vessels. Here I try 4 different sealing methods on identical bowls and compare the results to show which method of sealing pottery is superior. Lard, milk, starch and a commercial cutting board sealant go head-to-head.
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I bought an unglazed earthenware pot about a month ago and filled it with water, and when I came back the following day, water had seeped out of the bottom of the pot and collected in the larger pan holding the pot. I then decided to seal the pot. I soaked the pot entirely in water for 24 hours, and the moment I put it in water I could hear the pot's porous walls absorbing the water. The next day I came, took up the pot and gently wiped the pot with a cloth, and when the pot was still damp, I spread coconut oil on the inside and outside of the pot. Afterwards, I set the pot in the hot sun so that the oil will fully absorb within the pores of the pot. After the oil had been fully absorbed, I then placed rice water (water wherein rice was left to soak for 1 day) into the pot, along with a little rice flour, and I brought the rice water to a boil. Afterwards, I poured out the hot rice water and allowed the pot to cool off. After cleaning the pot from the residual rice product, I refilled the pot with tap water and placed the pot in a larger pan to see if the pot will continue to seep. After 24 hours, I checked the pot and the larger pan, and, lo and behold, there was no seepage! The earthenware pot was completely sealed and could now be used for cooking.
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Coconut oil and rice flour huh. I seriously doubt it is 100% sealed as you imply but I don't doubt it is a reasonably good seal.
@@AncientPottery I have yet to cook in the pot after sealing it, except when simply boiling the rice water. I really do not know what is going to happen after repeated use. What I do know is that after refilling the pot with water for 24 hours, when I came to check its outer surface, it was bone dry. I do know also that when I enquired about the method of sealing clay pots in Yemen, I was told that they spread oil over the pot. They made use of sesame oil in Yemen. These are time-proven methods.
@@AncientPottery Well, I guess you haven't seen the video-link that I sent to you, showing a woman from India explaining how they, in their country, prepare clay pots for cooking. I simply followed her method.
doesn't make sense, you cooked rice water in this clay pot. what , in an oven, certainly not over a flame??
Milk glazing is a common thing in Europe and here in Ukraine. But what we do is bake it longer for milk to caramelize (and turn brown, which can be decorative). It holds liquids better that way. Also it can make pottery more shiny
Slava Ukraine
I also wonder why people don't caramelize the oil because it forms a hard coating which seals the pores.
Hi, what temperature do you bake it at? @Kvassvideostash2162
@NashBashy max setting of your stove works well. ~200°C for hour or two, depending on colour that you want to achieve
My immediate thought when you mentioned sealing with oil is to try the Charles Law technique. You heat your oven to 350f. While the oven heats, cover your pot in a food grade oil like linseed or olive oil and let soak a bit. When the oven is heated, place the pottery in the oven for 3 minutes, then remove and allow to return to room temp with the oil still on the surface. The idea is that when the item is heated, the air is pushed out of the pores in the surface. Then when the surface cools, the air is pulled back in, but since there's a layer of oil on the surface, it gets sucked into the pores. I have done this with a wood cutting board and utensils, but never tried with pottery. The oil will remain in the wood unless it is heated beyond 350 again and has not become rancid in 3 months since applying it to my cutting board. Might be a fun experiment.
Yes, polymerizing oil has to be the best technique. When an oil polymerizes it essentially turns into a type of plastic. What this means is you gain an extreme amount of durability and longevity. Most oils require high heat to polymerize, like you explain here, but some oils polymerize at room temperature. These are known as drying oils. Linseed and walnut are both drying oils and would be what I'd recommend to start with as they are known to be food safe after curing.
Interesting, I will need to try that out. Thanks
Your explanation for how it works isn't quite right, but you've got the type of oil correct. As another comment stated, Linseed oil is a polymerizing oil. You should just treat it like a cast iron, minus the applying oil hot (many people do this to cast iron). Use any polymerizing oil, or even a food oil like vegetable oil or canola oil, so long as it's heated hot enough to polymerize it, it will function as a barrier. If air can't break through it to damage cast iron, I don't imagine water can get through it either.
@@D-Vinko there are articles out there on which is the best food oil to use on cast iron, and carbon steel too. You’re wanting a high smoking point, if memory serves , to achieve better polymerisation. And as you say, this is the same process.
I think what most were saying when they said "weight the water" was to suggest you weight out two cups of water (16 oz) with the scale. Then after testing unglazed and glazed pots to weight the water that is left in the pot. That way if you know you started with 16 oz of water and were only able to reclaim 11.5 oz of water you know EXACTLY how much water was lost. Whether the water was absorbed or leaked out or evaporated the pot was only able to "keep" the amount of water you can measure after pouring it out. I know your interest isn't the science but science methods can provide less intuitive data that is easier to interpret. Just my $.02
Thanks for the video.
This exactly. Measuring arbitrary volumes accurately and precisely, even with decent lab equipment, is not easy (or maybe more carefully, it's easy to introduce unintended errors/imprecision). With kitchen volumetric tools, you can get reasonably repeatable measurements of some values (ex: 1/4, 1/3, 1/2 cup) but volumes between increments are tough to gauge well. (And yes, that includes metric values, for the rest of the world - a tool doesn't suddenly become more precise and accurate simply because of the scale you're using.)
@@jasonpatterson8091 _"And yes, that includes metric values, for the rest of the world - a tool doesn't suddenly become more precise and accurate simply because of the scale you're using."_
Yes, it does.
- With metrics you know that 1.000 milliliter of water equals 1.000 gram. - Weigh the water in grams! It is that easy.
- How many milliliters or grams is 1/3 cup, exactly? - And how do you measure it, exactly?
Since all your sealers were food products (or food safe in the case of the commercial stuff), I'd have been awful tempted to taste the water out of each one after the measuring step, just to see if that particular sealer made the water taste funny.
When it comes down to it, I can't help thinking a sealer that didn't make things taste weird would be preferable to one that seals a little more effectively.
Love your work, Andy! Keep at it!
Good point and something to keep in mind for future videos. thanks
And here, ladies and gentlemen, we have the inventor of beer reincarnated.
Trying to seal pottery, using starch soup in the open (so yeast can get in) and heating things up. Some-one tasting the water after the process and find the taste a bit bitter but somehow okay enough to take another swig and another.....
Have you tested "blackening" the pot? You pull it out of the fire while it's still hot and put it in a pot or basket (lined with clay) that is full of a sappy or resin leaves. I prefer pecan, hickory, sweet gum and lastly, oak. The first three will give a glossy finish, oak or grass will give a duller finish. Grass and pine will also cause everything you cook in that pot to taste like grass or pine.
Blackening was pretty common in the southeast, especially during the Mississippian era.
Called "smudging" it is also common in the ancient Southwest especially among the Mogollon groups. I just smudged a couple of pots on Monday. I would love to see some science to show how well this works because it seems to me that it is not very effective at sealing.
I'd be careful using pecan leaves because they are very high in acid
Go to some old neighborhoods where the homes were built in the 20s and 30s that had pecan trees and look at the driveway. I get a lot of calls to tear them out pecan trees are the worst on concrete
If you have a pecan trees make sure you keep the leaves raked up or blown away
It only takes a couple of years of leaving your leaves on it to ruin it
Andy, this is definitely science. Your hypothesis is that treated earthenware pottery can hold water longer than untreated; and that some treatments might work better than others.
Only problem with the first hypothesis is that there was not a control - one of the pots not having any sealant.
But he doesn't test against an untreated pot? This is testing sealing methods against other sealing methods.
One thing my potter suggested was to submerge the pot in warm soured milk, then after a couple hours to wipe it off and slowly heat it to another 400 degrees. So far it has worked well for me.
Great thanks for that tip.
Andy, I use ganosis: beeswax and linseed oil, about 1:1. The wax is melted in oil in a water bath. It turns out something like an ointment. I heat the pot in the oven to 150 Celsius and apply Ganosis several times with a sponge. In my opinion, it is better than starch and milk and does not contradict ancient technologies.
My next attempt will be with linseed and tung oils. Thanks for the input!
That is probably also most similar to the Howard's.
This is a very interesting and thorough experiment. Over the years I've used a few different techniques to seal some of my clay pots. One of the first pots I ever made I sealed with small leaf soap root. I smashed the root with a stone and smeared the sticky substance all over the interior of the pot. Since then I have cooked in that pot and even used it as a flower vase to hold cut flower stems in water and it has never leaked even a drop. Then I used melted beeswax and that worked excellent as well. More recently I experimented with cooked palo verde beans which are similar to the soap root because of the high mucilage content. The sticky viscous mucilage seals the pores very well. Another method I recently experimented with was soaking the pot in water for about eight hours, letting it fully dry in the sun, then rubbing coconut oil all over the pot and finally filling it with boiling hot rice water and letting it sit for at least eight hours like that. Then I heated up the pot of rice water and then dumped it out and thoroughly cleaned the pot. This method works well too. Pots that are used for cooking will continue to block the passage of water as the fats and minerals in the food clog up the pores of the pottery.
Thanks for sharing your experience Chad, this gives me some ideas that I haven't yet tried.
@@AncientPottery You are always welcome. I think that there are a lot of techniques that simply died out with the ancients. I imagine that different groups used a variety of different techniques.
@@ChadZuberAdventures I'll probably experiment with some of my home-made conditioners to see if this helps improve them
Interesting!
I was wondering about chia seeds too...
An alternative to weighing the bowls, if water loss is all you're interested in, is simply to cover the top of the bowls with a plastic wrap, so that any water loss and evaporation take place through the walls of the pot and not the surface. If you were back east, it might not be such an issue, but it our dry desert air, evaporation through the water surface will definitely skew your results.
yes, I didn't think about evaporation until after but no doubt I lost a good deal that way. Next time.
Ah,this was the answer here
I am also missing a control group without coating
You could also use the glass measuring cup as a control if you dont want to cover them, because you know the glass won't absorb or leak. This will help in determining how much loss was due to simple evaporation.
evaporation shouldn't really skew the results since water would evaporate from each bowl at the same rate
Andy, this is absolutely science. This is pretty much the definition of science. Science doesn't have to be done by people with PhDs in a lab, it can be done by normal people with household resources. When we forget that, we hand over all our power to the "experts".
Well I get tired of people wanting me to measure more accurately, I really don't care it it is down to the last milliliter because I am just demonstrating that it works, not trying to quantify exactly how well it works.
@@AncientPottery I think that people are concerned with which one works best.
@@jameslarson4092 that’s why I did a simple comparison, to show which one works best.
There is no negative control, a bowl following same procedure but no sealing. So not rigorous enough for science. But as Andy stated we just want a guess
@@bastb6326 A COMPARISON not a guess. I could have saved a lot of effort and just guessed without even making the bowls.
There are so many questions and so much interest in this now. Something that time has forgot. Thanks for another look, comparisons and choices.
Thanks, glad you liked it.
As a First Nations here in Canada experimenting with this, I always have it in the back of my mind of how my ancestors may have done it. I feel like a cooking pot, for example, after weeks of cooking meals in them would naturally get it's own sealing from the moose meat, or plants made in the pot. Much like how you season a cast iron. A "good pot" would be one that survives the first few meals and slowly builds up it's own seal through use. The speed in which the water seeps out would be inconsequential to get past those first few meals. I was also thinking that my ancestors use of starch to seal pots was not like they had a bucket of starch sitting around for this, but again as a few meals were cooked in it the starches from the foods would seal while it was in use. These are just thoughts rattling in my head after reading this and I will definitely make a pot that I can test this.
Thanks for sharing your ideas. I don't seal cooking pots but allow them to seal naturally. But for an eating bowl or a drinking cup it is a little different.
Very interesting! I just wanted to point out that the edible version of linseed oil is flaxseed oil., in case you wanted to give it a try. I def will try it myself sat some point
Thank you, I am learning as I go, great to know. I probably could have found that at the grocery store. Oh well that leaves me something for a future video.
Raw Flax/ Linseed aren't drying oils, or at least not for months. Boiled and Polymerised Linseed Oil will dry quite rapidly. "Boiled" is made by the addition of chemical driers which are not food safe, they contain heavy metals. Polymerised is made by heat treating and is food safe.
Polymerised is often sold as "butcher block oil". You can make your own polymerised linseed oil by sun curing flax oil, but it's generally not recommended to try heat treating at home. Things can go boom fairly easily.
❤ wonderful. I make cooking recipes and I use my clay pots. I sealed the pots with vegetable oil. Also with bee wax
This seems similar to curing a cast iron skillet. Have you tried using cycles of high heat to polymerize the oils into the surface of the bowl?
very much like that and no I have not tried that yet
Well done 👍🏻. I would also like to have info in celsius, grams and etc. for us who watch in Europe 🙏🏻 You reach far with your informative professional productions. Thanks!
Thank you, I try to keep that in mind, but I do sometimes forget.
I love your scientific approach to figuring things out. If you aren't a teacher, you ought to be. You'd be such a fun teacher.
Ha ha, you’re funny.
I don't know if you need to do this again, since you've done a couple. But if you do, you might also include a glass or plastic bowl, so you have a reference for the water it loses do to surface evaporation to compare the others to. Also potentially weighing the water to be more precise than eyeballing. But currently the differences seem large enough that you may not need to be that precise.
Yep, I wish I had but I will do this in the next video where I try out linseed and tung oils.
Wow. Just discovered your channel researching how I might make some pots with my great grandchildren this summer. You are the Bill Nye of the primitive pottery world. Pure science.
Thanks you and welcome aboard.
Thanks for watching and checking out the comments. I just created a new playlist of all my pottery sealing videos that you can check out here ruclips.net/p/PLxjk09ZJzrltJncUQcyvtdVjLlM9QFi55
I am looking for an alternative to lard !
@@OBEECHI1 I'm curious as to if coconut oil will work.
If you repeat this experiment, could you leave one bowl unsealed so we can see how well the sealed pots hold water versus a baseline?
Crisco?
yes that would have been good but also a bit science-like
Man, I wish I had the discipline to learn this skill. Even those basic bowls are incredibly beautiful.
You can do it, it's not all that hard
I just want to thank you again for these videos.
I was able to get a little bowl made from clay from my yard. I've wanted to try this for some time.
Never would have got it if you hadn't taught me the importance of sand in the clay.
Now I want to make a nice bowl .
Thanks again
Wonderful! Keep at it and you will get better
Another great video, very interesting, thanks Andy. It could have also been interesting to have had a bowl not at all treated to see the water loss too
Great point! I thought of this after I was done, duh! Next time for sure.
Im glad you revisited this
Great 👍 Video of 4 ways to seal your earthenware pots. Loved when your beautiful 🐕 dog was drinking her cornmeal 🥛 milk treat! So sweet. Thank you, Andy. You pottery work is beautiful.
Thank you so much 😊
I am absolutely fascinated and delighted I found this channel! You're very knowledgeable and you teach so efficiently; love it 💚
Man. This is seriously inspiring. Great info man, and much appreciated!
Glad you enjoyed it!
This is a great video and exactly what I was looking for. Very well done. My thought on why to weight them is to know how much water absorbs into the pot. If I have a liquid that can spoil, I don't want a lot of it seeping into the pot and causing problems.
You're an excellent instructor. This was very helpful. Thanks and your work is beautiful
You are so welcome
Flax seed oil is linseed oil but intended for cooking. I use it to seal wooden spoons.
I will be using this in a future video on this subject. Thanks
Thank you so much Andy! I am looking to seal high fire, cone 10, marbled clay pots. The color of the clay is so beautiful that I don't want it to be hidden by the glaze but I want it to be safe from oils. This is such a perfect solution. Thank you for all the helpful information you provide. Much appreciated.
Glad to help
My general thoughts on the lard would be to treat like a cast iron pan, as in lots of coats and heating to polymerize.
I have a low casserole type bowl that developed a Crack in it, but didn't break. I used it inside a crock pot heater to re-melt left over candle wax to remake candles with. The wax re-sealed the crack and now I use it as a water dish for the animals.
Sure wax is great as long as it is not used for cooking. Thanks for your experience.
Just watched the outdoor sealing test a few hours ago. love how you experiment to learn more about your craft!
Thank you very much!
great info btw. this was exactly what i was trying to find out.
That oil sealing stuff you rub on the pots makes then look shinier and brings out the colour too! 🙂👍
Yes it does!
Thank you. Great video. One thing I would say, that I always advise is never use soap or detergent of any kind to clean no matter how dirty they get. A scouring pad (non impregnated with soap) and water. These pots are porous and will retain the taste of soap making the food yuk, so water and elbow grease only.
Great tip. Also if you are sealing with oil or grease the soap will remove your seasoning which is why they often advise to never wash cast iron with soap.
Ancient peoples figured this out centuries ago…so amazing the knowledge lost and now you are sharing it on the Internet! Thanks!
You're welcome
I love your channel. I'd love if you also added a plastic bowl and an untreated clay bowl for comparisson
Thanks
very nice information thank you!!!!!
You are welcome
This has answered all my questions lol. Thanks
in japan we have a glaze method with a kiln firing technique with rice straw!
thank you for the informative video, i really enjoyed it ^^
Thanks for the info
Great video! I am so grateful I stumbled upon your channel!
I'm sure a bazillion people have already said this but I think this is a really good experiment and it's a lot more scientific than you give yourself credit for. The only thing I'd change is evaporation. If you do the experiment again you could use a bowl of the same size with two cups of water to compare how much evaporated. You could also cover all the bowls (including the glass or metal bowl) with plastic wrap with a rubber band.
If you have permission, I would like to give you a recipe.
In order to insulate the pots, the Turks spread sheep's tail oil on the surface of the pot after cooking while the pot is still hot, thus sealing it completely, then it is baked or cooked on the stove for a while to remove the odor. I love watching your videos, thank you for these beautiful videos you shared.
Thanks so much. Really useful information and delivered in a succinct way with no waffle! (For me you didn't have to justify yourself over the weighing thing.... like you I just want a sealed bowl at the end of the process),. You definitely explained this very well, with some simple usable methods! 👍
You're very welcome!
Great informative video Andy.
Thanks
I love your videos! Keep up the great work!!!
Thanks
I am really into gardening and I started researching pottery making and I ran into you. I am so grateful. I feel like this is a tremendous resource because the terra-cotta pots are so expensive and have mini gardening friends that want to use the under ground terra-cotta porous containers and I’m wondering if I could experiment with some of these with plants that don’t need as much water is versus the plants that need more water and this is perfect for absorption. I hope to try some of these methods on the parts dispersing more or less water!
Thank you very much!
Thank you for all your research and work you share with us so we can learn from you!! 👍 😊
My pleasure!
Andy, the reason I am interested in exactly how much water is lost to absorption is because I don't intend to put water in my pottery, but rather food, juice, beer, wine, etc. I want to know which sealing method is going to absorb the least amount of material. Material lost to evaporation is a given and not of concern to me, because liquid evaporates the same regardless of its receptacle. Thank you for making these videos, they truly are awesome!
I saw a lady use some sort of spray on liquid quartz, might look into that
Actually, what you are doing here is, by definition, exactly science. :)
I'm enjoying your videos and going to do a project with my kids soon! I would have loved to see a "control" (bowl with no seal) to see how much that would lose. Thanks for your videos!
Great idea!
I love all your videos. You are amazing!
Thanks
Watching your video reminded me of something. In certain places, animals even fight for access to specific clay wells. It is well-documented that many animals incorporate clay into their diet. Interestingly, the use of clay in human nutrition has a long history and remains somewhat of a puzzle for modern science.
I understand that the primary purpose of using a sealant is to prevent food juices from seeping into the clay and becoming rancid. However, this made me wonder if there is any direct nutritional value in consuming food cooked in unglazed clay pottery. Since some clay particles inevitably end up in the food, it seems unavoidable. Lastly, I want to express my sincere appreciation for the insightful and educational video you shared on your channel. It was not only entertaining but also incredibly informative. I truly enjoyed watching it and gained a valuable new insight about the use of clay the made me move on from the kiln oriented process. Thank you.
I would recommend Mahoney's Walnut oil. it's a polymerizing oil, it will soak in and polymerize on it's own; that's the big problem with mineral oils, they don't ever really polymerize. (Mahoney's is foodsafe finish btw; I use it for my wooden lathe-turned bowls) Give it a try if you ever revist this; i'd be curious how it compares..
All i can think of is yugioh lol
Thanks Tim, I will do this with my next video on this subject
Or just mush up a walnut kernel and use that to oil whatever you want. Walnuts have a way better shelf-life than walnut oil that slowly polymerizes and acquires a rancid taste. It is also cheaper and more easily found.
@@dragoscoco2173 Mahoneys has been processed (mostly by heating and filtering) so it polymerizes more quickly and won't cause an allergic reaction the way "raw" oil from walnuts will..
@@timhyatt9185 I do not doubt the excellent quality of processed oil. Just that it is sometimes hard to find, expensive and unless it is diluted with an industrial solvent (basically making it for technical use only) it will polymerize once you expose it to air.
I have personally used walnut kernels to oil many wooden products as big as a bow stave, drying in about a day. And even there i did not require that much oil, about a spoon, and because I seem to never run out of walnuts I just find it personally convenient. Your experience may vary :P.
Another great and interesting video, thank you🙂
Thanks
My Walmart carries food grade linseed oil, near the olive oil. It's labeled as "flax seed oil" but it's all the same. I bought some to use for seasoning cast iron ware. Freshly pressed flax seed oil has been used in northern Europe to flavor food - quark and other bland foods.
Yeah, I just learned that since I made this video. I should have looked at the grocery store instead of the hardware store. Anyway it gives me a subject for a future video. Thanks!
@@AncientPottery You're welcome. Happy to help, even in little ways.
I willing to bet that they used a bucket of milk to submerge the clayware (i.e., a bucket of milk was fresh milk, sitting, and they just submerged the pottery, then used that milk later for cheese, etc) and the starch? They cooked a big pot of starch, then submerged the pots, then kept it cooking the remaining starch for glues, or even to thicken other foods, maybe candy. My overall impression is that nothing would be wasted from anything in the past....much different than how we live today. Its sad, but I am glad you are explaining these principles to us today. Thank you!
good , thanks!
Another great one mr. ward. Could you do a video of trying to seal earthenware using dextrin? It’s corn starch powder that is baked until a light brownish color, then used as a binder for granulating black powder. Thank you from the doobly-do.
Sounds interesting, I will have to see if I can get my hands on some of that
@@AncientPottery I’ve always made my own from a box of store bought corn starch. Thank you immensely for taking the time to respond to a subscriber. I look forward to you future videos. From the doobly-do sir, thank you again
Very interesting Ty. What about bees wax ? I didn't think of linseed oil as well . Great Info
What temperature do you use for the „preheating“ in the oven?
And thanks for your great content! :)
First off I just want to say I appreciate your channel. I took a couple of semesters of ceramics-focused art classes in high school years ago but was always leery of the monetary investment in ceramics on my own. Thank you for helping show that you don't need hundreds or thousands of dollars to start making things.
I would also opine that folks commenting on weighing your vessels were likely talking about weighing the empty pots pre-test and then re-weighing after the water was poured out to see how much the ceramic absorbed. Measuring the total volume lost doesn't differentiate between the angels' share and the devil's cut, so to speak.
Not sure if this is an experiment you'd care to repeat or if the scale you have at hand can measure in small enough increments to tell the difference, but I offer my thoughts. Thanks again!
Thanks
I really enjoyed this video, but I really wish you would show the untreated clay bowl so we could compare....but what you are doing is science in action...so interesting and so cool!
Food grade linseed oil - also known as flaxseed oil, should be available via a health food store, or large grocery store.
Thanks, I'll try that. Also I just learned that 100% pour Tung oil is food grade too.
@@AncientPottery Tung oil is only food safe when it's fully cured, usually around two weeks. Careful! Uncured Tung oil is very toxic stuff if ingested.
@@TheBoldImperator thanks for the tip. Look for a future video.
@@AncientPottery beware that good safe linseed oil doesnt polimerise.
Linseed oil has to be cooked ( activated) in order to polimerise and that is not food grade.It is used for cutting boards thogh.
You can also melt wax and mix with linseed oil while its warm to get a mix with more wax and less oil.
When i sealed with milk I had to bake at higher temp to change the milky colour to coppery brown with a sheen. It was mostly effective, except where coarse bits of temper created "pathways" for luquid to seep through.
I was listening to a Tudor England documentary concept where they said they used sour milk during the dealing process because the chemicals you refer to were more abundant in sour milk.
Thank you Andy. The weight results helped me to see that Milk sealing beat out all the competition. The volume loss of Milk was similar to the results from the Howard's, yet Howard's appears to have allowed a greater amount of water to pass through the bowl. Milk sealing seems to have given the bowl a greater ability to retain water within the sealed bowl, meaning the water was still retained despite being locked into the structure of the bowl.
Thanks. I was also very happily surprised by the effectiveness of the milk sealing. I suppose multiple coats might result in an even better sealing too.
Great test. Thanks! :)
You're welcome!
Thank you so much for your videos! I am learning so much, and I love your style.
I have a question. After you seal your pottery, do you need to seal it again in the future? I am thinking like how after you use cast iron you need to re-season it every time. Does pottery need re-sealed after it is used for food?
Heh, I think that the responses to this kind of video really show the wide appeal of this channel. Some people are artists, some are interested in the history or re-creation of it, and some (like me) are more interested in the technical aspects of pottery.
So it's understandable and tempting for me to go "ooh, try this... ooh, measure that!", or even to correct how the comparison happens, but that's not always the most helpful thing to do. Shoot, for me personally, I LOVE hobbies that require measuring precisely, like espresso or homebrewing or baking... but that's not necessarily fun for everyone else
So in short, thanks for the comparison, and also it's fine to set boundaries concerning your methodologies. Shoot, I kind of want to try out some sealing methods myself!
One of the techniques I've read about was putting dried corn cobs in the pot, then sealing the pot and sticking in a bed of coals. The pot gets very hot, and the cobs start to scorch and smoke, but so long as no air gets in, the oils won't ignite. The resulting smoke seals the pot. Another issue was adding physical designs to the pot, such as checkered and lined patterns. It wasn't just to make them beautiful, they also increased the strength by interrupting potential shear lines.
It seems every culture has a different technique. There are many ways to do it
As a few alternatives depending on what you want to call native or local, coconut oil is great to work with as it warms easily but can take a fair amount of heat, but even with a light braze of 600*F it will taste nice afterwards. Food grade carnauba wax is often found in a lot of bamboo wax conditioners and I've used that on a lot of cutting boards. In conjunction with the coconut oil on coffee cups and repeat heat cycles, I could see that being rather nice.
The third and perhaps most universal for historical purposes, roasting coffee beans releases an absolute jewel of an oil that penetrates metal (all my roasting pans for coffee beans take on a golden brown hue) and I may try lining a once-fired piece in green coffee beans to see how that goes. Wouldn't that be a honey of a selling point for an earthen coffee cup!
Add: Ah, almost forgot. Casein from milk was used historically for bioplastic production in conjunction with another material which escapes me at the moment, but possibly a guar gum. Might be worth a read. Casein can be found in powdered form as it comes back and forth into the sustainable products fashion every few years.
Thanks for the info. That coffee oil sounds perfect for sealing a coffee cup, I wonder if that can be purchased somewhere?
@@AncientPottery I get green coffee beans and roast them myself every few months but have built up a nice little collection as you do. I'll send my supplier of choice in your kiln email later tonight.
Thank you 😊
You're welcome
Food grade linseed oil is often sold as flaxseed oil. It isn't the same thing, but walnut oil can also be used in the same way.
Thanks for that
Thamk you !
This is great science! Just a thought for your NEXT sealant video (do several, we obviously like them and you're doing great): Make each bowl > apply the sealant to each bowl > note the weight of each bowl dry > add the weight of one cup of water (240g) to each bowl (place dried bowl on scale, tare scale, add 240g of water) > note the weight of each bowl with 240g of water > let all the bowls sit for X period of hours/days > place a new/different glass container on the scale and tare the scale to zero it out > pour one bowls water into the container noting the weight of the container in grams > weigh that same emptied bowl, noting it's weight in grams > clean/dry out the glass container > continue this process with each bowl until the experiment is complete.
This will provide you with the following:
Beginning results:
1. The weight of each bowl
2. Constant = 240g of water
Ending results:
3. Precise water that was held/emptied from each bowl (the added weight in the container with each bowl's respective water)
4. Precise water retention/absorption from each bowl ("emptied bowl weight" minus "dry bowl weight")
5. Precise evaporation from each bowl. (240g - (#3 + #4) = The evaporation coefficient
Isn't science the coolest!? This isn't much more work than what you are currently doing, just more accurate. 😉 If you have time and looking for more content for your channel, please humor us with the above experiment by trying the same or different sealing products/methods.
I love learning, keep up the good work.
I love the fact that you are a not nonsense kind of guy. Weighing the pats doesn't tell you the story measuring how much water is lost does.
I know that you like to use natural earthware but I will like to see you do a salt glazein one day just to learn how it's done.
Salt glaze does not go with earthenware. You need temperatures of at least 1300 C to get salt to form a glaze, that is kiln temperature, not primitive pottery temperature.
Thank you for taking the time to reply. I am planning to build some type of kiln that runs on charcoal sometime in the future I am too busy right now.
Unglazed terracotta makes a great water filter. What do you suggest for sealing coffee mugs?
Beeswax or pine pitch check out this video ruclips.net/video/-GOfY4inaMw/видео.htmlsi=s-u4A3fiz6y3tNhS
fantastic. Thank you Sir.
Most welcome!
Be aware, if you try linseed oil (you can get it at health food stores as others have said) food grade does not have drying agents, so it takes 2-3 days between coats (since it's not technically "drying"), at a minimum to let it set. And it could be a couple months to fully polymerize, depending on how thickly you apply it. But as long as the surface is solid, it should be useable, even if the core is not fully cured.
Not if he uses the cast iron seasoning method to polymerise the oil with heat. Dress the bowl stone dry with food grade flaxseed oil in a thin layer. Heat in a 400 degree F oven for 2 hours, and let it cool. Much like the pans, repeated treatments improve the seal.
@@BigHenFor Yes, heating accelerates the process, but heating in the presence of oxygen tends to discolor the oil. And if you exceed the smoke point (225 for unrefined linseed oil) it will carbonize and turn black, which is exactly what you want on a cast iron skillet. Probably not so much on pottery. Of course, just for testing purposes, color is irrelevant.
Side note though, you can use polymerized linseed oil, it has been heated without oxygen to partially polymerize it and speed up the process (without discoloration). It's not marketed for food use, but it IS food safe, as long as there are no additional drying additives added.
I will add though, I have not tried it on pottery. Iron is a natural catalyst to the oxidation process, so linseed on pottery will respond differently than linseed on iron.
Thanks for the tip. The conversation below is very enlightening. I will be doing a future video using linseed and other oils of that sort.
@@krahnjp And it depends on the iron oxide content of the clay too. But for Cooking, which was usually over wood, the pots would get black on the outside anyway. However, if you notice that when put in an outdoor kiln, the heating of the clay produces very little contamination, so it might be possible to process it in the kiln and avoid blackening using the polymerised Linseed Oil as you say. Or, even using a charcoal fire if built to isolate the pots from the Ash.
Hmm. Those medium-sized bowl-shaped pots on the thumbnail, and the ones you fire on the video, look like they'd make PERFECT vessels for biggish handcrafted scented candles, the kind with several wicks! I honestly don't know if they would need sealing for that. Have you thought of selling to/doing a collaboration video with that kind of crafter? 🙂
This is most certainly science. It may not be the most accurate science with several variables that weren't tightly controlled, but...
You came in with something to prove, proved it, and most importantly, documented it. This is science. Someone can now take this and replicate it because it has been documented.
That is very interesting!
Glad you think so!
Great test, thank you for showing it. Is it then a conclusion that lard doesn't seal that well as other sealants, since water went through the bowl?
I have a good friend who uses lard to seal his pottery and loves it. He also doesn't try to polymerize it. I think more experiments are necessary.
I like the look of the milk residue
yeah I guess it has a charm to it.
Andy thank you for these videos they are great and I've learned a lot from you. I'm curious if heating the pots up enough to absorb bees wax would work the best. Or any wax for that matter but I guess bees wax was also available traditionally. What are your thoughts? Cheers J
No bees wax was not available traditionally because North America did not have honeybees before the Europeans brought them across the sea. But it is definitely a good sealant for not cooking pots.
@@AncientPottery thank you so for replying. That's very interesting. Lastly would you consider graphite to seal it as graphite is hydrophobic and easily absorbed into to porous surface. Graphite obtained by charcoal?
@@joshuadelisle I do t know anything about using graphite. You will need to do some experiments to find out.
@@AncientPottery thank you. An idea for your videos maybe. All the very best. Cheers J
Many places in Mexico will rub the pottery with garlic, then lime powder (should be good grade)is heated and brought to a boil with the whole pot being rinsed in the lime solution. Sometimes even baking soda is added too. In Spain, they rub the garlic then boil vinegar to cure it
I have heard of this but can't imagine how garlic would help to seal the pores. I would like to learn a little more about the science behind this practice.
@@AncientPottery The science behind that, is that garlic makes everything better.
... also garlic contains a substance, that comes out, when you press it. First it is soapy, but when it gets warm or has air contact for too long, it gets sticky. That is why you clean your garlic press soon, and with cold water.
To be more precise: Garlic contains alliin, a sulfur containing amino acid (amongst others), which quickly decays on air contact or heat. When it does not, it can form pyrroles (one of those organic ring molecules) with other common amino acids. Those pyrroles, under acidity and heat, can form polypyrroles. That are organic polymers.
So it seems plausible, that the described method could causes this. Rubbing in the garlic, releases alliin. Lime powder solution or vinegar adds acidity and water. The heating in acidic solution then finalizes the polymerisation. Since alliin is so unstable, all that has to happen quickly. That's why you rub in the fresh garlic, directly.
Generally sealing earthenware, not only bases on the plugging of pores, but plugging them with hydrophobic substances, like wax, fat or polymers. Polypyrroles, were e.g. used to make silicate hydrophobic. That's another argument, that it is plausible, that this might also work on sealing earthenware.
Very interesting to see. I wonder if you reheated them in the kiln if that would seal them better due to the heat or whether it would burn the sealer off completely. Maybe able to test that in another video?
Learning a lot here - Thank you for the videos are awesome! btw, please give to the dog a good food :)
Good job on test. Only thing might be different is the milk was probably raw with lots of fats and cream. could make a sealing difference. Plus they probably sealed up with use. 👍
Something I use for wood cutting boards is 100% Tung oil. It takes a while to dry but it hardens in the wood. Sometimes I'll cut it with mineral spirits for things like end grain cutting boards and you can actually just keep applying on the top and it will eventually go through to the other side.
That might be worth trying, thanks
@Andy Ward's Ancient Pottery if you want food safe, make sure it's 100% the stuff at the hardware store labeled tung oil has a bunch of hardeners in it that are not food safe.
The reason people are wanting you to weigh the bowls is that it gives you a more accurate indication of how much water was lost. Some water sticks to the bowl, and therefore isn't accounted for when you measure purely by volume.
In this case, it's probably needless precision. It's not like you're testing the claims of a commercial products to see if they're telling the truth. This is simply, "Of methods A, B, C, and D, this worked best for me."
If those people want high-precision measurements like they're discussing, they're perfectly welcome to do the test themselves, and make their own video about it if they so desire. I can think of a couple things I would have done differently in this test, but if I want that information so badly, then I can do my own tests, too!
It seems like some people are thinking of you as if you are some paid instructor, who needs to spoon-feed them every bit of information. You're not. You are giving people a starting point and helpful advice. There is absolutely nothing stopping your viewers from trying out ideas on their own. If someone wants to know if they can mix horse pucky into the clay to achieve some specific goal, then they should try it!
One of the best ways to learn is by doing. Watching videos can give you a starting point, but people really need to try it out for themselves.
Thanks
I future experiments I would also have water in the measuring cup as a control to see what's being lost to evaporation & what's seeping through the bowl.
yeah I should have measured the evaporation. Next time.
we use traditional y القطران katran for olla قلة mainly for drinking
and try bees wax or honey wax same used for candles if you don't just burn candels in it
Thanks for the tip.
Comments for the algorithm. Good video thanks for making them, I be interested I you could treat them like cast iron as some others have suggested.
Another method of milk soaking, is one I saw where after the oil lamp, in this case, was fresh out of the fire and still hot, he submerged it entirely into a big bowl of milk, and let it cool off there. I have not tested this at all, but with nothing but my intuition to guide me, seems like you could achieve better results maybe? I have not tested it at all, but at least I imagine you wouldn't get that line of milk residue where the surface was, and it'd get evenly coated.