I recently took a furniture making class and the discussion regarding shellac was to mix the flakes with denatured alcohol using whichever ratio (pound cut). I finished a nightstand with shellac which was in a plastic squirt bottle. I applied it with a pad made from a lint free cloth. The shellac had been mixed the day before and we were told it had a 3- month shelf life but should always test it before using on a scrap piece of the same wood. I thought the squirt bottle was brilliant because the opening is quite small preventing the evaporation of the alcohol. I live in the states, btw. Hope this helps.
Ive read Shellac goes bad by a process called esterification. When wanting esterification to occur you expose it to heat and use a drying agent to remove water content. Since the presence of water can reverse the esterification process. So to prevent esterification I assume a little water is your friend. But humidity and water content could increase drying time. Pure ethanol is hygroscopic. I dont think there is an equilibrium point. I believe it will absorb water from the air and continue alcohol evaporation until all of the alcohol has evaporated and only the water fraction remains.
Hi Susan. This popped up 5 years later into my news feed for some reason! I love that you took the time to try this. Not scientific but I admit I was curious to see the result. Thought I'd add my two cents, although you may know all of this at this point. I now toss shellac mix out after a year whether it's gone bad or not, but I have never had any go bad prior to that, and some has lasted much longer as others note below. Interestingly I HAVE had flakes go bad. In two cases, de-waxed flakes that I had for 3 to 4 years did not mix with alcohol at all, and I had to toss all of the flakes. Those flakes were stored like all my others, sealed in a canning jar in a dark place. This was odd to me since other flake of the same age mixed just fine and applied fine after mixing. I later read that ultra-light shellac (like bleached blond) has a shorter shelf life in flake form, possibly due to the treatment required to bleach it. My flakes that went bad were indeed ultra blond. All that said, it's possible the flakes were just old when I bought them. As one comment below notes, you never really know how old flakes are (or hardware store-bought pre-mixed shellac) before you buy them. I spoke with the manufacturer who confirmed that flake does have a limited shelf life, although longer than the shelf-life of the mixed stuff. I realize I am a bit of a shellac-aholic, but I also sometimes buy button lac which I was told had a longer shelf life. When I mix this I typically settle out and/or vacuum-filter out the wax (although you don't have to depending on your application). It's more orange in color but you can adjust this by filtering through varying amounts of activated charcoal. That's a lot of ridiculously unnecessary fuss though and now I only use it if I am making traditional violin spirit varnish, where the color and the wax are wanted. For guitars, it's better to just get a fresh batch of dewaxed flake from a trusted source. Side notes: YES!!!! Alcohol evaporates out rather quickly, changing your 'cut' if left open too long. It also sucks in moisture from the air. Never keep your shellac (or your spirits) open any longer than you have to, and if possible, store in a smaller container as you use it to limit headspace in the jar... Since I can't test the seal on glass jars, I store my mixed shellac in plastic containers like lab squirters or ketchup bottles. A lot of these aren't air tight. Test this by squeezing when closed. If it leaks, you can sometimes fix by stretching cling film over the top before you screw on the cap. Lastly, before I use an older (or suspect) shellac mix on an instrument I'll apply to a piece of scrap. If it isn't dry to the touch in a few minutes it goes in the bin. That's a pretty reliable test. All the best!
Shellac, made from the secretion of the Lac bug, dissolved into a liquid by adding denatured alcohol. As there are really just two parts to this, Lac resin and alcohol, revitializing the shellac that has gone past its shelf life should be as simple as adding small amounts of alcohol back into the equation.
I've used shellac up to 2 1/2 years old, but I have also used shellac that has turned. It's fairly easy to see if padded shellac will harden (and if it does quickly, then no problem). The problematic shellac that I had wouldn't harden at all, it was gummy. It's very easy to tell if it's no good, and easy enough to test any around. I suppose if there is a speed need, then one could find some that cures, but not fast enough for them. I am, perhaps, cheap, but also don't like to throw away supplies that are still good by some arbitrary rule. One day, I may be burned by that, but other than learning to test older shellac first before using, I haven't. The cost of the turned knobs that I made was only to strip the finish off with alcohol and refinish the knobs.
Thanks for the video! I've never had any luck using "shellac in a can" so tonight I made my own using fresh dewaxed garnet flakes (I got off of Amazon ) after I watched this video. After I measured the alcohol and flakes I needed I mixed it all together and shook it good for over an hour until it dissolved.It didn't clump. After that was done I applied 4 thin "test" coats on a pine board I'm using on a loft bed and the shellac went on smooth and dried fast between coats!! This is much easier to use than "shellac in a can" and dries faster.I've read that dried flakes kept in an air tight container(not metal)in a cool dark place will last many years and years while shellac in a can is only good for 3 yrs if unopened and 6mo to a year after its opened.
Patricia if you are using shellac (or French polish) people who talk about this leave out some important facts. The applicator for starters, how you apply it, the different coats are of different thicknesses, method of applying is very important and the applicator what to use and how to make it. With all of this, where you are has a big effect on this (temperature and humidity) and don't forget the type of wood. there all different , Get a copy of the "Good Wood Book"
I use the methylated spirits with red/pink coloring to it with my shellac, and I am quite confident the color evaporates with the spirits. Also I have used shellac that's been sitting in the window sill for over a year, and still been good to use. Granted it is bellow room temperature in the shop most of the year, but not freezing cold. Without actually measuring the temp. I would say it is between 10 and 20 degrees C normally. I always do a smal test patch fist though. If it seems to be drying nice on a piece of wood after ~20 min. I'll use it.
Humidity makes a difference, even for closed containers. I'd love to see this experiment padding the shellac (a few minutes each batch) onto both hardwood and softwood, i.e., backs-and-sides and soundboards. Thanks for this video!
+Scott Reeves Great comment. Alcohol takes on moisture each time the lid is removed, and equilibrates with the air at 70%. It might start at 96%, but don't expect it to stay there. I use the bottom half of my alcohol bottle in my fondue burner -- not in shellac.
+Nora Bowlby it does not so much take on moisture as evaporate differentially - the alcohol vaporizes faster, lcausing the water content to rise especially if you leave the can/bottle open during polishing.
+evanherk Very correct. Both processes occur. The bottom line is that equilibration is at 70% and is better for fondue than shellac. It's a standard we use in biology labs for making other solutions, and because of it's stability we have a known starting point. And then there is cost.
The answer is simple, just mix the right quantity for the job. starting from a baseline quantity, It only takes minutes to dissolve 16g in 48g of Methanol, you don’t need to bugger about with using blenders to grind up the flakes and 24 hours waiting time if you used a lab grade 99.95 Methanol which I did recently. Why would you keep Shellac about the place when it can be mixed instantly?, and if you want to save money buy the smallest amounts of Methanol instead of big bottles of the stuff which evaporates over time in storage.
As has been said, alcohol absorbs moisture. Seeing that your jars are of different sizes and fill rates, the fresh one has a huge advantage against the rest, at least speaking about oxidization. Having had the samples stored in full jars would make an interesting comparison.
I agree also to be scientific all shellac flakes should be mixed with shellac from the same batch of flakes....other wise I think it is like trying to show some thing about a species of wood and using wood (say pine) that is from different locations (ex: pine from New England will be much different than from No Carolina.
Just make a fresh batch and use it within a week of applying it. Aclimate both wood and shellac to the same temp over night. Are you sure about your ratio? I read 4:1 is best so 8oz alc. to 2oz flakes. I think you dilute more, which might also be why you have a shorter shelf life.
I just did part of a project (the fret board for a lap steel I am building) The fret board is Vietnam Coconut wood. I believe that the most important thing is not when it was mixed but how it is stored and how it is put on.....making the proper rubber (applicator..don't want this to be X rated) I also think it is not a good experiment because glass doesn't have the make up that wood does (as they say comparing apples to oranges)...Since my guitar will be three different woods it will be interesting to see how it comes out
When I was 18 years old, I decided to sand the chipped up red finish off my 1961 Gibson Melody Maker. I found an old can of shellac on a basement shelf, applied a generous coating, and hung it with a wire from the joists. The next day it was still very tacky. The next week it was still very tacky. Then the termites swarmed. Once the infestation was eradicated, I scraped the bugs off (it was completely covered in them), and rubbed down the still tacky shellac with a rag. A month or so later, I could handle the guitar without it sticking to my hands or clothing. I put the hardware back on. Flash forward 42 years, the finish is holding up wonderfully. Short shelf life? Hmm, maybe so.
@Andrew Seniuk That was a post from a couple of years ago, goes to show nothing ever disappears from the internet! There's no traces of the bugs, looks like a nice, hand rubbed french polish. I was young and dumb, now I'm old and less dumb...
What exactly does it mean when it goes bad? Does the lac resin fails in its material properties? If its a matter of the alcohol content evaporating, simply top up with more alcohol (use the denatured industrial stuff, not the medical ones that has emollients added). Of course, if a lot of the alcohol has evaporated after long storage without topping up, then it will turn real gummy, re constituting it would be a beast. Otherwise, I assume that the producers would want consumers to buy fresh batches continuously to keep the sales up. If you have the Zinsser stuff, note that the stuff could eat through the can and leak at the bottom.
First thing I noticed is the variance in colors. This clearly means there's a difference in cut of the shellacs. Secondly the test doesn't represent actual application of shellac. Glass reacts differently from wood, first and foremost, wicks. Second glass only has one side which evaporation can happen. I'd say recut if needed and if issues are happening it's likely a problem with application or cut versus the shellac itself. Good video though. I was admittedly cringing when you were testing only the thickest parts of the drops. :) You caught yourself in the end!
I think that you have added to the knowledge base. With out this information good usable shellac might have been erroneously discarded with the thought that it was no longer viable.
Well you can't get 100% alcohol, it absorbs moisture. The purple meths (there is no methyl alc. in it anymore) only really shows it's colour on very light coloured shellacs such as Platina. High purity Isopropyl is a good substitute and it's clear. Flashes off a touch slower but you can certainly French polish with it. Waxy shellacs certainly keep much longer. In the dry state seedlac and button lac seem to keep forever. If you did your test on mixed 6 month old shellac you might then see a difference. All shellacs go through a process of esterification, which degrades them. Thicker cuts keep longer than thinner cuts.
vihuelamig salt can be used to separate the water from alcohol, salt and alcohol do not mix. It's also the closest way to get close to 100% with out heat. Then there is the slight risk of salt contamination, which is doubtful since the salt and saltwater will settle down, and you could just decanter the alcohol off.
I think I've watched all of your videos now on shellac and mixing etc. Can I suggest you search Eddie Castelin on you tube and his excellent videos on "O B Shine juice". I'm not sure if its specifically for wood turners but its super easy to make and really works a treat.... for wood turning at least!
The bottles/cans on the shelf are full with little or no oxygen in them. This is a huge advantage and variable when figuring shelf life. They are also protected from light in the new cans/bottles
@@brandysigmon9066 All true, but pre-mixed does still have a shelf life. The manufacturer's know this. (I've spoken with them). They used to print it on the cans, but stopped because people were not buying the older stuff. Just like you do with milk!
Lol. Just buy high quality ready made shellac. I have used several hundred gallons of shellac and AFAIR I have only ever had one instance of stickiness, which could of been a reaction. I have used shellac that is several years old on hundreds of occasions with no issue. I am guessing the flakes are more easily oxidised and that non industrial alcohol contains more water. I have never discarded any old shellac due to age.
I use methylated spirits but mine has no color if your meth comes purple i would suggest that you going to have distill your own alcohol especially if you luthiers start drinking some just befor you belt out a tune
And how old were your flakes before you got them from your supplier? No one knows for sure. This test is ridiculous. You have no idea how old Shellac flakes are to begin with. I have used shellac that I mixed in 2007 and 11 years later it still works fine.
I recently took a furniture making class and the discussion regarding shellac was to mix the flakes with denatured alcohol using whichever ratio (pound cut). I finished a nightstand with shellac which was in a plastic squirt bottle. I applied it with a pad made from a lint free cloth. The shellac had been mixed the day before and we were told it had a 3- month shelf life but should always test it before using on a scrap piece of the same wood. I thought the squirt bottle was brilliant because the opening is quite small preventing the evaporation of the alcohol. I live in the states, btw. Hope this helps.
Ive read Shellac goes bad by a process called esterification. When wanting esterification to occur you expose it to heat and use a drying agent to remove water content. Since the presence of water can reverse the esterification process. So to prevent esterification I assume a little water is your friend. But humidity and water content could increase drying time. Pure ethanol is hygroscopic. I dont think there is an equilibrium point. I believe it will absorb water from the air and continue alcohol evaporation until all of the alcohol has evaporated and only the water fraction remains.
Hi Susan. This popped up 5 years later into my news feed for some reason! I love that you took the time to try this. Not scientific but I admit I was curious to see the result. Thought I'd add my two cents, although you may know all of this at this point.
I now toss shellac mix out after a year whether it's gone bad or not, but I have never had any go bad prior to that, and some has lasted much longer as others note below. Interestingly I HAVE had flakes go bad. In two cases, de-waxed flakes that I had for 3 to 4 years did not mix with alcohol at all, and I had to toss all of the flakes. Those flakes were stored like all my others, sealed in a canning jar in a dark place. This was odd to me since other flake of the same age mixed just fine and applied fine after mixing. I later read that ultra-light shellac (like bleached blond) has a shorter shelf life in flake form, possibly due to the treatment required to bleach it. My flakes that went bad were indeed ultra blond. All that said, it's possible the flakes were just old when I bought them. As one comment below notes, you never really know how old flakes are (or hardware store-bought pre-mixed shellac) before you buy them. I spoke with the manufacturer who confirmed that flake does have a limited shelf life, although longer than the shelf-life of the mixed stuff.
I realize I am a bit of a shellac-aholic, but I also sometimes buy button lac which I was told had a longer shelf life. When I mix this I typically settle out and/or vacuum-filter out the wax (although you don't have to depending on your application). It's more orange in color but you can adjust this by filtering through varying amounts of activated charcoal. That's a lot of ridiculously unnecessary fuss though and now I only use it if I am making traditional violin spirit varnish, where the color and the wax are wanted. For guitars, it's better to just get a fresh batch of dewaxed flake from a trusted source.
Side notes: YES!!!! Alcohol evaporates out rather quickly, changing your 'cut' if left open too long. It also sucks in moisture from the air. Never keep your shellac (or your spirits) open any longer than you have to, and if possible, store in a smaller container as you use it to limit headspace in the jar... Since I can't test the seal on glass jars, I store my mixed shellac in plastic containers like lab squirters or ketchup bottles. A lot of these aren't air tight. Test this by squeezing when closed. If it leaks, you can sometimes fix by stretching cling film over the top before you screw on the cap.
Lastly, before I use an older (or suspect) shellac mix on an instrument I'll apply to a piece of scrap. If it isn't dry to the touch in a few minutes it goes in the bin. That's a pretty reliable test.
All the best!
Shellac, made from the secretion of the Lac bug, dissolved into a liquid by adding denatured alcohol. As there are really just two parts to this, Lac resin and alcohol, revitializing the shellac that has gone past its shelf life should be as simple as adding small amounts of alcohol back into the equation.
I've used shellac up to 2 1/2 years old, but I have also used shellac that has turned. It's fairly easy to see if padded shellac will harden (and if it does quickly, then no problem). The problematic shellac that I had wouldn't harden at all, it was gummy. It's very easy to tell if it's no good, and easy enough to test any around. I suppose if there is a speed need, then one could find some that cures, but not fast enough for them.
I am, perhaps, cheap, but also don't like to throw away supplies that are still good by some arbitrary rule. One day, I may be burned by that, but other than learning to test older shellac first before using, I haven't. The cost of the turned knobs that I made was only to strip the finish off with alcohol and refinish the knobs.
Nice initiative, I liked!
I already used a 2 year old shelac mixture and I did not notice any difference.
It's trial and error tests like this that teach us things that can only be passed on from experience. Well done!
Thanks for the video! I've never had any luck using "shellac in a can" so tonight I made my own using fresh dewaxed garnet flakes (I got off of Amazon ) after I watched this video. After I measured the alcohol and flakes I needed I mixed it all together and shook it good for over an hour until it dissolved.It didn't clump. After that was done I applied 4 thin "test" coats on a pine board I'm using on a loft bed and the shellac went on smooth and dried fast between coats!! This is much easier to use than "shellac in a can" and dries faster.I've read that dried flakes kept in an air tight container(not metal)in a cool dark place will last many years and years while shellac in a can is only good for 3 yrs if unopened and 6mo to a year after its opened.
Patricia if you are using shellac (or French polish) people who talk about this leave out some important facts. The applicator for starters, how you apply it, the different coats are of different thicknesses, method of applying is very important and the applicator what to use and how to make it. With all of this, where you are has a big effect on this (temperature and humidity) and don't forget the type of wood. there all different , Get a copy of the "Good Wood Book"
I use the methylated spirits with red/pink coloring to it with my shellac, and I am quite confident the color evaporates with the spirits. Also I have used shellac that's been sitting in the window sill for over a year, and still been good to use. Granted it is bellow room temperature in the shop most of the year, but not freezing cold. Without actually measuring the temp. I would say it is between 10 and 20 degrees C normally. I always do a smal test patch fist though. If it seems to be drying nice on a piece of wood after ~20 min. I'll use it.
Humidity makes a difference, even for closed containers. I'd love to see this experiment padding the shellac (a few minutes each batch) onto both hardwood and softwood, i.e., backs-and-sides and soundboards. Thanks for this video!
+Scott Reeves Great comment. Alcohol takes on moisture each time the lid is removed, and equilibrates with the air at 70%. It might start at 96%, but don't expect it to stay there. I use the bottom half of my alcohol bottle in my fondue burner -- not in shellac.
+Nora Bowlby it does not so much take on moisture as evaporate differentially - the alcohol vaporizes faster, lcausing the water content to rise especially if you leave the can/bottle open during polishing.
+evanherk Very correct. Both processes occur. The bottom line is that equilibration is at 70% and is better for fondue than shellac. It's a standard we use in biology labs for making other solutions, and because of it's stability we have a known starting point. And then there is cost.
The answer is simple, just mix the right quantity for the job. starting from a baseline quantity, It only takes minutes to dissolve 16g in 48g of Methanol, you don’t need to bugger about with using blenders to grind up the flakes and 24 hours waiting time if you used a lab grade 99.95 Methanol which I did recently. Why would you keep Shellac about the place when it can be mixed instantly?, and if you want to save money buy the smallest amounts of Methanol instead of big bottles of the stuff which evaporates over time in storage.
A container with a tight lid and full will last longer than buggered threads and a small amount of shellac.
As has been said, alcohol absorbs moisture. Seeing that your jars are of different sizes and fill rates, the fresh one has a huge advantage against the rest, at least speaking about oxidization.
Having had the samples stored in full jars would make an interesting comparison.
I agree also to be scientific all shellac flakes should be mixed with shellac from the same batch of flakes....other wise I think it is like trying to show some thing about a species of wood and using wood (say pine) that is from different locations (ex: pine from New England will be much different than from No Carolina.
Just make a fresh batch and use it within a week of applying it. Aclimate both wood and shellac to the same temp over night.
Are you sure about your ratio? I read 4:1 is best so 8oz alc. to 2oz flakes. I think you dilute more, which might also be why you have a shorter shelf life.
Thank you for an interesting video. As someone who is just starting to mix and use shellac, I need to know this stuff :-)
I just did part of a project (the fret board for a lap steel I am building) The fret board is Vietnam Coconut wood. I believe that the most important thing is not when it was mixed but how it is stored and how it is put on.....making the proper rubber (applicator..don't want this to be X rated) I also think it is not a good experiment because glass doesn't have the make up that wood does (as they say comparing apples to oranges)...Since my guitar will be three different woods it will be interesting to see how it comes out
I get about 6 months to a batch. 2 lb cut (2 oz ground dewaxed and 8 oz Behlen Behkol Solvent)
When I was 18 years old, I decided to sand the chipped up red finish off my 1961 Gibson Melody Maker. I found an old can of shellac on a basement shelf, applied a generous coating, and hung it with a wire from the joists. The next day it was still very tacky. The next week it was still very tacky. Then the termites swarmed. Once the infestation was eradicated, I scraped the bugs off (it was completely covered in them), and rubbed down the still tacky shellac with a rag. A month or so later, I could handle the guitar without it sticking to my hands or clothing. I put the hardware back on. Flash forward 42 years, the finish is holding up wonderfully. Short shelf life? Hmm, maybe so.
Wow, I would have never predicted that!😲
@Andrew Seniuk That was a post from a couple of years ago, goes to show nothing ever disappears from the internet! There's no traces of the bugs, looks like a nice, hand rubbed french polish. I was young and dumb, now I'm old and less dumb...
What exactly does it mean when it goes bad? Does the lac resin fails in its material properties? If its a matter of the alcohol content evaporating, simply top up with more alcohol (use the denatured industrial stuff, not the medical ones that has emollients added). Of course, if a lot of the alcohol has evaporated after long storage without topping up, then it will turn real gummy, re constituting it would be a beast. Otherwise, I assume that the producers would want consumers to buy fresh batches continuously to keep the sales up. If you have the Zinsser stuff, note that the stuff could eat through the can and leak at the bottom.
First thing I noticed is the variance in colors. This clearly means there's a difference in cut of the shellacs. Secondly the test doesn't represent actual application of shellac. Glass reacts differently from wood, first and foremost, wicks. Second glass only has one side which evaporation can happen.
I'd say recut if needed and if issues are happening it's likely a problem with application or cut versus the shellac itself.
Good video though. I was admittedly cringing when you were testing only the thickest parts of the drops. :) You caught yourself in the end!
I think that you have added to the knowledge base. With out this information good usable shellac might have been erroneously discarded with the thought that it was no longer viable.
Well you can't get 100% alcohol, it absorbs moisture. The purple meths (there is no methyl alc. in it anymore) only really shows it's colour on very light coloured shellacs such as Platina. High purity Isopropyl is a good substitute and it's clear. Flashes off a touch slower but you can certainly French polish with it.
Waxy shellacs certainly keep much longer. In the dry state seedlac and button lac seem to keep forever. If you did your test on mixed 6 month old shellac you might then see a difference. All shellacs go through a process of esterification, which degrades them. Thicker cuts keep longer than thinner cuts.
+vihuelamig Useful info. Thanks!
vihuelamig i
vihuelamig salt can be used to separate the water from alcohol, salt and alcohol do not mix.
It's also the closest way to get close to 100% with out heat.
Then there is the slight risk of salt contamination, which is doubtful since the salt and saltwater will settle down, and you could just decanter the alcohol off.
You have a delightful manner.
I think I've watched all of your videos now on shellac and mixing etc. Can I suggest you search Eddie Castelin on you tube and his excellent videos on "O B Shine juice". I'm not sure if its specifically for wood turners but its super easy to make and really works a treat.... for wood turning at least!
One would think that if shellac liquid has a "shelf life" you might not find it premixed in paint stores, Amazon, etc.
The bottles/cans on the shelf are full with little or no oxygen in them. This is a huge advantage and variable when figuring shelf life. They are also protected from light in the new cans/bottles
@@brandysigmon9066 All true, but pre-mixed does still have a shelf life. The manufacturer's know this. (I've spoken with them). They used to print it on the cans, but stopped because people were not buying the older stuff. Just like you do with milk!
very cool video!
use denatured ethanol tp make you mix
Lol. Just buy high quality ready made shellac. I have used several hundred gallons of shellac and AFAIR I have only ever had one instance of stickiness, which could of been a reaction. I have used shellac that is several years old on hundreds of occasions with no issue.
I am guessing the flakes are more easily oxidised and that non industrial alcohol contains more water.
I have never discarded any old shellac due to age.
Thanks
Why don't you just drink normal wine like the rest of us ;)
I use methylated spirits but mine has no color if your meth comes purple i would suggest that you going to have distill your own alcohol especially if you luthiers start drinking some just befor you belt out a tune
And how old were your flakes before you got them from your supplier? No one knows for sure. This test is ridiculous. You have no idea how old Shellac flakes are to begin with. I have used shellac that I mixed in 2007 and 11 years later it still works fine.
the trial and error tests like this that teach us things that can only be passed on from experience ........do not watch layman playing scientist