Thread: Solvent for Shellac?
10th Sep 2011, 11:03 PM #1
Solvent for Shellac?
A quick question. A while ago I bought a bottle of low moisture content solvent to make up my shellac with. I'd had problems using commercial metho and thought it may have been due to the fact it can contain up to 20% water. It turned out that the quality of the finish was much better with this solvent.
The thing is, I can't remember what it was called and have lost the bottle somewhere. I have a friend with the same problem who wants some. Can anyone give me a pointer?
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11th Sep 2011, 10:43 AM #2
Answered my own question! "Redistilled ethanol" or "ethanol 95%", I knew I had it somewhere.
21st Sep 2011, 07:38 AM #3
100% IMS (Industrial Methylated Spirits) also called Ethanol
Both should be available from any GOOD paint shop many Mitre 10 shops carry it or used to. Mostly sold in 4 litre bottles but occasionally in 1 litres.
If it isn't marked Industrial Methylated Spirits then it can legally have up to 42% water in it as Metho must be overproof which means it must be able to burn and it will burn with that much water in it. Not worth spit for use with shellac.
To test if Meths has water in it add a little turpentine to the bottle and shake. If it goes a slight milky colour it's got water,if it stays clear... No water.
21st Sep 2011, 08:43 AM #4
Does it really make that much difference?
I chased around town to find some industrial metho 95% for use at home & it works great but down at the community shed we just use good ole Diggers metho straight off the woolies shelf. The diggers brand was half the price of the 95% i bought & it works exactly the same.
And yet the only time i have ever had blooming in my shellac finish was at home where i used the 95% - i put this down to the very high humidity in my shed at this time of the year.
21st Sep 2011, 10:19 AM #5
Probably was the humidity.
It does make a difference as I said above if it's hald full of water you wouldn't even get the shellac to dissolve and unless it's marked Industrial Methylated Spirits it could be. If marked IMS it has to stick to the standards. 100% is the best 95% will be fine and unmarked could be dodgy. The unmarked is up to the manufacturer. If your not sure about the water content do the turpentine test and if it ain't clear then it's a pretty safe bet your shellac will bloom if it dissolves in the first place.
Oils ain't oils.
21st Sep 2011, 08:24 PM #6
Thanks for that. The Turpentine test is defiantly 1 i want to remember. Shellac is a favorite finish of mine.
When u say "add a little turpentine to the bottle and shake" u mean a small test sample of the metho or do u mean the whole metho bottle?
Is the metho effected by having a little bit of turps in it?
& do u mean mineral turpentine or gum turpentine?
25th Sep 2011, 07:46 AM #7
Probably best to take a little out of the bottle and try it. Mineral turpentine does the job. Best to pour the meths into a clean bottle of some sort snf then add the turps and shake. you aly need a small amount of turps but under normas circumstances and with clean waterless meths you can add as much turps as you like and the mix will stay clear.
I test most of our 100% IMS this way because we have had wrongly marked drums in the past and that's a disaster for us because even the 5% of water in 95% IMS will stop waxes from properly combining when we make Shellawax costing thousands of dollars, it can also make a difference to the quality of our premixed shellac. Most manufacturers of premixed shellac use 95% IMS we only ever use 100%. Costa a little extra but I reckon it makes for a superior product.
It is not uncommon for 95% to have up to 10% water in it so buy quality product and not cheap unknown stuff. Although MSDS's may say 95% alcohol they often say >4% or >5% water meaning greater than 5%. Should say 5%. Oh yeah, and the denaturant should be around 0.03%.
If in doubt find the MSDS for the product you're going to buy and check out the water quantity and the denaturant. I have seen some with as much as 10% Methanol and that's not really the best of things to be playing with.
25th Sep 2011, 09:20 AM #8
Thanks so much for that info Neil, i'm going to make it a standard practice in future
28th Sep 2011, 01:52 AM #9
I've not got Neil's expertise but I can tell you it makes a substantial difference. I learned the hard way that the metho off the standard hardware shelf (diggers/walkabout etc) can have more than a third water in it. It also has other additives to make it less "palletable" (read more poisonous): commonly methanol, acetone and propanol.
One of the big pluses of using shellac-based finishes as opposed to resin-based or acrylic varnishes in my book is that I can avoid exposing myself to petrochemicals. So avoiding the nice little cocktail in shop metho is also important to me.
If (and this is a big if) you can get the shellac flakes (or buttons if that's your thing) to dissolve in metho you'll often end up with a patchy inconsistent finish.
I don't keep a big supply of the redistilled stuff either; because ethanol is hygroscopic. It absorbs water from the surrounding atmosphere and ends up less effective over time. Even with the lid screwed tight. I just buy enough for the jobs I have at hand.
28th Sep 2011, 11:37 PM #10
Not sure if this will work woth metho (IMS or otherwise) as I don't know how the chemical would react with the seals but I have heard of people decanting things that are hydroscopic into empty (and cleaned) cask wine bladders, then expelling the air and only using the small amounts they need through the tap. It's meant to reduce the exposure of the product to air and it's moisture.
29th Sep 2011, 10:12 AM #11.
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For those interested in means of storing rectified spirit (~95% ethanol), keeping it dry or making it dryer you might be interested in this report from researchers at Purdue Uni who have found that tapioca pearls are very effective in drying ethanol, better than molecular sieves and easier to obtain. I don't see any problems with storing your IMS over it, tapioca starch is insoluble in alcohol. Worth further investigation as an application in French polishing, perhaps even storing shellac solution over the granules.
29th Sep 2011, 01:38 PM #12
You can buy commercial desiccant for the same purpose, but I like the thriftiness of using tapioca..
I know you believe you understand what you think I wrote, but I'm not sure you realize that what you just read is not what I meant.
2nd Oct 2011, 09:27 AM #13perhaps even storing shellac solution over the granules
2nd Oct 2011, 11:43 AM #14
Maybe the tapioca could be in a little mesh bag of some sort? If its not going to disolve its not going anywhere. I kinda like low tech solutions. I could make little musli tapioca pouches.anne-maria.
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2nd Oct 2011, 11:46 AM #15.
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