Shellac composition


Hello all. Does anyone have information about dewaxed shellac composition. I usualy bought shellac from a hardware store and I am not sure that its the best shellac to use on finishing, hardware store could not provide me any specifications. So while looking at chemistry supplies providers if found this shellac ************************** Alcohol Insoluble 0.72% Color Lovibond 12 Acid Value 65 Fusion Range 73C Iodine Value 14.5 Humidity 1.33% in Alcohol Wax 3.42% Ashes 0.145% Rosins NIL Colofona NIL **************************** It says 3.42% wax, I wonder if dewaxed means 100% wax free or not ?
Also regarding shellac preparation, I use 15gr shellac + 120 gr alcohol for 1 pund cut and 30 gr shellac + 120 gr alcohol for 2 pound cut. So I tried this time to use hot water to heat up the flasks with shellac, stirr every now and then, for 2 days but shellac just wont dissolve, a large amount of flakes just wont dissolve totally and just sit there. In the beggining the solution is like a suspension but after a couple of days it cleared up and the undissolved matter kind of 'vulcanised', I mean that it formed nuggets and precipitated on the bottom. For one I am happy that the solution is nice and transparent but otoh I wish that all of it dissolved. I guess the shellac from hardware store I am buying is not top notch quality. I guess Id have to get some dewaxed from shellac.net, happens that I am in Mexico and its kind of hard to get something good quality with full specifications on it.
Konstantin.
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I don't know about the dewaxed or not, but I use the premixed Bull's Eye shellac available from home depot. It is already mixed in a factory, so they can do it much more accurately than I could ever. It is dewaxed, and can be thinned with alcohol if necessary. It may be hard to find in Mexico, but I bet that you can get it by mail. My guess that the hardware store shellac might have used to be passable, but it has probably sat there much beyond its shelf life, which is usually only about 6 months.
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woodworker88 says...

Only the Bullseye Seal Coat is dewaxed, but it is found in more stores than the regular shellac, because it isn't advertised as being shellac. The hoi polloi wouldn't buy it if they didn't think it was a new and mysterious concoction. It's a good bargain at about $8 a quart for a 2# cut from a discount box store. The regular Bullseye blonde and orange shellac is definitely NOT dewaxed.
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Zinsser says their spray can is also dewaxed as wax plugs the nozzle. www.homeateadfinishing.com has the history of shellac as an article that makes an interesting read albeit fairly long.

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nospambob says...

Forgot about that. But it's kind of expensive.
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eliminate the typo and try:
www.homesteadfinishing.com
-- Learn from the mistakes of others. Trust me, you cant live long enough to make them all yourself. Ive tried!!

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snipped-for-privacy@gmail.com says...

I assume you aren't buying dewaxed shellac, and if that is the case, then the wax will always be suspended in the mixture and if it sits for a few days, it will settle to the bottom of the jar. My guess is you are seeing mostly wax falling out of the solution. Also bear in mind that since shellac is a natural product produced by insects, it will have impurities in it and you are supposed to strain it before using it. What you are seeing sounds normal to me and if you separate the clear solution from the precipitate on the bottom, you will have made your own dewaxed shellac. Also beware of the quality of your alcohol as well as the shellac. If the alcohol has much water in it, it won't dissolve the shellac very well. Alcohol would be a good thing to buy from a chemical supply house, because the quality should be very high. Keep your alcohol closed tightly at all times, because it will draw moisture from the air. If you can find Zinsser Seal Coat in Mexico, it is a dewaxed shellac already made for you in a 2 pound cut. It is very common in the US.
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I think the right alcohol is "anhydrous" ... means there is no h2o in it. Sold and explained by Hock tools.
What is the problem with waxed shellac anyway? Why the preferences for the dewaxed variety?
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Alex - newbie_neander in woodworking
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AAvK wrote:

If shellac is used as a barrier coat wax may cause adhesion problems with the top coat.
Most of the problems people often associate with a shellac finish are caused by the use of shellac containing wax. For instance, I've experimented with shellac by taking a scrap piece of black walnut finished with dewaxed shellac. I poured a puddle of water on the finished piece, set a glass in the puddle and left it sit over night. the water did not harm the finish and there was no white ring. Trying the same thing with a scrap finished with shellac containing wax didn't fare too well.
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Jack Novak
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AAvK says...

In addition to what Jack said, dewaxed shellac gives a clearer finish. I'd be curious to hear if anybody knows a situation in which leaving the wax in is preferable. Maybe there is, but AFAIK, the only disadvantage of dewaxed is the cost, or time if we do it ourselves.
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Yes and no. Truth to tell, the stuff they put in to get the last 5% water out is about the worst (for you) part of the mix. Why 5%? Look up azeotrope.
Then there's that other truth, that open jars and jars with a lot of air allow the alcohol to gain atmospheric water. It's not a big deal up to perhaps 10%.

As others have mentioned - it behaves like wax in its rejection of finishes and traps water underneath to give a brighter "blush" ring. Not to mention, there are probably some other non-polar organics extracted along with the wax, though they may have helped, rather than hindered by being there.
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Konstantin:
Try http://www.woodfinishingsupplies.com / click on Shellac link. This site has about 2 hours of reading on shellac and the products they sell.
As you said, you purchased shellac from your local hardware store, but since not all shellac is created equal (natural product like wine, beer, etc) I suggest you try another source. Several sites on web sell high quality shellac, and with higher volume sales, products from these site may not have been on store shelf for long time.
Phil
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