I’ve used dewaxed shellac for years–sometimes putting a top coat of poly u sometimes not.
2 years ago I decided to take advantage of the lower prices for a larger quantity. I mixed a batch in my usual way and was left with many undisolved clumps. Thought it might have been a fluke and tried it again–same problem.
I thought the flakes had an indefinite shelf life.
What, if anything, can I do?
el viejo
Replies
Orange vs dewaxed
I believe that orange shellac will last forever if kept dry, but dewaxed shellac is different. I don't know why though. I read that somewhere, but by my logic if you grind up the clumped shellac flakes, it should be fine. But don't take my word for it.
Possible shellac solution
I experienced the same problem. Thinking also that my shellac flakes had reached the end of life. An experienced worker at my local Woodcraft store pointed me to the fact that it may be a problem with the alcohol. I purchased new flakes and solvent anyway to make sure the project came off.
The guy was spot on, new solvent and my old flakes dissolved as expected. There are differences in the various grades of alcohol.
shelf life of shellac flakes
I'll bet you're right. Alcohol will, of course, be diluted with water or moisture and would surely work less well. My can of alcohol is at least a year old and could have been "moisturized." Thanks!
hey old man,
recently a buddy and i purchased two bags of, made in germany, unwaxed shellac. i am not a finishing expert. my friend is. he mixed his usual 2# cut and had the exact problem you have. we drove to the vendor and he said we should add more alcohol. we did, to no effect. i do not know the name of the reference book ,(i could get it if you wish), my friend looked into, but the author states the shellac has come into contact with ambient moisture when it will not dissolve completely. a trip back to the vendor, with ref. book in tow, and we were given no further arguement. we got store credit and we're waiting for a fresh batch to come in.
eef
Moisture through Alcohol?
Eef,
You mention adding more alcohol, but not different alcohol. Could it have been that the moisture came from the 'impure,' old alcohol, rather than the shellac flakes themselves?
--jonnieboy
jb,
quoting a book and not providing its title is probably just plain wrong. my friend, the finisher, read to me that if the container in which the flakes are kept is compromised, moisture can and will enter and one will be left with flakes that will not dissolve in alcohol. the plastic bags, in which the flakes came, were pretty wrinkled and crinkled. my buddy used clean, fresh denatured stuff. after what others have said, moisture and shellac flakes should be kept apart.
eef
Moisture is Death
Moisture is death to shellac flakes. When exposed to moisture,as in water vapor from humidity or liquid water, a chemical reaction takes place that makes the shellac un-desolvable. It doesn't matter what kind of alcohol you use, it just won't desolve.
My wife brought me a kilogram of shellac flakes she had left over from a project in her home country. The flakes had sat in a plasticv bag, in a shed, for several years. The humidity would range from 70% to 100% with long periods of 90+% not unusual.
I tried to use some of it. Ground it up in a coffee mill, used brand new alcohol, cussed it, begged it, cajoled it. It would not desolve.
So I changed tactics. I started putting alcohol into myself. Lo and behold, in about an hour I didn't care about that #%*& shellac...
Put your alcohol and shellac in a glass or plastic sealed jar then let it stand in hot water (I usually heat the water to around 150 degrees.) Take it out of the water bath and shake it from time to time. You might have to heat some more water if it cools and the flakes haven't dissolved. This has always worked for me.
This seems to happen to me when the weather gets cool.
I've found that regular agitation is required to get the flakes to dissolve properly. Grinding them up first works well. I have flakes that are 10 years old that I used to make a fresh batch of shellac just last week. They are kept dry in a sealed container. They all dissolved just fine.
I use my wife's vacuum sealer to vacuum seal my remaining flakes - seems to work well. I had some flakes well over 2 years old that were like new.
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