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Shellac That Won't Dissolve
Question
Forum Responses
From the original questioner: Shellac is a natural soluble substance. It does not die. There are no solvents in the shellac at this point. From contributor B: What are "methylated spirits"? From contributor S: Methylated spirits is denatured alcohol. I am not a shellac chemical analyst, but studies have proven that shellac does not have a guaranteed shelf life for solubility. Shellac is thermoplastic but slowly becomes thermosetting. Lac, on aging, becomes slowly insoluble in alcohol. After about two years in storage in India, it is no longer soluble in cold alcohol. Upon boiling with alcohol, it becomes soluble or is peptized into colloidal solution. I would not recommend you try this at home. There is a point when shellac gum subjected to heat will "pass over" or polymerize from a plastic, soluble state to a tough, rubbery, insoluble form. I would try grinding it finely in a blender and then try to dissolve in a different brand new can of methylated spirits. If it doesn't dissolve, let it go.
From contributor T: Have you previously dissolved shellac in alcohol successfully? How long did you soak the shellac (and shake or stir it) before deciding it doesn't dissolve? There are previous posts in this forum discussing the merits of types and proof of alcohol and you may want to consider those factors in this endeavor. From the original questioner: The microwaving was on shellac flakes only, no solvent. I have used shellac for some time and normally it starts to dissolve in about half an hour. The mixes I am trying are in clean jars and are still in the sealed jar with solvents but will not dissolve. "I would try grinding it finely in a blender and then try to dissolve in a different brand new can of methylated spirits." I will go with this now and see if I get any difference. Thanks. I suppose boiling in alcohol could be tried. Staying under the evaporation state of alcohol and on an electric source of heat ought to be safe enough, for a small try anyway.
From contributor S: Boiling shellac is a specific test used to determine a quantitative quality of shellac. It is a lab test, performed only for the scientific purpose of determining how it responds to such. Shellac is not meant to be made up by boiling it and I believe doing so would further its degradation. Shellac that is still of good quality will dissolve in cold alcohol. If it doesn't, it is no longer useful. That said, shellac can take days to fully dissolve in cold alcohol. You can speed up the process by placing the closed container in an ultrasonic bath or a warm water bath or by constant mechanical stirring or frequent shaking of the bottle. Shellac thrown into a jar with solvents will initially become a molten "block" at the bottom of the container. If it is not frequently shaken I have no idea how long it would take for the shellac to fully go into solution. Perhaps you need to have more patience and put it somewhere that you will pass by it often. Shake it well every time you pass by. If it does not dissolve completely using that means within a few days, then it is a good indication that the shellac itself is no longer of good quality. Not something you would want to use. Would you like to add information to this article? Interested in writing or submitting an article? Have a question about this article? Have you reviewed the related Knowledge Base areas below? 
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