Dissolving Shellac Flakes

[Willyou]

I had some Garnet shellac flakes that I dissolved into a 1# cut. After almost a week (shaking it once and a while), there were still some small gelatinous undissolved chunks. I assume that this is normal. I filtered everything and applied several coats. All seems OK. Am I missing anything?

[cputnam]

How old are the flakes and how have they been stored?

[JR1]

Nope that's normal. there is always at least a small amount of shellac which does not dissolve. Pure ethanol dissolves more shellac per volume than DNA besides being less toxic. For seed shellac the dross¹ can amount to ~15 to20%. I've never been able to determine the amount of wax in button shellac.

¹ The dross is vegetable matter and possibly a lac bug or part there of.

[Willyou]

The flakes are kind of old (not sure how old) but, otherwise, the solution seems to work Ok. So, that's kinda what I thought. Thanks for the confirmation.

[fredhargis]

Yeah, that's pretty much the way it works. It might help if you sit the jar with the DNA and flakes in a pan of hot water, heat increases the amount dissolved and speeds up the process a little, but you will still have some undissolved matter to filter out.

[LongLook]

I grind shellac flakes in an old coffee grinder before adding the solvent. Speeds up the process but there is always residue that doesn't dissolve.

[cputnam]

I store my flakes in a doubled ZipLoc bag set and put in the garage fridge out of the way. Short of vacuum sealing I think that is about as good as can be done.

Maybe some other folks will chime in about flake storage?

[fredhargis]

I do the same (fridge). They will keep a very, very long time that way. It also helps with oil based varnish that's been opened, and while I'm not sure it helps I keep the dissolved shellac (in canning jars) in there as well.

[mignal]

Garnet comes in two basic varieties, waxed and dewaxed. The dewaxed will have a much shorter shelf life than the waxy stuff. All Shellac (even dry) goes through a process called esterification, which basically means that it polymerises and becomes impervious to it's solvent, alcohol. The blonde dewaxed has a relatively short shelf life. The cruder forms, such as Seedlac can last decades. I have some Seedlac going back to the very early '90's that still readily dissolves in alcohol. On the other hand I've had dewaxed blonde flakes go off in a matter of 4 or 5 years.
Buitton Shellac should be around 5% wax content but no doubt it varies dependent on what crop and the type of Seedlac it was made from. The processors can increase or decrease the wax content of dry shellac according to instructions of the buyers. Unfortunately you have to be a very big buyer to have that amount of influence. Of course we can add or remove wax once we dissolve our own flakes.
Waxy Shellac has greater abrasion resistance, which seems somewhat counterintuative.