Rejuvenate Old Shellac?

[Derek Arita]

I've got a can of shellac that's about 5-10 years old. Although it looks fine, it's been brought to my attention that shellac can get old in the can and not cure properly once applied. Is there a way to rejuvenate that old shellac?

[Prashun Patel]

If shellac absorbs too much water, it may not dry properly. Shellac doesn't cure.

Test it by putting some on scrap. If it dries within 30 minutes and sands to a white powder, it's fine.

[Derek Arita]

Let me explain...I finished some boxes with the shellac. After a few days, I stacked them. Later, when I went to get the boxes, they kind of stuck to one another, but there were no marks left. Not bad, but I could still tell the finish was not fully hardened. I posted and was told that quite possibly the shellac was old.

[Mel Fulks]

Never heard of any way to bring it back. The flakes have been too long in the solvent ....and are now "insolvent". Broke!
Its best to buy the flakes and and alcohol and make your own batch. Some of the denatured alcohol sold in hardware
stores doesn't disolve the flakes well ,but works okay for thinning it and cleaning the brush. You can buy good alcohol on
line that is made for that purpose.

[Derek Arita]

Ok, thanks. It's kinda weird to me that it would get old. I figured that might be the case, so I purchased a smaller amount for another project and will likely do the same from now on.

[Rob Luter]

I had this happen too. I bought some Shellac flakes and mix it it as needed 1/2 pint at a time. No waste. Boy does it dry fast too!

[Andrew Seemann]

Over time the shellac molecules change in the alcohol and eventually they change to the point where they do not dry correctly. The length of time depends on many variables, but I suspect temperature is a main one. The process isn't reversible.

In-the-can shellac is fine as long as it gets used fast enough. Myself I go through it quickly enough to buy it by the quart can or two.