I'm puzzled. I've always read that shellac has about a 6 month shelf life
and to toss the old stuff after that time. About 18 months ago I made up
some 2# cut of shellac from scratch. After I was done with it, I kept it in
a sealed plastic bottle.
Out of curiosity I took it out this weekend and used it straight from the
bottle on a small test project just to see what happens.
Nothing. It *appears* just fine. Dried quickly and firm. I was able to scuff
sand between coats. Tried brushing and padding - same thing - no problem.
Is there a hidden downside or did I just get lucky?
Not the most earth shattering issue of the day but a curiosity to me none
There are 10 kinds of people - those who understand binary and those who
the old stuff after that time. About 18 months ago I made up some 2# cut of
shellac from scratch. After I was done with it, I kept it in a sealed plastic
Keeping shellac a sealed bottle just keeps the alcohol from
evaporating. Shellac contains organics acids that will, over time,
react with alcohol to form esters. At that point the shellac won't dry
properly. Clearly, the rate of the reaction in your case was slow, but
about six months is the time it normally takes for esterification to
On Mon, 21 Jul 2008 08:25:18 -0700, Bill Leonhardt wrote:
At date of manufacture. But Zinsser puts some sort of preservative in
their shellac that they claim keeps it usable for 3 years. I get nervous
after two and toss it.
BTW, use the Sealcoat, not the stuff with wax in it. Sealcoat is marketed
as sealer, but it's just a two pound cut of dewaxed shellac.
I've been told that the preservative keeps the shellac from ever drying
quite as hard as the non-preserved stuff, but I can't tell any difference.
If that possibility bothers you, mix your own from dewaxed flakes.
I have had goo dluck using shellac that is as old as 4 or 5 years.
I've never had shellac "go bad".
While I understand the chemistry involved with thetheoretical deterioration
of shellac, I've just never experienced it. I use steam distilled alcholohol
to make my shellac, almost always use dewaxed stuff, and store it in sealed
dark bottles at room temperature (my shop is usually fairly cool, and rarely
gets over about 70 degrees F)....
-James (who also happens to be a scientist....)
I've got a couple bottles of shellac that are at least 25 years old. I
use it, but whenever I do I have no trouble with its finish or
drying. These are quart
bottles; perhaps the larger volume/exposed surface ratio helps
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