I feel a little hesitant about using polymerized shellac for its
adhesive qualities.  I did it a couple of times, and it seems to have
worked.  However, I believe that it is desirable for the shellac to
fully harden in all uses, and old shellac will not do so.

For making burnt shellac, I use a thick Pyrex 500ml measuring cup.
They are heat resistant.  The only reason for setting the shellac on
fire is to hurry the process of evaporation of the spirits; leaving a
small amount of shellac exposed to the air for a couple of days will
have the same effect.  I also use wooden kitchen matches, held with a
pair of pliers if necessary.  The flames are nearly invisible, and are
a real hazard.

I often will ignite the shellac on an outside concrete stoop, and wait
a minute or so for the alcohol to burn off.   When the shellac starts
to boil, then it is very near the right consistency; a strong, hard
puff will blow out the flame.  The shellac will be quite hot then, so
it is prudent to wait for it to cool down a bit.  I use cheap acid
brushes from an auto-finishing supply to apply the shellac, because the
plastic fibers are pretty gunked-up afterwards and need to be thrown
out.

I hate to waste shellac, so I only use the minimal amount necessary.  I
hope that shellac does not disappear from the face of the earth; it's a
wonderful natural product.

Mark Ritzenhein