With just shellac I have found the finish to gum up and become uneven.
That
is, if you try to work the finish for more than 20 seconds. Try 2 parts
shellac to 1 part mineral oil..... It's basically motorized french
polish.
The oil gravitates to the top and lubricates. The shellac migrates to the
bottom. You can keep working it while the shellac sets up. Just wipe off
the
oil after the shellac has hardened up.

That's something worth trying, but one thing does immediately come to
mind- how old is your shellac? I did find that when it was very
fresh, it works great, but the can that I have had for a year or two
now no longer will set up properly at all, and becomes gummy and
uneven just as you've described.


It's not an old shellac issue. The gummines comes bcause the finish dries
too fast ... not to slow. IME, when I put just shellac on a spinning turing,
the finish starts to cure in about 15 seconds. Inside of a minute, it's
thick and sticky. This stickyness causes more friction, and consequently
heat, which causes the finish to firm up even faster.

The problem is with the "sticky" property. I find that it tends to clump up
the shellac, the opposite of having it flow out. The result is thick and
thin bands of finish around the axis of rotation. It's basically a violation
of the "keep a wet edge" rule of shellac application. But keeping a wet edge
on a spining object tends to spray shellac everywhere (my low speed ain't
that low).

The solution is to add mineral oil to lubricate, just like a french polish.

-Steve



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