Ron Hock wrote:

Freshly mixed shellac is remarkably durable and very water resistant. I
tested a piece of fir with a couple coats of 2# shellac by covering half
the piece with foil and leaving it outside for the month of February.
Rained most every day and after a month, the shellac showed no signs at
all of any damage. In fact the only change in the piece was the color of
the fir that darkened by being exposed to the light.



My tests have proven the same. One thing I wasn't aware of, as stated
by Jeff Jewitt, is that a shellac finish that has aged looses it's
ability to resist water. The article didn't mention how old the finish
has to be before it begins to degrade.

"Take a board that has been finished with fresh shellac and after it has
fully dried (about a week), pour some water on the finish and let it sit
overnight. When you come back the next morning you will still see the
puddle of water, but the finish will be only slightly marred. Shellacs
ability to withstand water decreases with the age of the film, so don't
try this on old finishes.

An interesting feature of shellac is that it resists water-vapor very
well. In tests done by the United States Forest Products Laboratory on
the moisture-excluding effectiveness of wood finishes (the ability of a
finish to prevent moisture vapor from entering the cellular structure of
the wood – called MEE), shellac rated above polyurethane, alkyd and
phenolic varnish and cellulose-nitrate based lacquers."

See:

http://www.antiquerestorers.com/Arti...ff/shellac.htm

--
Jack Novak
Buffalo, NY - USA

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