For
hundreds of years shellac had been the finish of choice for finishers
of fine furniture until it was largely replaced by lacquer in the 1920’s
and 1930’s. In more recent years, shellac has made a comeback
as woodworkers and finishers have rediscovered the advantages of shellac
finishes.
Shellac is an easy to use, natural finish. It has no strong odor; superior
adhesion (shellac is the original super glue), and hardness. It is quick
drying, and non-toxic in its cured state.
Shellac is excellent as a sealer. It can seal in pine knots, contaminants
like silicone, and odors from smoke damage. You can get a good looking
shellac finish, whether you brush or spray or pad it on with French
polishing.
Shellac, like other finishes also has its disadvantages. It is less
heat resistant and moisture resistant than other finishes. You may find
that it can also scratch easily. Shellac finishes will be harmed by
products containing alcohol and ammonia. So it is best for you to avoid
using common household cleaning products on shellac finishes.
Dissolving Flake Shellac
Dry shellac flakes are dissolved in denatured alcohol or Behlen
Bekhol, a proprietary blend of alcohols. The ratio of
shellac to denatured alcohol is what is called the “cut.”
Thus, 2 pounds of shellac dissolved in 1 gallon of alcohol is a 2 lb.
cut. 1 pound of shellac into 1 gallon of alcohol is a 1 lb. cut. You
can do the math for smaller amount. (For example 1⁄4 pound of
shellac dissolved in 1 pint of alcohol is a 2 lb. cut.)
Your Helpful Tips for Dry Shellac
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It is best to dissolve shellac in clear glass
jars with lids, such as old mayonnaise jars. As shellac is acidic,
it can react with metal cans and turn black.
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Dissolved shellac starts to breakdown immediately.
It is best to only dissolve enough dry shellac to complete your
project. Liquid shellac you have dissolved has a useful shelf
life of 4-6 months.
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Store dry shellac flakes in a cool dry place,
for example, a refrigerator.
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To test liquid shellac, pour a small amount onto
a hard surface like a glass plate. Turn the plate on its side
and let the shellac run down. This will create a thin coat of
shellac which should dry to the touch in 15 minutes. If it is
still tacky after 15 minutes, you should discard it and make a
fresh batch.
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Allowing waxy shellacs like seedlac and orange
shellac to stand unshaken will allow the wax to settle at the
bottom of the jar. The wax will look cloudy settled on the bottom.
You can then pour off or siphon the virtually wax-free shellac
that has collected on top.
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