I had heard a story of a gilder, who had labored many hours
painstakingly preparing and water gilding the frame, burnishing the gold to a
brilliant mirror finish. To preserve the finish, the gilder coated the frame
with a commercial brand of shellac. The beautiful finish was irreparably
dulled.
Perhaps the frame shouldn’t have shellacked in the first
place. But, the gilder learned another lesson. If you must use shellac, don’t
use shellac in a can. Instead, make your own using dewaxed shellac flakes and alcohol
or ethanol.
In traditional water gilding, shellac is typically used to
seal wood, before layers of gesso and bole are applied. Of course, it has other
uses. If you are going to tone a gilded piece, you can shellac the surface
first and then apply a wash of paint. This is what I did when I toned a carving
with casein paint, described in my story Toning Gilded
Surfaces with Milk Paint. The frame in
the picture below was toned with shellac, to which colorant was added. You can
also tone shellac with an alcohol soluble aniline dye.
While shellac is unsuitable for outdoor applications, some
sign makers have used it for glass applications. As the saying goes, shellac
sticks to anything and anything sticks to shellac. In shading an area before reverse glass
gilding, coating the surface with shellac prior to airbrushing, may be the only
way that the finely misted paint will adhere to the surface. After spraying the
shading, you can then water gild the surface and then back up the gold with
paint and varnish.
In
traditional water gilding, shellac is used to seal wood, before applying gesso
and bole. If you are interested in water gilding, I highly recommend taking the
Society of Gilders course, taught by master gilder, Jill London (www.londongild.com).
Shellac comes in a variety of shades: super blond, blond, orange and garnet. Shellac is also tintable with aniline
dyes. A good source for dewaxed shellac
flakes and ethanol is www.toolsforworkingwood.com.
When you are making dewaxed shellac from dry flakes, do not
mix up too much more than you are going to use.
The reason is that the dewaxed variety doesn’t last too long. Some people think that heat accelerates the
aging of shellac. While heat may contribute to aging, it isn’t the main
culprit. It’s oxygen that causes shellac to go bad. That doesn’t mean that
keeping your shellac flakes or mixed shellac in a cool spot, such as your
refrigerator, is a bad idea. It fact, the practice can extend the life of the
product.
Exposed to oxygen, the flakes will begin to harden on the
outside forming a thin outer coating.
When this happens, it may be impossible for the flakes to dissolve.
Storing the flakes in plastic bags or plastic jars may help slow the hardening
process. But over time, and I am talking about years, oxygen will permeate the
plastic and harden the flakes.
In making dewaxed shellac, you will need the
following equipment and supplies:
- · Shellac flakes
- · Denatured alcohol or ethanol
- · Digital scale
- · Blender
- · Glass jars
- · Paper towels (for cleanup)
- · Latex gloves
- · Paint filter
In
making shellac from flakes, carefully measure the ingredients. The general rule
of thumb for measuring solids and liquids is:
- · Measure dry ingredients by weight.
- · Measure liquid ingredients by volume.
For accurate measuring, a digital scale is
indispensable and very affordable. You can buy a good scale for about $20 to
$30. In weighing the flakes, first place
the container that you are using on the scale and then zero it out. Then add the desired amount. The ratio of
shellac flakes to alcohol will vary depending on the cut of the mix. A 1-pound cut means that 1 pound of shellac
flakes is mixed with 1 gallon of alcohol.
To make a 2-pound cut, the ratio would be 2 parts of the flakes to 1
part alcohol. For a 3-pound cut the ratio is 3:1. 4-pound cut is mixed at a
ratio of 4:1.
Measure
your shellac flakes by weight, not by volume. For precise measurements, invest
in a digital scale.
After weighing the flakes you should break
them up. A blender is great for
pulverizing the flakes. (Just don’t let your wife know what you are doing with
her kitchen appliances.) Busting up the
flakes is critical so that you can break through the oxidized skin that may
have formed on the outside of the flake. If you don’t break up the flakes, the
shellac may not dissolve properly. Store any of your unused flakes in a glass
jar. Plastic containers are not as good a glass, because plastic can breathe
allowing the oxygen to pass through.
Pulverizing the flakes in a blender turns
them into granules which will dissolve within hours. Otherwise, it could take
anywhere from one to three days for shellac flakes to dissolve thoroughly,
depending on how old the flakes are.
Measure the alcohol using a measuring cup.
Then, after pouring the alcohol into a glass jar add the pulverized flakes.
Shellac will dissolve in denatured alcohol, isopropyl alcohol or ethanol. The
problem with denatured alcohol is that there is no telling what types of
chemicals are used to make the alcohol undrinkable. Tools for Working Wood
sells shellac solvent, which is denatured ethanol. It’s great for dissolving
the flakes, but it is expensive.
After combining the
ingredients use a clean paint stir stick to mix the ingredients. Screw on the
lid so that it is secure. Then shake up the mixture. This agitation will break through any outer coating,
aiding the alcohol to dissolve the flakes. Until the shellac thoroughly dissolves, you will need to periodically
give it a shake. Shaking mixing things up, as well as preventing the solids
that settle at the bottom of the jar from congealing.
Once the shellac dissolves you need to filter
the mixture using a paint filter to remove any particles. The last step before using the shellac is to
label the jar. The label should
indicate:
·
The
color of the shellac, such as blonde, orange or garnet
·
The
type of cut, such as 1# cut
·
The
date the shellac was mixed
The date is very important, because as soon
as dewaxed shellac flakes are mixed up, the clock starts ticking. The most time you have is about a six month
shelf life. After that you should toss the old shellac and mix up a new
batch.
Store
any of your shellac flakes and mixed shellac in a cool, dark spot, such as your
refrigerator. Be sure to label your containers. Indicate the date that you
mixed up your shellac. Discard any mixtures after six months.
Because the shelf life is affected by temperature,
you should store dry shellac flakes and shellac mixtures in glass jars in the
refrigerator. Old shellac will not dry properly. One way to tell if the mixture is past its
shelf life is to put a drop on a piece of glass. After an hour, press your thumbnail into the
drop. If you leave an impression in the
drop, it indicates that the shellac will not harden properly. There’s nothing that you can do about it.
It’s just bad shellac, which needs to be discarded.
Brushing on shellac
with a soft natural hair brush is preferred method of application. If you use a brush, the best choice would be a soft natural
hair brush. This brush should be
dedicated for shellac only. Before using the brush, soak it in alcohol all the
way to the ferrule, then wring out the excess alcohol.
The challenge in working with shellac is that it dries
extremely fast. That means that you will have to work fast too, if you are
using a tinted shellac to tone an object.
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Hingst began his career 42 years ago in the graphic arts field creating and producing advertising and promotional materials for a large test equipment manufacturer. Working for offset printers, large format screen printers, vinyl film manufacturers, and application tape companies, his experience included estimating, production planning, purchasing and production art, as well as sales and marketing. In his capacity as a salesman, Hingst was recognized with numerous sales achievement awards.
Drawing on his experience in production and as graphics installation subcontractor, Hingst provided the industry with practical advice, publishing more than 150 articles for publications, such as Signs Canada, SignCraft, Signs of the Times, Screen Printing, Sign and Digital Graphics and Sign Builder Illustrated. He also posted more than 325 stories on his blog (hingstssignpost.blogspot.com). In 2007 Hingst’s book, Vinyl Sign Techniques, was published.
© 2015 Jim Hingst
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