BUG SWEAT OR TEARS - A Treatise on Shellac
By Rick Glawson
What do certain popular candies, floor finishes and auto mechanics have in common? Or more to the point, what do they have to do with our trade? In an age where we are always looking for some new high-tech material to make our work easier, or to prevent the inevitable blotch that spoils the perfect job, we have overlooked a most basic material. SHELLAC.
Produced in India by the Laccifer lacca, or lac bug, this material oozes as sweat from their bodies as they feed on sap from several species of local trees. Deposited on limbs and twigs as crust, it is collected, rendered down and shipped world wide for further refining and production into a usable state.
Soluble only in denatured alcohol (denatured meaning a change in it’s nature by adding a poison to ethyl (grain) alcohol to free it from federal taxes), it remains not only reversible, but adheres to most any material or paint. Equally, most any paint adheres to it whether oil or water based. It dries in less than half an hour and with the exception of exterior use, makes a hard, clear elastic top coating. Floor and furniture finishers can attest to this. Auto mechanics use it as a gasket sealer, and house painters use it to block out mildew stains.
Sign painters at and before the turn of the century were also known for their graining and decorating talents. For this reason they also had under their belt a greater range of use and understanding of the materials at hand. Shellac remains today one of the few store shelf items unharmed by technology.
There are two distinct class or grades of the material that we shall call commercial and “mix-it-yourself”. For most uses the “commercial variety is adequate. It has a cloudy appearance in the can because of residual waxes yet becomes clear upon drying. You will find this grade under the BULLS EYE brand name manufactured by the Wm. Zinsser & Co. of Somerset, New Jersey, and is packaged in quarts and spray cans. The higher-grade dewaxed versions (available at gilding suppliers) come in several transparent colors (blonde, lemon, orange or ruby) and come packaged in dry flakes. These you mix yourself, normally two parts alcohol to one part shellac, adjusting as desired. Do your mixing and storing in glass jars and with the commercial grades once opened, store in a glass container or the material left in its metal can will turn dark. Remember all clean up is done with alcohol whether wet or fully hardened.
When blocking out an existing panel, shellac over any red painted graphics or lettering. Acting as a barrier, it will prevent any bleed through of the original red.
Shellac also acts as a moisture barrier and has traditionally been used as a mirror backing. Even with our modern mirror back up paints, it is a safe practice to coat resilvered or new panels with a layer of shellac prior to the cosmetic black one. In this same respect, use shellac to seal any type of carved or sandblasted stone or wood before applying you gold size. This will prevent any moisture within the material from pushing off the gild. It will not only seal the porosity, but by adding a universal tint or dry bronze, you can have any base color you desire. As an example, mix in aluminum powder to undercoat palladium, pale bronze with deep gold, etc. Following this train of thought, the same metallic shellac is excellent for backing matte centers on window work. Drying quickly, it allows you to cosmetically finish up your work without fear of your black breaking through the matte or having to wait for metallic lettering enamel to dry. It will also hide any small holidays or thin spots in the leaf caused either by manufacturing, human error, or aggressive pattern burnishing.
Worthy of note is the ability of a shellacked surface to repel low pressure sandblasting. Reusable stencils made from shellacked Manila paper was once commonplace as well as saturated cotton lace. The latter can be quickly adhered to the glass with asphaltum varnish and lightly blasted for highly decorative effects, but that’s another story. Old timers may remember shellacking paper stencils and ironing them on to a silkscreen frame for printing quickie signs.
A recent practice with antiquated roots adopted in our shop involves spraying a thin coat of Bulls Eye as a fixative on the reverse of hanging glass signs after all shading, outlining, etc. has been done, and before the final background is applied. If you have ever had what you thought was fully cured, painted filigree start to soften and move around under a half marbled surface, you can understand this simple step. Another advantage is when drilling holes after completion (as is our practice); the exiting breakout caused by the drill is kept to a bare minimum. So strong is a shellac film, that if sprayed fairly heavy on one side of clean plate glass before edge scalloping, the fulcrum point of the glass nipper will be shoved clean through the glass without effecting the edge. There is no value in this result other than to illustrate a point.
In our production of period style glass signage, we often set flat backed glass jewels and abalone shell into letter centers and ornaments having burnished gold outlines. As these embellishments are applied last, their openings must be kept open. If a solid color background is required, it’s then no chore to simply fill in around these spaces. When more imaginative backgrounds are desired, so are the necessary steps. After all color shading and line work are applied and dry, spray on a light shellac coating as mentioned before. Now with a brush apply two or three coats of liquid latex frisket (available at art stores) over the areas to be protected, letting each coat dry before the next. This allows unobstructed oil based paint blending, marbling, etc. to be completed. When dry, prick an opening in the frisket with an x-acto knife and with your finger rub off the remaining film. Using a pad of paper towel lightly saturated with alcohol, clean out the shellac residue. It will have become clouded during the masking step but protected the gilding underneath. Without the shellac layer, you will lose at least some of your bright lines during the rubbing out process. Only the shellac, being soluble in alcohol is affected.
Although the commercial grade of shellac is sufficiently clear for the previous techniques, I would advise mixing your own for the following. As earlier stated, the grade of flakes used is dewaxed, giving a distinct clarity. In much of our work where abalone shell and mother of pearl is used, often as building or object backgrounds, the iridescent yet paler varieties leave room for artistic endeavors. This is where glazes come in, and most rich of all is (say it with me) shellac. Well-mixed ruby flakes impart a deep golden yellow color much improved over the cloudiness of transparent screen inks. By adding aniline dye into a blonde mixture, you can achieve any color in the rainbow. The dyes drawback is retaining its color in direct sunlight, but is rewarding for most interior use. A source of the liquid form that’s both user friendly and obtainable is Dr. Ph. Martin’s radiant concentrated water color, found at most art stores. It will quickly intermix with your shellac and straining is unnecessary. You will equally find this glaze appealing either under or surface applied over with gold leaf.
We have also found that by mixing the blonde in a heavy solution, say one to one ratio, a wonderful adhesive for attaching glass jewels is achieved. It takes two to three days for them to completely set but the wait is worth it. One note when mixing fresh shellac, don’t expect the flakes to dissolve overnight. It can take several days with periodic shaking to complete the task, so plan ahead.
The next time you face the above-mentioned situations, give shellac a chance. It deserves it. By the way, if you wondered about the initial reference to certain popular candies, you may now have a clue as to why they don’t melt in your hands.