Thursday, October 15, 2009

Shellac Attack

The lac resin has been known since 1500 BC, and it is the only resin of animal origin. The lac (Tachardia lacca) are tiny insects that swarm and live off of host trees in India. They suck sap into the their bodies and excrete a resinous substance through their pores to form a crust on the twigs and branches. The crude lac (or sticklac) is scraped off the trees then dried, crushed, sifted and sorted. Traditionally this process was done by hand, but now can done by machine. When the lac is done being processed it is in flake form, as pictured above. To make shellac, the flakes are dissolved in alcohol. Today you can still buy shellac flakes at specialty store or buy premade shellac at any hardware store.

Shellac (handmade) is all natural and has been utilised for the manufacturing of many products including paint and varnish, a glaze for fruit, coffee beans and nuts, a coating for tablets, as a leather dressing, a sealing wax, as a printing ink, in cosmetics, in confections, as food coloring and polishes. Since shellac has been around for so long, it is found in many historic structures and furniture. Shellac is also best for inside surfaces, and is used in many fine finishing techniques, including french polish.

To test to see if a surface is in fact shellac, dab a small portion of it with denatured alcohol, which is the solvent for shellac. If the surface becomes tacky, it is most probably shellac.

More Graining

Above are the pocket doors that we learned the graining technique on at the Annie B. House. We scraped and sanded off as much paint as we could before applying an oil based white primer.
In the background, you can see we have applied an oil based ground to the door. This can be bought at the store and used as is, or you can fine tune using dry pigment and artist oils. We added paint thinner to ours to increase the amount of time we could work with it. It is important to make this surface look homogeneous because it will be seen through the glaze, which is the next step. In the foreground, our teacher Peter is testing the glaze. The glaze too can be bought at the paint store, it also can be fine tuned and thinned to give more time to play. On these doors we are trying to replicate redwood, so we have a warm reddish brown as the ground. The glaze is transparent, but darker. Two colors important to perfecting a wood color are burnt umber and burnt sienna.

Here, Peter is applying the glaze. It is best to do a smaller section at one time, so you can work on your grain technique in one place and not worry about the glaze drying somewhere else. Peter suggests paying attention to the construction of the door, so graining is done in the correct directions.

Peter is using steel wool to apply a texture to the glaze. There are many different tools one can use for an array of effects. We used were steel and plastic combs of different sizes and shapes. Also in the tool bag were rubber rollers with wood textures and various brushes. Brushes can be used to lightly go over work in order to soften the grain's look.

Here are the pockets doors partially grained with different techniques and done by the students in the interior material class. We left some undone for comparison.