Stringed Instrument Sanctuary
Shellac is a resin secreted by the female lac bug, on trees in the forests of India and Thailand. It is processed and sold as dry flakes and dissolved in ethanol to make liquid Shellac, which is used as a brush-on colorant, food glaze and wood finish.
After feeding, the insect secretes a resin, which dries and hardens into a protective covering called lac. The lac is collected, crushed, washed, and dried. After cleaning and heating, it is drawn into thin sheets of finished shellac. The level of refinement, the timing of harvest, and source of the lac, determine the specific color that comes to you, the happy luthier.
Various uses for Shellac:
Spit coat - (1/2# cut) of dewaxed Shellac as a barrier coat between other stains/finishes. This is especially useful when refinishing. Most finishes adhere to it and it adheres at most finishes except wax.
Wood conditioner - a spit coat of shellac can be used to avoid uneven absorption of stains.
Wood Sealer - Shellac can be used to seal the ends of wet timbers, to help regulate moisture loss while drying, and reduce cracking, splitting and warpage. Also, when working woods with a high tannin content, a spit coat of shellac will prevent you from marring your workpiece with black and blue fingerprints.
Top Coat - There is no more beautiful finish for woodwork, than French polish. Shellac is also a good barrier between incompatible finishes. It’s easily repairable (new finish melts into the previous layer). Dewaxed Shellac has the advantage of being able to be used under all top coats. This is unique among wood finishing materials. Dewaxed Shellac also gives you a clearer finish.