Shellac functions as a versatile wood treatment and coating, and acts as a binding agent in paint and rust treatment. It is commonly used as a primer, basecoat or undercoat prior to painting, a knot and stain sealer and odour blocker, as well as a high-gloss wood varnish, being a key component of the French Polishing process. Shellac is also resistant to ultra-violet light, so does not darken with age, and is both quick drying and cures at relatively low temperatures. Damaged Shellac can simply be touched-up with a fresh coat of Shellac because the new one amalgamates with the existing coat. Brushes can be cleaned using methylated spirits.
As a natural resin, Shellac is compatible with many other finishes. After dissolving in a liquid solution, coloured Shellac can be used as a brush-on stain, while clear or blond Shellac can be applied without affecting the colour of the wood. Shellac applied as a protective topcoat finish provides a barrier against water vapour penetration, protecting wood against moisture damage.
Shellac is a key component of the French polish method of finishing wooden furniture, particularly for antiques. Luthiers use Shellac to French polish stringed instruments, including guitars, violins and pianos, and to help bind the wood fibres. Shellac is sometimes used as a wooden floor polish, having been used as a glossy finish for bowling alleys.