Varnish is a transparent, hard, protective finish or film primarily used in wood finishing but also for other materials. Varnish is traditionally a combination of a drying oil, a resin, and a solvent.
Most resin or "gum" varnishes are made of a natural substance dissolved in a solvent. The two main types of natural varnishes are spirit varnish (which uses alcohol as a solvent) and turpentine or petroleum-based varnish. Some resins are soluble in both alcohol and turpentine.
Shellac is a very widely used single component resin varnish that is is dissolved in alcohol. It is not used outdoors or where it will touch water several times, such as around a sink or bathtub. insects in South Asia make it.