A violin varnish is never just one substance — it is a carefully balanced blend of ingredients, each with its own role to play.
Resins form the backbone of the varnish. They create a smooth, glossy film that gives hardness and shine. Makers have long relied on resins such as mastic, dammar, sandarac, amber, or colophony.
Oils, used in oil varnishes, act as the binding agent. They give the varnish flexibility, allowing it to move with the wood. Cooked linseed oil is among the most common choices.
Solvents make the mixture workable. They dissolve resins and oils so that the varnish can be brushed onto the instrument. Alcohol (ethanol) is used for spirit varnishes, while turpentine oil is common in oil varnishes.
Finally, plasticizers keep the varnish from becoming brittle. Traditional makers often add soft balsams such as Venetian turpentine for this purpose.