These must be suited to the description of gum they are to dissolve.

Boiling Linseed Oil (and sometimes other oils, such as rosemary) is used to dissolve amber, gum anime, or copal.

Turpentine for mastic, dammar, and common resin.

Methylated Spirits of Wine 1 for lac and sandarach.

Wood Naphtha is frequently used for cheap varnishes. "It dissolves the resins more readily than ordinary spirits of wine, but the varnish is less brilliant, and the smell of the naphtha is very offensive. It is therefore never employed for the best work.2

Driers are generally added to varnish in the form of Litharge, Sugar of Lead, or White Copperas.

The sugar of lead not only hardens but combines with the varnish.

A large proportion of driers injures the durability of the varnish, though it causes it to dry more quickly.