Resins are available from either natural or synthetic sources. Traditionally, resins were derived from exudations of trees and shrubs. In essence they are oleoresinous saps where the volatile solvent content has been removed. Balsams fall into a class of oleoresins where the volatile compounds are still present. Synthetic resins are built from acrylics or other petro-chemical bases. They offer greater resistance to yellowing, embrittlement or blooming than natural resins.
Resins are supplied in a dry form, either lumps or beads, and need to be dissolved in an appropriate solvent to make fluid. They are very solvent specific for complete solubility. Natural resins should only be dissolved in genuine Distilled Gum Turpentine. Synthetic resins are most successfully dissolved in Artists White Spirit.
Natural resins, in particular damar are still used to this day. Damar is a key component in late nineteenth and twentieth century glaze medium recipes. The resin adds a hardness and clarity to the medium different to a simple oil medium.
Synthetic resins are employed for the manufacture of artist’s varnishes. Their relative easy resolubility in solvent makes them unsuitable for addition to oil mediums.