For centuries, oil varnishes have been commonly made from resin.
What is resin?
In the context of art resin is a hard, amorphous substance used in varnishes and binding mediums for paints such as acrylics. Resins can be found in the secretions of trees or made synthetically. They are used to create sculptures in mixed media art and jewelry.
How to use resin for painting
By mixing resin with alcohol you can create your own homemade pastel fixative. Resins can also be used as varnishes for oil and acrylic paintings by thinning the resins with a solvent. For oil painting, a glossy resin called Damar is the most common traditional varnish. Damar resin is naturally made from the sap of coniferous Asian trees, and much more environmentally friendly than its synthetic alternatives. However, it yellows over time and must be removed and replaced after several years.