Concrete Turpentine is now only available as Rosin for polishing violins and for use in printmaking. No one today recommends it for artistic use. It is considered an adulterant in paint and varnish. Blockx Amber Varnish and Amber Alchemy Paints and Varnishes , as listed above under mediums, are the only producers that I know of for amber varnish. Copal Resin , when it can be found, is today only used as an ingredient in mediums, and not in final varnishes so far as I know.
Quality is non-uniform.
When applied with Poppy Oil this varnish gives extreme brilliance to the picture. The varnish increases the drying rate and gloss quality of your finished paintings. The company does not list the ingredients in the promotional literature that I have. Conserve-Art is a superior quality varnish that is readily removable over a long period of time with turpentine or any odorless turpentine substitute without harming the original painting. The varnish dries quickly to a non-yellowing film.