Blockx Amber Oil Color Mediums : Blockx is the only company that has sold amber for over 100 years and can guarantee time tested results. Amber is the finest of all resins. Just a few drops mixed into your colors will make them more transparent and radiant. Pictures painted with amber do not require varnishing since the color is protected by the resinous amber—paint film becomes plastic, neither brittle or friable. Amber is one of the finest varnishes in the world today and may be used to protect painting as soon as the film is dry to the touch.