The heart of Optimist Mixable Color is shellac medium. This magical amber liquid is the perfect binder for all kinds of pigments because it's strong, flexible, UV-resistant, and waterproof. Unlike acrylic mediums, our Colorless Shellac makes gorgeous transparent glazes when used in high proportions with color. Add Colorless Shellac Medium to Optimist inks to make them lighter, more transparent and glossier. Using shellac-thinned Optimist colors, you can make complex, multi-layered paintings. Paper and pigment textures are more noticeable, and the ink moves more freely. With high proportions of medium, you'll create thin, shiny layers that look almost like stained glass. With smaller proportions, you can achieve bright, high-chroma colors. What is Shellac? Shellac is made by insects, much like beeswax or silk. It is a reddish, resinous substance that is deposited on tree branches by kerria lacca, informally known as a lac bug. These ti