FOR GOLDEN OPEN ACRYLICS-- TWO MEDIUMS AND 1 ADDITIVE FOR ULTIMATE CONTROL: Use OPEN Mediums and Thinner to maintain the maximum working time of OPEN Acrylics. OPEN Acrylic Gel (Gloss) is recommended to adjust color strength and translucency while maintaining consistency. OPEN Acrylic Medium (Gloss) is formulated to a lower viscosity for a more fluid mixture with increased flow. OPEN Thinner contains no binder and is used to maintain and adjust the workability of colors on the palette without the use of water mist and moisturizing palettes.