Golden OPEN Acrylics stay wetter longer than regular acrylics (Heavy Body and Fluid). Thicker applications can be worked for hours, in fact, paint over 1/16" thick will dry EXTREMELY slow. This means that they also resist skinning on the palette during long painting sessions. Unlike most acrylics, Golden OPEN Acrylics can be used with natural fiber brushes (ammonia in most acrylic paint will deteriorate natural fiber brushes over time). They are great for blending, softening, shading, glazing and fine detail and can be used for a range of techniques including portraiture, plein air painting, monoprinting, and screenprinting. Golden OPEN Acrylics are compatible with most other Golden products.