Open Acrylics are a highly pigmented, professional, and slow-drying line of acrylic paints.The increased working time expands their use to include more traditional techniques once only possible with oils, such as portraiture and landscape painting. They are suitable for some printmaking techniques.- Stays wet for longer periods of time.- Economic; requires less paint = less waste.- Ideal for portraiture, landscaping and printmaking. Because thick applications dry slowly,  it is recommended to use them thinly (< 1 mm). Drying time can be accelerated by mixing Open acrylics with faster-drying acrylics such as Fluid and Heavy Body colors.  Because Open acrylics dry slowly, painters who cover their palettes or use sealed containers have been able to use the same colors for weeks, reducing the amount of paint wasted and preserving color mixtures for future use. In addition, brushes that have been unintentionally left out for many hours can still be cleaned. Not for use with oil paints. Do not allow the product to freeze.