Princeton Catalyst Polytip, Brushes for Acrylic and Oil, Series 6450 Short Handle, Mottler, Size 50 Polytip Bristle brushes are another Princeton breakthrough that advances the science of synthetic hair Tip of each individual hair has been split to replicate the natural flags on the finest natural bristle Holds a higher volume of paint while providing a smoother application Designed for use with medium to heavy-bodied acrylics and oil paints Mottlers are large flat brushes that hold a large amount of paint in order to cover large surface areas and are commonly used for murals, washes, faux finishing techniques.