Synthetic brushes are man-made of either nylon or polyester filaments. They can be tapered, tipped, flagged, abraded or etched to increase color carrying ability. Often, synthetic filaments are dyed and baked to make them softer and more absorbent. The common name for this filament is "Taklon".
Advantages of synthetic brushes are: 1) They are less prone to damage from solvents, insects or paints. 2) They are easier to keep clean than animal hair brushes because the filaments don't have animal scale structures to trap paint. 3) They are less prone to breakage and are durable on many different surfaces. 4) They are better suited for painting with acrylics because a synthetic filament will withstand the caustic nature of acrylic paints with less damage.