Stencil Brush – Size 4 . This natural bristle stencil brush features a one piece ferrule and wooden handle. A stencil brush is a specialist brush with short, firmly packed bristles. They are available in various widths, from small for tiny, detailed sections of a stencil to large ones for faster painting in of sections. The main advantage of a stencil brush over a normal paint brush is that it reduces the chances of getting paint under the edge of the stencil because of the stiff bristles.