Wooster Cutter 2-1/2 in. Firm Flat Paint Brush for oil-based paints, varnishes, shellac, alkyd enamels, oil stains and oil-based polyurethanes. Chisel construction. A flat brush of this size is ideal for baseboards, cabinets, furniture, moldings, railings, shutters, and gutters while an angle sash brush of this same size effective for window frames, casings, door moldings, and cutting in edges of walls, ceilings, and baseboards.