The flat chisel, like the point and tooth chisels, is a metal hand-held tool which is struck with a metal hammer, or wooden mallet in some cases. It consists of a shaft, 15-25 cm long and 1-2 cm in diameter, with a flat and sharpened cutting edge perpendicular to the line of the shaft. The width of the cutting edge can vary significantly, between 0.5 and 10 cm; the wider varieties are sometimes called bolsters or droves. Further variation is found in the profile of the corners of this cutting edge. Sometimes they are rounded so that they do not catch on anything during delicate work but often they are left squared and sharpened for the careful application of detail and especially for letter-carving.
The flat chisel is typically used for applying detail, smoothing surfaces and finished forms. It is usually held at 35-60° to the surface of stone but like other chisels it can be used in various ways, carefully to smooth or more roughly to shape quickly. The traces left behind by the flat chisel tend to consist of almost smooth sets of parallel straight lines, sometimes barely noticeable when the carver has worked particularly carefully.