With hammerhead. Length 200 mm.
Lettering chisels or flat chisels can be used to carve lettering and details out of the stone very well, but also to shape edges or - depending on the width of the cutting edge and the size of the stone - to smooth surfaces.
Sculpting tools made of carbide or with carbide inserts are particularly suitable for carving hard types of stone. Carbide tools require less re-sharpening during work, as the material is so strong that there is less abrasion than with forged steel tools. The carbide cutting edge therefore has a longer service life. However, if carbide chisels are ground very sharp or thin, careful working is required, as carbide is a brittle material due to its hardness and can easily break when ground thin. Levering movements when hammering can also lead to breakage or loosen the carbide pin from the steel casing.
The rule of thumb for hard stone is: the harder the stone, the blunter the cutting angle of the chisel should be. With hard stone such as granite, the chisel is placed at almost a right angle and the stone is virtually pulverised. The chisel therefore has a very blunt cutting edge. For crystalline stone such as hard marble, a more pointed tool with a sharper cutting edge is required. The chisel is set flat so that the stone can chip off without damaging the underlying crystalline structure.
Carbide chisels can also be used for working sandstone. As sandstone is highly abrasive, forged steel chisels can wear relatively quickly. Carbide cutting edges have a longer service life due to their hardness. However, it should be noted that the carbide pins are usually set in steel.
As with crystalline rock, pointed chisels tend to be used for working sandstone: the aim with this type of rock is to destroy the bond between the sand particles when striking, for which a pointed tool is better suited than a blunt one. However, the same applies here: for very hard sandstone, use less pointed chisels that are less likely to break.
