Two styles of toothed chisels, also called “rippers”.  Designed for use with pneumatic hammers, they were used to remove background from letters or carvings quickly.  Held at a 90 degree angle to the surface, the hammered away at the stone.  The lower the number of teeth, the faster, but rougher, the chisels would cut.  More teeth cut slower, put produced a smother cut.

Older chisels (1800’s and early 1900’s) were forged.  To sharpen them, the blacksmith would have to retemper the steel and then sharpen the teeth.  By the 1930’s carbide tips were popular because they stayed sharper longer and could be sharpened at the stone cutter’s shop with a carbide wheel.

Source:  Interviews with George Winburn and Melissa Phillips