Forging Tools
Since ancient times, stonemasons have worked with hand-forged iron chisels. Since different types of stone have different properties, chisels are made according to their demands. As such, the cutting edge of a chisel for granite is more flexible and less sharp, while the cutting edge of a chisel for sandstone or soft limestone can be drawn out to a very sharp point and should be very hard.
Besides the shape of the blade, the hardening process is vital to obtaining the desired properties. As it hardens, the structure of the steel can be changed through rapid quenching in water or oil, so that it becomes much harder than normal metal. Next, the hardened area of the steel is gently heated again (tempered) to give it the desired toughness.
Photo: tempering colours, with temperature indicated. Steel type E1.4301. (Source: Bernhard1984 messerforum.net)
Of course, stonemasons are not blacksmiths, who learn their trade over many years. However, a good stonemason knows how their tools are made, and can, in the best case, make their own. Unfortunately, few chisels are forged by hand nowadays. Instead, stonemasons use chisels with carbide tips, which are much more durable and also show very good properties.
The advantage of hand-forged chisels compared to carbide tipped chisels is that the tools can relatively easily be given a wider, sharper, blunter, angled, or custom shape. A stonemason can therefore craft their own tools that are adapted to each new piece of work.
traditional stone tools
1. Scharriereisen
2.Abgewinkelte Eisen
3. Spitzeisen
4. Halbmond- oder Rundeisen
5. Zahneisen
6. Schlag- oder Beizeisen
7. Reissnadeln
8. Zweispitz oder Geissfuss
9. Schroteisen
10.Glattfläche
11. Kröndel
Chisels forged by hand are much more resilient than carbide tipped chisels. If the blade snaps off a forged iron chisel, it can simply be forged again. However, if the carbide tip snaps off, a chisel is broken and cannot be repaired.