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She started constructing backdrops, gluing together Popsicle sticks, molding things from self-hardening clay.

A large gray ball of self-hardening clay and a black medicine ball are also on hand as three-dimensional equivalents.

Of course, what has been said about burning applies more particularly to carbon steel, but even self-hardening steels are not improved by being over-heated at the stone.

Its alloy is much used for high-speed cutting tools, the steel hardening when cooled in the air and being called self-hardening.

Molybdenum is used to increase the hardness to a high degree and makes the steel suitable for high-speed cutting and gives it self-hardening properties.