In this part of the tutorial we harden the blade of the knife by heating it up to a high temperature and then quickly quenching it.

Part 1 of this tutorial is here

So, heat up the knife. And for all of this we are not so much concerned about the handle portion of the knife, just the bladed section.

We are looking to get that blade glowing red hot. Literally glowing red hot. And there is a good way to figure out just when it is at the right temperature. This is called Curie temperature. And it is at the point where a magnet will no longer stick to it.

Checking it with a magnet.

This picture gives you a good look at how it develops. The orange and red glow is pretty good. They yellow part is a bit over heated. On the left side there it still needs heating.

So, move the knife around in the fire, adjust and tinker with the coals. Try to get the whole blade heated evenly a glowing red orange.

Ok, it gets up to color and passes the magnet test. Quench it quickly in oil.

This can be new or used motor oil or vegetable oil. Just be safe about it. That fire is dangerous and can get out of control.

Here is what it looks like.

That knife is now hardened! We need to temper it in order to soften it up a bit so it isn't so prone to breaking.

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