HEAT TREATING STONE
The stone material that are covered here in, is material from the Hartville uplift and surrounding area. These materials include Agate, Jasper, Chert and Quartzite. Exact temperatures may very somewhat with personal preference as well as the knapping method used. If in doubt use lower temperatures. Try a sample first.
As a rule percussion flaking requires somewhat harder material than pressure flaking so, for example if you chose to Jasper as your medium and your chose to percussion flaking you may find that it works best with no heat treating but if you are using pressure flaking you may find that heating the material may make it work better.
Only familiarity with the material will allow you to make the correct hardness decision.
Below are approximate temperatures for pressure flaking materials.
About all knappable materials in the Hartville Uplift will fall into these 4 categories
Try this heat treating method . If you are heating slabs or thin bifaces ,and have access to a gas or electric cooking stove . Yes the kind that you have in your kitchen. WARNING: DO NOT DO THIS IN YOUR HOUSE IF YOU USE SAWED SLABS. MOST WEMEN DO NOT LIKE THE SMELL OF BURNED OIL IN THEIR KITCHEN.
Here is how it works.
Place the stone to be treated in a metal contained. Put the container in the oven. Turn the temperature to the target heat listed below.
Leave it at that temperature for 3 hour. That’s it……… Let it cool for at lease 5 hours. You’re ready to chip until your hearts content.
Agate…….500
Jasper……400
Chert…….425
Quartzite…450