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How to Heat Treat Flint Knapping Rock

by Jeremiah Blanchard
Learn how to heat treat rocks for flint knapping.

Learn how to heat treat rocks for flint knapping.

The art of flint knapping was practiced widely by many prehistoric and ancient indigenous cultures across the world. Flint knapping is the process of chipping off bits of a rock to form a point or achieve a sharp edge, which would then be used for hunting or as a cutting tool. In North America, evidence of flint knapping is found all over the continent, particularly in the southwest. Studies corroborated by the Journal of Archeological Science, show that many prehistoric flint knappers heated rocks to produce fractures. The heating process lightly fractured the rock which made chipping the rock easier. The process of heat treating rocks for knapping can still be performed today using the same primitive method.

Create a fire pit by placing large rocks in a circle of about 3 or 4 feet in diameter. Clear away any loose dirt or debris from the fire pit center.

Place the rocks you've selected for knapping in the fire pit center, and bury them about an inch or two deep. This will insulate the rock so that once heated, the heat will remain trapped and the temperature will steadily increase.

Start a fire and keep it burning for at least eight hours by adding logs about every hour. Let the fire burn out overnight.

Restart the fire in the morning and let it burn for another hour or two. The coals at the fire pit bottom will accumulate and stay red hot for at least 12 hours. This will continue to heat the rock at a steady temperature

Dig the coals out of the fire-pit and retrieve the rocks one day later. Ensure that you've waited at least 24 hours after the fire died out. The coals may still feel warm so be careful when digging the rocks up. The rocks may appear a different color than before you buried them. This is indicative of a lightly heat fractured rock, and will be ideal for knapping.

Warning

  • Use extreme caution when handling hot rocks or starting a fire. Ensure that you have permission to have a fire on your property, or that you're in a designated fire pit area at a campground.

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