Heating chert before knapping

[nebraska steve]

If someone tells you to throw the chert in a fire before knapping, make sure it is outside. My wife is still fussing about me throwing a hand full in the fireplace. It was pretty exciting for a few minutes.

 

[necchi]

:grin: , :haha: , :rotf: ,, :shocked2:

 

[Flint311]

Sort of a "4th of July Celebration" in January? Or, "we're being attacked" kinda fright? LMAO :rotf:

 

[bubba.50]

amazin' how much water a rock will hold ain't it?

 

[nebraska steve]

I've never been accused of being overly bright, and this was definitely one of my dimmer moments. and it was more like we are being attacked, than ooh,aah.

 

[Billnpatti]

Yep, this is one of those teachable moments where you learn never to put any rock except those that are absolutely bone dry in a fire. This applies to using rocks in a camp fire as well. If a rock has been picked up near water and exposed to the intense heat of a fire, it can explode with enough force to injure bystanders. But, you know that now. :hatsoff:

 

[FishDFly]

When water turns to steam, it expand 1,600 times.

 

[M. De Land]

Chert is baked in a kiln at about 4-600 degrees F. for something like 12 to 24 hours it is never subjected to direct flame for heat treating it.
Indians did it in sand pits with fire wood coals,layering sand between the coals and chert.

 

[FishDFly]

Chert is baked in a kiln at about 4-600 degrees F. for something like 12 to 24 hours it is never subjected to direct flame for heat treating it.
Indians did it in sand pits with fire wood coals,layering sand between the coals and chert.

Why? Curious.

 

[Billnpatti]

It is supposed to make it knap better. MD has done a good bit of knapping so he would be able to give a better answer than me.

 

[M. De Land]

I couldn't say it any better Bill!
I've knapped some of each and the heat treated always works easier and more predictably with the exception of Brown Chert from Texas.
The bit I have tried seems to work as well as the heat treated I have bought.

 

[Cbriggs57]

Some forms need to be heat treated to make the cryptocrystalline structure more uniform and more workable. The primitive archery and primitive skills folks do this a lot.

 

[Carl Fowler III]

Wondering how the native american indians figured out heating chert helped it nap better...accident or formulated? :stir:

 

[M. De Land]

Almost certainly by accident I would guess. Once discovered that heating made it easier to knapp then ways of accomplishing how to do it so it would not heat crack were discovered by trial and error.

 

[glrerun]

I purchased a food warmer like the caterers use from the Good Will for $25.00. It has a thermostat to 500 degrees.

I fill it about a third of the way with sand, place the stones with spaces between them, add sand to the brim and put the lid on. I set it at 500 Degrees and leave it in the garage until the next day.

then turn the unit off and remove the lid, walk away and let it cool on its own.

about a two day process, but I am in no hurry.

Works very well and cheap.