Heat treating

[Desertdrifter]

I keep seeing videos where folks mention that the artifacts they are finding have been heat treated. How can you tell?

[dirtscratcher]

It depends on the material, but heat treating was used to make the material work easier, and on material like Flint Ridge would leave a very glossy look and bring out vivid colors If you compare two pieces of the same material side by side, it's easier to tell which was or was not heat treated.

[drdave514]

Agreeing with Dirt.

The material becomes more brittle and glassy and is easier to knap. The colors change and you start getting a lot of pinks, oranges, purples, etc..

[Desertdrifter]

Got it! Thanks for the helpful replies.

[tomclark]

Thanks to pugetsoundknappers.com for this chart of temps for heat treating different materials and comments. But I still wish knappers would quit it, muhaha.
http://pugetsoundknappers.com/how_to...t_Treating.pdf

Heat treating or "rawness" are also telltale diagnostic traits of particular type points and time periods......

[Buckeye]

Another way to tell is fine heat treated chert has an almost waxy-smooth feel, while raw is dry in comparison.

[uniface]

The waxy glossiness is generally under the dull exterior surface of the heated stone. When this is knapped-off in the process of making something from a baked blank, you end up with a glossy artifact.

But when a raw-chert artifact was beneath a fire later on, with adequate insulating soil, you've got a dull-surfaced artifact that was heat-treated by accident.

[marksimerson]

Bayport chert...Guess what blade is heat treated!

[dirtscratcher]

Well, I guess it doesn't make all material glossier, just more colorful. I don't see much Bayport down here in Ohio south of Lake Erie, but I don't recall seeing any heat treated, unless maybe I didn't recognize it for what it was. And now that I think about it I do have a big chunk that sorta looks like the pink and white piece.

[dirtscratcher]

Mark, now you have me wondering if these are Bayport. They actually show a lot more pink than the photo indicates. They've been a mystery material for me for years. They were found about 80 miles south of lake Erie. The larger one is about 2 1/2" X 2". All I'm familiar with is the dark gray version of Bayport, and little if any of that is found around here.