Heat Treating

[HoBow]

I found the following table. Not sure how accurate it is, maybe someone else can chime in:

Agate Brazilian - 450-500

Agate India - 500 

Agate Mexican - 500 

Agate Montana - 550 

Agate Moss - 450 

Alibates - 425-500

Bloodstone - 500

Burlington - 600-650 

Coral - 450-600 

Dacite - NONE 

Flint Ridge - 500-600 (set the roaster at 200 degrees for two hrs then increase until the max temp. is reached and leave it for 12 to 24 hours)

Flint - Fort Hood - 400-550

Flint - Georgetown (Blue and Black) - NONE

Flint - Georgetown Banded - NONE to 400

Flint - Knife River - 350 - 450 (Do NOT overheat or it could pot lid)

Flint - Danish - 300 -350

Flint - British - 300 -350 (hold time could be 6 hours)

Jasper Red - 500 (very hard stuff to work)

Jasper Sunset 450-475 

Jasper Fancy 450-500 

Jasper Picture 525 

Kay County - 500-600 

Novaculate - 700-900 

Obsidian - NONE 

Pedernales - 450 

Petrified Wood - 300-450

Does anyone know what dictates the differences (ie mineral content, moisture content, etc.)?

[Timo]

Jeff, that looks pretty good, but I have found that a long soak at a lower temp can yield the same results as a higher degree for a short period.High grade rock does not need to go as high as the table says. It takes alot of experimenting!

As for moisture: I run all fresh rock, surface pickup/quarried, on a long dry cycle at 200 degrees, at least for 24 hrs,sometimes for 36 depending on how much moisture it has.Better safe than hearing a constant..."ping"

[leapingbare]

Iv got brave with heat treating. I'll cook a load of chert the same day i picked it up outa a creek. I'll let it dry at 250* for 2 hours then ramp it up 50* every 30 mins till i reach target temp most rock i let soak for 8 hours then i just tern my oven off and wait 5 or 6 hours then open the door and wait another 3 hours then i take it out. I guess the TN chert i cook is more forgiving then most.

[Timo]

Maybe Jesse! Might be that it is higher grade rock?

 I know that if I was to do that with the Burlington around here,I would have alot of very small pieces.

[Wolf Watcher]

The agate temps are way too high.  For example Montana Moss Agate cooks at 350 and most Brizilain at 400.  I have a good book of heating temps by Waldorph and will bring some copies to the Classic!  Joe

[cracker]

Anyone got a procedure for the coastal plains stuff like I got around here.

[leapingbare]

Coastal planes is easy.. 500*  let it dry at 250* for 3-4 hours and ramp it 50* every 30-40 mins. Soak it at 500* for 8 hours.  thats what i did and it worked ok.

[cracker]

Thanks Jesse.

[mullet]

 Jeff you can destroy some of that Coral I sent you if you cook it as high as that chart says. I spall it and the small pieces I put in the toaster oven and crank it up to 425 and let it go all night. Unplug it in the morning and open the door in the late afternoon. Or cover it with about 3" of sand and put a large bag of charcoal on it and let it burn till it cools on it's on.

[jamie]

ive done fancy jasper in the oven at 400 for 3hrs and see a major difference.

[leapingbare]

that load of horse creek i cooked terned out grate. i let it dry at 250* for 2 hrs then ramped it up 50* every 30 mins to 475* i let it soak for 8hrs.
 Some of its just glassy!

[mullet]

 I never tried to heat the Horse Creek.

[El Destructo]

I still have that big ole Rod Oven...just perfect for cooking all the way up to 600 degrees....was going to bring it to the Classic...but it looks like that all over for this Year....Sux too.......