first try at heat treating in Flintknapping

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first try at heat treating

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thisiswhatisee	first try at heat treating	Lead	[-]
Posts: 69 Mar 14 11 4:45 PM Reply Quote More My Recent Posts	Tags : None bought a roaster this weekend, put some horse creek, burlington and keokuk(?), bloodstone, and some other random things in it. cooked for 8 hours first and saw no results so i cooked it all again for 24 hours. the only ones that changed colors. some of the pieces of horse creek and burlington seem a little slicker, but the roaster doesn't get hot enough to really cook the burlington.
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Chippintuff		#1	[-]
Posts: 1040 Mar 14 11 7:36 PM Reply Quote More My Recent Posts	There was a man at the Bandera Knappin who said he was using the microwave to heat treat. He said that the first time he melted the dish the rock was sitting on. I have doubts about using a microwave. It seems to me there are too many variables that affect heating time and effect. It does sound like a fast way to get the heat through and through the stone though. I have serious doubts that a microwave will work satisfactorily and safely. Have any of you tried it? This may be one of those subjects that has been whipped to death before I got on here. W.A.
NewbowPA		#2	[-]
Posts: 204 Mar 14 11 8:12 PM Reply Quote More My Recent Posts	I would be very leery of using a micro wave oven to heat treat. At the same time, it does have an appeal so if anybody conducts some controlled experiments (with an old unit, in the shed, not in the kitchen) please post your results. I am leery because all rock that hasn't been carefully dried will contain water. The microwaves will evaporate that water first and possibly catastrophically. I don't know if that evaporation could be effectively controlled. Doing a little research, I discovered that microwaves can have an effect on silica like in glass, clay and most knappable rocks so maybe it will work.
Chippintuff		#3	[-]
Posts: 1040 Mar 15 11 6:29 PM Reply Quote More My Recent Posts	I tried a few pieces of TX flint in the microwave with a jar of water there to absorb some of the waves and prevent burning the oven out. I began with a defrost cycle for several minutes, then began running longer and longer times with about a 3 minute break in between runs. The last two runs were for 6 minutes each. The rock got pretty hot, but it's knapability did not change. I was chicken to push my luck. W.A.
MatSu		#4	[-]
Posts: 517 Mar 16 11 5:23 AM Reply Quote More My Recent Posts	Chippintuff wrote: I tried a few pieces of TX flint in the microwave with a jar of water there to absorb some of the waves and prevent burning the oven out. I began with a defrost cycle for several minutes, then began running longer and longer times with about a 3 minute break in between runs. The last two runs were for 6 minutes each. The rock got pretty hot, but it's knapability did not change. I was chicken to push my luck. W.A. What toppings did ya use when it was done? Ken
Chippintuff		#5	[-]
Posts: 1040 Mar 16 11 5:54 AM Reply Quote More My Recent Posts	Sharp Cheddar and Hard Apples. W.A.
AwakenedBuddhist		#6	[-]
Posts: 97 Apr 14 11 12:47 PM Reply Quote More My Recent Posts	I heat treat right in my oven,gets up to 600 degrees
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stoneknife		#7	[-]
Posts: 1399 Apr 18 11 3:59 PM Reply Quote More My Recent Posts	Thisiswhatisee - What's that in your roaster? Dirt? If so, use playground sand - available at Lowes, Home Depot, etc. Also, did you completely bury the rock? You need to put all of your rock in the roaster and fill with as much sand as the roaster will hold - to the point where you pile it at the top so the lid just fits over the top - absolutely full as possible. The next step is to set your roaster on 210 and heat it for at least 8-10 hours. This purges the water from the rock (heating rock above that will boil the water inside the rock and fracture it). After you have done this, crank it up and let it heat about 24-48 hours. Some people prefer long runs for rock that responds to color change. Some prefer shorter runs. After this, you should probably ramp it down every few hours 100 degrees or so at a time until you get to 250 or so and then you can cut the power and let it completely cool, which will take 12 hours or more. Get a probe thermometer (they make them for turkey friers that go up pretty high). I suspect that you are just not getting enough heat due to the way you are using the roaster. There is plenty of info on this website about this and some are far more cautious than me, but with all that sand in there, nothing happens quickly, so don't worry (IMHO) about 50 degree ramps and the like. Try this and let us know what happens. And....ignore that microwave BS - you are using a turkey roaster.
stoneknife		#8	[-]
Posts: 1399 Apr 18 11 4:02 PM Reply Quote More My Recent Posts	Also...it doesn't matter if you heat one rock or 20 lbs.....the roaster is hottest on the sides and bottom. More sensitive or lower heat rock can go in the middle. Your roaster should work well if you use mass (all the sand) to hold and disburse your heat.
thisiswhatisee		#9	[-]
Posts: 69 May 14 11 8:12 AM Reply Quote More My Recent Posts	stoneknife- thanks for the tips. I am using sand, and I did bury them, but i'll have to go get more sand to be able to fill the roaster to the top. some of the burlington I put in had some slight changes that didn't affect the entire rock, so the longer cook time sounds like its just what I need. i'll keep you posted on what happens.
thisiswhatisee		#10	[-]
Posts: 69 Feb 23 12 6:46 PM Reply Quote More My Recent Posts	so after attempting a few more cooks in my roaster, I noticed a lot of dust and the volume of 'sand' slowly decreasing. Think i had some bunk dirt with sand particles in it..... got some better sand and loaded up some rocks I collected in Pike County, IL, this past summer. Cooked a flake from a chunk and it's the only good before & after photos I have from this batch. Lots of fossils in this stuff, hopefully be able to knap it soon. flake broke in two while it was raw. you can see one of the pieces had more heat applied to it and was effected more by the heat. thanks for looking!
Chippintuff		#11	[-]
Posts: 1040 Feb 24 12 2:56 PM Reply Quote More My Recent Posts	Is it easier to chip since it was cooked? If the cooking was succcessful, the chipping will be easier and the new flake scars may be glossier. The color change you have makes me think you got it about right. W.A.
aztecstoneandflint		#12	[-]
Posts: 688 Mar 8 12 8:53 AM Reply Quote More My Recent Posts	Hard to tell from your picture but if your pan is removable, take it out to get more heat. Also the top outside corners get the hottest so put your Burlington there. One other thing would be to use vemiculite instead of sand. It works the same and is less mass to heat.
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first try at heat treating

first try at heat treating