Turkey Roaster Burlington

Manufacture of stone tools, knives and arrowheads by lithic reduction

Turkey Roaster Burlington

nogie1717
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nogie1717
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Joined: April 6th, 2016, 2:43 pm

May 15th, 2018, 3:44 pm #1

Hey folks,

I posted this question around the various flintknapping forums on Facebook and did not get an answer.  Do I really need to hold Burlington at the max temp for 72 hours?

So the various heat treating info spots said that Burlington needs to be held at max temp for 72 hours and that seemed like a long time.  Two questions come up for me when heat treating - A. Workability and B. Color Change - and I wasn't sure if the long soak was necessary for either of those two.

Additionally, I was using a turkey roaster, so my max temp is an estimated 540, as the thermometer maxes out at 500 and took six seconds to re-register, about the same amount of time it takes to drop from 480 to 450 and I figure the higher temp has a quicker cooling rate (super scientific, I know).  So, I split the difference and held at max temp for 36 hours, ending up with a pinkish hue and increased workability.  It isn't the slick, my four year old can knap this, candy Burlington that I've gotten my hands on from time to time, but it is easier than raw.  Next time, I plan to hold about 8 hours as one guy said that's the max he does for any stone and see what comes of it.  I tossed in a flake of Bull Gravel that fell apart like an insecure high school basketball coach at the regional tournament and some Wyo Oil chert that slicked up real nice.  There was another couple pieces of some TX stuff that really came out slick, although it got too hot/brittle, IMO.  It was pretty gnarly raw stuff, though.  

I know it isn't "abo" or "traditional" and hope to someday do some fire pit annealing, but until then it is fun to play around and experiment.  If you don't think that tossing a rock in a turkey roaster and having it come out different color and texture is cool, then I feel sorry for ya.

Below is a pic of a still raw piece on the left and a heat treated biface on the right.

IMG_3649.JPG
Last edited by nogie1717 on May 15th, 2018, 7:20 pm, edited 1 time in total.
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Chippintuff
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Chippintuff
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Joined: January 21st, 2011, 12:25 am

May 15th, 2018, 7:11 pm #2

I do not have any experience using my turkey roaster on Burlington, but I can tell you generally what happens with other types of rock. I say generally because I have not kept data, but I do know about what to expect. Rocks that explode were probably heated too fast.

They need to sit hot but below boiling, about 200*F, for several hours to get the moisture cooked out if they are thicker that about 1".

The longer they stay at the max temp, the more the color changes.

I usually hold my rocks at the max temp 12-24 hrs, and that works fine, but it is not Burlington.

Some people say that it is unnecessary to hold rock at the max temp more
than one hr.

Check the temp in various parts of the turkey roaster. Mine (cheap $25.00) varies 75*F. I can put my toughest rock in the hot spots and the better material in the cooler spots and bake a variety at one time.

WA
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nogie1717
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nogie1717
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Joined: April 6th, 2016, 2:43 pm

May 15th, 2018, 7:28 pm #3

Thanks for the info, WA.  I do a 24 hour soak at 200 to start with any rocks I cook.  I use the word "any" liberally as this was only the third time I have cooked the stone.  Here's a question that probably only has an opinion as an answer, but when burying in sand, do you think there is much heat loss by taking the lid off and checking the temp different spots?  

My mother-in-law gave me the one I'm using and it is dated.  But even so, the temperature corresponds perfectly with where I have the dial positioned (checking the middle and sides).  I have yet to check right on the edge.

Cooking one flavor rock at a time is really good advice and one that I willfully chose to ignore in one of those "what the heck" moments.  :)
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WillmcUtah
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WillmcUtah
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Joined: March 12th, 2018, 2:46 am

May 16th, 2018, 12:14 am #4

I tried heating the Burlington I found in Missouri last month in a turkey roaster. Top temp it would hold was 426. I held it at that temp for 36 hours. Rock came out just slightly better than it went in. I’m not even going to try it again till I get something better
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cornernotched
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cornernotched
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Joined: April 27th, 2018, 11:42 pm

May 16th, 2018, 1:37 am #5

I'm new around here, but I've been roasting rocks for years, I ramp up to temp slow then hold for 12 hrs then ramp down slow. up and down to fast is what cracks rocks. and yes longer holds can change color. higher heat will get you the gloss. I tossed the lid and put a one inch ceramic fiber board on it. holds the heat in alot better witch will get you higher temps. pluss I drilled 3 small holes in it to put grease thermometers in, one in the middle one on each side. to get more accurate temp. and have found the sides will be hot hours before the middle gets even close. hope this helps
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Chippintuff
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Chippintuff
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Joined: January 21st, 2011, 12:25 am

May 16th, 2018, 4:14 am #6

I have never pulled the lid off to check anything while it is hot for fear that something will fracture.

I have **** insulation wired into the lid on my cooker, and it helps get the temp up a little higher, and I think it does a little to even the temp out all over the cooker.

I also have holes drilled into my lid and then use one long stemmed cooking thermometer. It is easy to move it around to check various places.

All my cooking has had sand in the cooker around and between the rocks. I think that helps prevent sudden temp changes. When I am ready to take the temp down on mine, I just turn it off and leave it closed till the next day. After it has been off about 18 hours, it gets down to 100*F, and I open it then and dig the rocks out. In my opinion, a lot of what works and what does not work involves all the factors like insulating the lid and putting sand in. A thing that works for one may not work for another because one is doing it one way (sand and insulating) while the other just stacks the rocks into the cooker and turns it on. Either way can work, but some fine tuning may be needed.

I agree that it takes a few hours for the temp setting to get to the middle of the cooker, but notice that rocks close to the edge, especially the back side (on my cookers) ramp up fast after each adjustment. They are the ones most susceptible to problems with ramping up or down too fast, especially in cookers that have no sand.

Just my opinions.

WA
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