workable stone

[paulc]

Hey all, I have another load of Texas stone via the online auction site.  I cooked it following Jack Crafty's "recipe" in his signature line...didn't seem to make much of a difference...I still have to swing like I am trying to kill something in order to get flakes to come off.  They are often pretty good flakes but there is nothing relaxing or enjoyable in the process....I watch Jack Crafty videos on youtube and Jack it appears you are often simply letting you hand fall and good flakes come off..

Do I just not have access to that quality of stone?  Any thoughts or advice?

Thanks, Paul

[Wolfmanjack]

Take this with a grain of salt cause I’ve only been doing this a little over a year.  Some Texas rock I’ve used is just super tough stuff.  I’ve tried heating it and it just will not behave.  Maybe getting the temperature higher may be the key but my turkey roaster won’t tame it.  With that being said some of the Texas rock I have tried turns super slick after heating and is a joy to work.  The same can be said for the citronelle gravel that I have access to.  Heat transforms some pieces almost miraculously and some pieces are just stubborn.

[JEB]

Some Texas cooks easy and some don't. That river cobble is a beast to try and tame.  I gather my own when I drive thru Texas and refuse to pick up river cobble which is usually found in front of every restaurant in Texas and at landscape business. There is a knapper that I haven't seen post here in awhile, that can make real nice points pit of it.   

I would re heat some of it to see if that helps. I use a turkey roaster with layers of beach sand between layers of rock. Seems to heat up pretty good for me. I also let the rock cool on it's own which usually takes a couple days.

[paulc]

Seller id'd the stone as Edwards Plateau material...which means nothing to me :-)  Thanks for the insight.  I have a turkey roaster and a toaster oven...both about the same results.

Paul

[Tower]

I’m a sucker for good landscaping cobbles.  But JEB is right.  Most will cook at 350* on the light end to 425* on the high end but there are some tough ones. After a while you kinda get an eye for the stone that need to go much higher .  I tend to spall & biface it out then cook it in the ground about 4” deep in packed soil.  I’ve reached 600* & it usually takes 2 days to cool down enough to hold it.   The color change can be quite remarkable.  Here is a point I made from a cobble.  Not my prettiest point but it will make short work of a whitetail.

[Tower]

A better pic

[paulc]

I was debating taking some stone straight from the toaster oven and just throw it in a fire...maybe I should try some buried stuff first.  Of this batch of stone it seems 1 out of three stones comes out good and slick but man it is still super tough...

Thanks, Paul

[Hawkdancer]

Some one a while back suggested sand over and under the stone and burning a 20 lb bag of charcoal over it.  Might as well broil your meat at the same time!
Hawkdancer

[JEB]

I wouldn't throw any rock into a fire.  Dig a hole, put some rock in it and cover it back up and build a fire over it. Not a lot of your rock but enough to run an experiment with it.

[gutpile]

go on ebay and buy some of the georgetown flint... get a box for like 57 shipped..around 30lbs I think.. I am hooked on that georgetown... gut

[JackCrafty]

PaulC, what are you normally working with? If you've worked mostly glass, the Texas rock will seem really tough.

Texas chert that doesn't heat well is pretty rare. It can sometimes be a lot like high grade rhyolite (which doesn't respond to heat). If it's Edwards plateau chert, it should be good stuff. There might be something wrong with the thermostats in your oven(s). You might try installing a thermometer to check the actual temperature during the process.

Throwing some of the stone directly into a fire is not a bad idea. If it pops, then it's good quality and you just need to find the right temperature using a good oven, roaster, or kiln. If nothing much happens to the stone after the fire dies down, then the rock you have is poor quality.

[JackCrafty]

When I heat treat in a "primitive" way, I don't bury the stone. I arrange the flakes and spalls around a bed of coals and heat treat in the the open.

[JEB]

Will have to agree to disagree Patrick on tossing rock in a fire. Cooking flakes and spalls the way you do is one thing but tossing rocks into an open flame can be very dangerous. I have had them blow up on me and my family when making a fire ring out of rocks that unknown to me were wet inside. And when they blew up chunks of rock flew everywhere. Thankfully no one was injured. 

[JackCrafty]

Flakes of chert or flint do not explode. They pop. You can usually recover all the pieces because they do not travel. I'm not disagreeing with you JEB, just FYI.

Moisture content of the stone is important. For those who don't know, wet stone and fire do not mix.