Heat treating chert with fire, (another thought)

[twisted hickory]

Is anyone finding this post interesting? I think it is mind blowing data. I cant wait to do it again!

I have been checking in. This is good information. I have some chert that I found the other day I think. I will use this to do some baking of rock myself
Thanks for posting this.

[iowabow]

@T.H. Your very welcome just remember to dig a pit build a fire and once it is out mix all of the loose dirt with the charcoal to made a new pit from. I believe this is why it has cooked the way it did.

The time is 1:06 temp 480 degrees about 7 degree drop per hour. That is a very slow downward ramp.

[Josh B]

Hopefully we'll be able to see some of the finished product tomorrow night or so!  This has answered a lot of questions I had about heat treating with fire, but I think it might have created more new questions than it answered.  I didn't make it home this weekend, but when I do, I will dig me a fire pit and have a few fires to try to recreate this experiment. I might even splurge on a pyrometer!  Shhh!  Don't tell my wife.  Josh

[iowabow]

In case you guys forgot this chert broken or not will be his as soon as our paths cross. I through a couple in for me but he gets all of those you saw in the video. So Josh it's up to you to pull this post up and give use your thoughts on quality good or bad.

[iowabow]

82 dollars just search k2 pyrometer.
I will do this again next week it is a very simple process and looks fool proof to me. I will re measure the sand depth so all of you will have a starting point for a 600 degree fire. Just remember the fire may climb toward the end.
Josh if you do this will you please keep notes so we can compare?

[iowabow]

I have not read anywhere  a description that defines the qualities of the pit built the way I did so unless someone has a name for the "pit preparation" I would like to call it a" JW Pit" because he is the funnest guy I know and you never know what he will say next. This was the funnest firing I have ever done and I never new for sure what was going to happen next!

So defined ...A JW Pit is a pit constructed in such a way as to have the remains of material from soil that consist of but not limited to, clay, small rock, sand, and charcoal, from previous fires mixed together. This material makes up the walls of the pit and as the firing burns out the charcoal  it leaves ash. The remaining material and air pockets then becomes an important element in retaining heat during the firing and cooling.

[RickB]

John, I've tried digging a pit before but have had problems with moisture seeping up through the ground. We've had 18 straight days with rain here in Columbia SC so the only way I could do it outside now would be in my washtub. Here's a link to your thread from last year when I commented on what I use to heat treat - see the photos. Rick B

http://www.primitivearcher.com/smf/index.php/topic,33532.msg442786.html#msg442786

[iowabow]

John, I've tried digging a pit before but have had problems with moisture seeping up through the ground. We've had 18 straight days with rain here in Columbia SC so the only way I could do it outside now would be in my washtub. Here's a link to your thread from last year when I commented on what I use to heat treat - see the photos. Rick B

http://www.primitivearcher.com/smf/index.php/topic,33532.msg442786.html#msg442786

Good info on that thread! Where does the time go lol. I gathered that sand and sifted it as you said and parked in the garage until I started this post wow. Too mant projects too little time. Again thanks for the help.

[iowabow]

8:23 temp 321

[iowabow]

5:91 am 182 degrees. I am going to let it cool before I pull it out.

[iowabow]

Interesting thing to think about is the dropping rate of the fire which is about 15-20 degrees per hour. This is equal to a packed kiln if not better.

[twisted hickory]

Can hardly wait to see your findings.

[iowabow]

I am headed home right now to check it

[Ryan_Gill_HuntPrimitive]

Curious to see how it turns out for you. I heat all of my rock in a pit under a fire. took a little trial and error to figure it out but I never went to the effort that you have with the meter and such.  mine has always been pretty straight forward.  bury 2-4 inches in dry sand depending on type of rock I'm heating, start a slow fire and build it to have good even coverage. I keep burning about  6-8 hours (depending on type of rock, some take longer and hotter than others). Then I let it go out and go to bed.  The next morning there are still red coals under the ash and I let them completely burn out which is usually by noon the day after initial firing. once the embers are out, I scrape off the ash layer, but not the sand.  by evening I can take the rock out and it's fully cooked and glassy.  I have made the mistake before of letting it cook too long or too hot and ended up with broken or really weak rock.   Your method is a bit different so I'm curious if there is much difference in the end result.  I have liked the open fire as well b\c I can multi task and fire some pottery while I am at it.  been really wanting to cook rock here lately, but summer in FL..... Rains every day!     good luck!   I read  through but I think I overlooked the type of rock you are cooking. I probably read it and forgot already..lol  so what flavor are you cookin?

[iowabow]

Ok the pit was at 130 and I could not wait so here is the group photo of the rocks from the pit. Not one crack all were great and intacked! The follow in goup of pictures will be details of the rocks and a little knapping and some pictures of the recovery