braat
spending too much on rocks
Member since December 2016
Posts: 350 
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Post by braat on Oct 4, 2019 15:15:31 GMT -5
In another thread I tried cooking rocks in a slow cooker and it didn't enhance or change any colors on the rocks I tried...the slow cooker wasn't hot enough according to comments and what I'm reading. So I went on a hunt for a cheapie turkey roaster and found one for $7 on a local Facebook buy/sell page. I cooked up a batch and saw definite color change in some of the rocks..I forgot to take before and after photos so I did another batch which are what you see in the photos. I used previously tumbled rocks for both batches as I wanted to see what effect it would have on the shine as well as any color changes. I removed the roaster inner liner/pot (or whatever it's called) as I read that would raise the temperature. I put an inch or so of kitty litter on the bottom of the now empty roaster, then a layer of rocks, then another inch of kitty litter and then fibreglass insulation between the kitty litter and the roaster lid. For future reference I wanted to compare roaster dial settings to actual core temperatures so I put in a 200-1600 Flue Gas thermometer with the tip inserted in the middle of the rocks and kitty litter and the dial visible through the see-through part of the roaster lid. I started the cook at the 150 setting and raised the temp hourly by 50 to it's max setting of 450. I turned it off after an hour at 450 and let it cool overnight. Thermometer readings showed actual core temps hit 500 plus at the 350 setting and didn't increase much after that. Results were mixed.... some didn't change at all and most changes were to a darker color but nothing too dramatic. The Mookaite (3rd row) was affected the most color-wise and the inclusions in the second row agates are more "visible"now than before. One of the agates had multiple cracks after the cook as well (after photo doesn't show it). Some of the local rocks in the 1st, 4th and last rows have more contrast/definition than before. The shine on all of them was not affected that I can see. So for me I'm not sure if this is all worth doing for future tumbles at least for the color change part...I'm reading cooked rocks might shine up better so I'll maybe try a couple batches and see how that turns out. Worst case I can cook food in it... Before  Before 1 by Glen Braaten, on Flickr After  After 1 by Glen Braaten, on Flickr |
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Post by RickB on Oct 4, 2019 16:00:10 GMT -5
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braat
spending too much on rocks
Member since December 2016
Posts: 350
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Post by braat on Oct 4, 2019 18:05:10 GMT -5
Tks...all info gladly accepted... |
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Post by rockpickerforever on Oct 4, 2019 21:59:36 GMT -5
Rick, I located a heat treating thread from 2017. Eight pages worth of info (and banter, lol). Those were fun times. Five years previous to that were even better. Heat treating-with a simple campfire(page 5)
Using a plain campfire is on page five. Probably info repeated from the 2010/11 thread you mention. |
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braat
spending too much on rocks
Member since December 2016
Posts: 350
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Post by braat on Oct 5, 2019 0:36:33 GMT -5
Rick, I located a heat treating thread from 2017. Eight pages worth of info (and banter, lol). Those were fun times. Five years previous to that were even better. Heat treating-with a simple campfire(page 5)
Using a plain campfire is on page five. Probably info repeated from the 2010/11 thread you mention. Awesome! A mother lode of cooking info and inspiration in there. I'm going to have to be more diligent in using the search function here... Thanks! |
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Post by orrum on Oct 5, 2019 8:48:13 GMT -5
You need to go to 200 and hold then go back to no heat and cool. This gets the internal moisture out so they dont explode, crack, fracture or "pot lid". Then go up to full heat. You can let the soak at full heat overbite too. It not only changes color but changes the rock so you get a more waxy glossy finish when you cut them. Great job!!!
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braat
spending too much on rocks
Member since December 2016
Posts: 350
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Post by braat on Oct 5, 2019 14:29:10 GMT -5
You need to go to 200 and hold then go back to no heat and cool. This gets the internal moisture out so they dont explode, crack, fracture or "pot lid". Then go up to full heat. You can let the soak at full heat overbite too. It not only changes color but changes the rock so you get a more waxy glossy finish when you cut them. Great job!!! Thanks! I'll try all what you said in my next cook. I just clued in I'm boldly going where you and others have been long before so I'm going to absorb it all before deciding how to push on. One thing I know is I need to monitor the temperature better. The flue gas thermometer I used was all over the place in the 2 cooks I did. I'm guessing because it was designed to be placed in the exhaust stack airflow of an oil burning house furnace (which is what I bought if for long ago) and now I'm trying to measure temps with only an inch (or so) of it's 3.5 inch length in kitty litter. I'm going to check out the BBQ thermometer idea and if anybody's got any other cheapie ideas how to better measure temperature I'm all ears!  IMG_4916 by Glen Braaten, on Flickr  IMG_4919 by Glen Braaten, on Flickr  IMG_4918 by Glen Braaten, on Flickr |
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Post by RickB on Oct 5, 2019 14:57:01 GMT -5
I bought my two 12 inch long bbq thermometers at Lowe's hardware store.
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Post by orrum on Oct 6, 2019 5:52:44 GMT -5
Fill the cooker all the way up with kitty litter then the insulation and then the lid with a weight to hold it down. The rocks that are already bbn polished dont show the colors correctly. The real color change is inside the rock plus cabbing or tumbling grinds and shows it different! You are doing great, keep on experimenting! Walmart has digital thermometers cheap. Drill a hole in the lid to push the thermometer in.
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braat
spending too much on rocks
Member since December 2016
Posts: 350
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Post by braat on Oct 6, 2019 18:08:24 GMT -5
Cook-n-bake #3 is in progress.Thought I'd give the flue gas thermometer one more try with a couple changes (in the photos)... I added kitty litter so it's 4'" deep now and made a hole in the insulation so the thermometer sits lower/closer to the kitty litter so between the 2 changes all or most of the thermometer's 3.5" length is in the kitty litter. Also added another layer of insulation on top of existing. So far it seems to be tracking dial settings better but thermometer readings are (still) nowhere's near dial settings which is what's causing me to second guess thermometer accuracy. On this run dial settings of 100, 150, 200, 250, 300, 350, 400, and 450 give respective thermometer readings of 180, 240, 350, 400, 450, 710, 900, and 1000+. So either the roaster is on steroids or my thermometer is out to lunch. I'm ramping up at 5o degrees per hour and will hold at max temp till bed time then pull the plug overnight. Don't want to burn the house down in my sleep  I'm cooking rocks that are the same as the green ones in photo 3... they are local river rounded rocks that I haven't been able to shine up in previous rotary or vibe tumbles. For this run I don't really care what happens colorwise but am wondering if cooking them might make them able to shine up better? Knowing what they are might also help with a cook recipe? I couldn't google ID them so if anyone can help ID them I'd appreciate it....  IMG_4920 by Glen Braaten, on Flickr  IMG_4921 by Glen Braaten, on Flickr  IMG_4922 by Glen Braaten, on Flickr |
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I'm cooking rocks that are the same as the green ones in photo 3... they are local river rounded rocks that I haven't been able to shine up in previous rotary or vibe tumbles. For this run I don't really care what happens colorwise but am wondering if cooking them might make them able to shine up better? Knowing what they are might also help with a cook recipe? I couldn't google ID them so if anyone can help ID them I'd appreciate it.... 
