My Spinner

W

W. Hilditch

Active member
I have a spinner Dutch oven. The warpage is very mild and you can’t tell unless you are looking for it, but the challenge was there. It is a BSR #8 Century.



I was reminded of an old email that said: “I’m a man. I can fix that!” I know, I know but I needed to find out for myself. So I made my plan to try and reverse what might have caused the warpage. Best to do this outside so I made a fire and heated up two quarts of used deep fryer canola oil in my chicken fryer to over 400° F. Smokin’!



While the oil was heating I got the DO out of the fridge and put it in an ice water bath to keep the outside of the bottom cool while I heated the inside. I then poured the hot oil into the DO.



Faced with a long wait and that nice fire I decided to take advantage of it so for the next two + hours the baby back ribs cooked low and slow on the CI grate. And they were served with CI tongs so that should make it OK for this site. Time to eat before cleaning up that mess I made as I spilled some oil in the water.



Bottom line, the DO spins just as nice as it ever did with no perceptible change. On the positive side, I got this challenge out of my system and those juicy ribs sure were good!

Hilditch
 
Follow-up: I assumed a difference between the inside and outside temperature of cast iron could cause warpage and be reversed. It seems I was wrong on all accounts. I should know better. Made an a** out of me.

After doing some homework it appears grey cast iron will warp once due to overheating above 1,000° F. At that point, closer to 1,500° (cherry red) the carbon will form into graphite and glass crystals that harden the cast iron. To reverse the process is not an option without a special chemical treatment at high heat to soften the crystals or a meltdown at over 2,000°.

So cast iron can be hardened like steel that is forged for a knife. It then becomes more brittle and can more easily crack rather than expand in a moderately high temperature environment. Like a self cleaning oven or putting the piece in a fire to clean it.

Due to the infinite number of material combinations, melting options, cooling options and reheating temperatures no two pieces will react exactly the same to warping conditions. However, the common denominator appears to be that once the grey cast iron has been warped, the crystals have formed and it is not reversible.

So my spinner probably once saw cherry red while empty, not just higher heat on one side. End of story.

Hilditch
 
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Well you just took the wind out of my sail. I picked up a spinner #10 BSR for $2 at a thrift store. I was going to try and get it real hot and stack some bricks or something on it. Maybe use the oxyacetylene torch and hydraulic press at work.
 
Shawn, I'm now thinking like this: After I learn how to straighten a warped camshaft, I'll take on warped cast iron hollowware.

From what I understand even drilling a hole in hardened cast iron is like drilling granite. Granite laughs at modern drill bits. It can be ground, but not drilled.

We figured out how coal was made into diamonds but are still a ways off of knowing how to reverse the process to create energy. Somehow cast iron and diamonds seem to have something in common.

Hilditch
 
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