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I Forge Iron

Clay types for rivet forges


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Hi again!

So, I’d like to begin with what I have and what I’ve tried so far. I have a very thick cast iron rivet forge. If this was EVER meant to be portable, then it must have been for MUCH bigger/stronger dudes than me! (6’4”, 275lbs)

It has no identifying marks or instructions to clay, but it certainly could have as it’s missing the original wind screen and I believe the tuyere/champion blower/mounting bracket may have come from a different forge.

Currently, I’m struggling with ways to keep the grate in place. When I got the forge it came with a cast iron floor drain of sorts and it was cemented down with what appeared to be furnace cement. It eventually dried up, cracked and completely detached from the forge. Since then, I was given some cone 6 pottery clay. First I tried a gently sloping mound about 12” in diameter that built up just over the lip of the grate. I let it set up for several days uncovered in my garage in South Carolina summer heat. Temps never dropping below 90*. It looked great after drying with minimal shrinking and thin edge cracking. I then fired it slowly, building successively larger fires until finally running a fresh batch of green coal up to near welding heat. This worked for about a week. Then I noticed hairline cracks all over the clay and the entire thing crumbled when I tried to remove the coal for cleaning.

I know the suggested method is any found clay, sand, grog, and possibly fire clay. My main question is, will I ever be able to make a cone 6 clay mixture that will withstand these temps and hold this grate in place? I’d like to be able to build up a 4” thick “table” around the grate and then build in a sloping fire pot in the center that holds the grate centered. 

Right now, the clay is dissolved in a bucket of water to just above a slip consistency. I intend to mix with dry sand until I reach the preferred consistency of ‘clump and crumble’!

So sorry for the text wall. I just wanted to give as much detail as possible.

tl;dr: I have cone 6 pottery clay and I’m trying to make it work as rivet forge liner/shelf. Will this ever work as I hope?


Ok, have at me.

Thanks, Ben

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I mixed builders sand to act as grog into cone 6 pottery clay to shape the fire pot and hold in the grate on my home made forge. that was about ten years ago and it's still holding well. If I remember the mixture was about 3 sand to 1 clay. Made sure to wedge (need like bread dough) it well for a consistent mix. I built a wood fire without any air to fire it

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That sounds exactly like what I’m looking for! Do you happen to have a photo? Did you clay all the way across at an even thickness then forge the fire pot down into that or do a ducks nest type thing? If the former, about how thick should I go in order to form a pot below it? Either way, I think I might have enough to get me going! Thank you very, very much! 

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Sorry it took a while to clean and get a couple of pictures. The fire pot is a ducks nest about three inches deep from the hearth. Originality it was seven inches deep, which was too deep so I built up the bottom with the clay with a four inch layer of clay and set the grate (which I can lift out) in the clay.




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  • 2 weeks later...

So, I finally got the new mix in! I only had time enough to build a large ring around the fire grate which left about 3” between the ring and the wall of the forge. The ring is about 2 1/2” thick and 4”wide. I let dry for 4 days in varying weather, but never below 50*. It hardened up like cinder block! Then I fired it 3 times with wood and no air, making sure to cover the top of the clay for as even curing as possible. These all went perfectly with no cracking or spalling, nothing! I let it cool fully between firings to see if there was shrinking or cracking. Again, nothing. So, I took it  for its inaugural run and it worked beautifully! I made notches on two sides for tool/work pass-through to limit the chance of chipping. This all worked fine. Then, when it was time to shut down, I drug all the coal to the outside of the ring, which had an unintended benefit of killing the fire quickly! It was then I noticed, I had a lateral crack about halfway up the inside wall about 1/4 of the way around.

Is there any chance I can patch/cover this or would I just be wasting clay for the inevitable do-over?

IDF&C, Thank you for the Birthday condolences! (and all of your help)

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