I have some extra refractory cement laying around. Can I use that for a gallon paint can forge, or should I go out and buy some plaster of paris and sand? I'd just do it, but the cement says that it shouldn't be thicker than 1/8th of an inch. It'll be closer to two inches when if I use it and I'm wondering if it might shrink and crack.
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Paint can forge question
- Thread starter jweber
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Do not faff about with homebrew "refractory" you have seen on Youtube.
Be sceptical. If someone shows a forge they have built being used to forge its 30th knife, then by all means sit up and take notice.
If you see a freshly built forge that appears to get hot enough, but has no follow-up showing subsequent uses, ask yourself why this might be?
You can buy Refractory Ceramic Fiber blanket in small quantities online and it is reasonably cheap and easy to ship. It insulates well and has little thermal mass. A double layer of blanket in a coffee can forge will make a much better forge than any homebrewed lining material.
The RCF blanket tends to shed fibers when you poke it with your workpiece and these are generally considered a health hazard. You can use the refractory cement you already have to immobilize the fibres and make the surface more durable by applying a wash of the cement diluted with water so that it soaks in well. When I did it, I found that I got a reasonably rigid layer about 3/8" to 1/2" thick. Once it is dry, you can apply a second coat with minimal added water to give a 1/8" shell on top.
If the cement has stood for a long time in the tub, there will be a fairly thick goopy liquid on the top. I try to use as much of this in the wash as I can: it seems to do the rigidizing thing best that way.
Be sceptical. If someone shows a forge they have built being used to forge its 30th knife, then by all means sit up and take notice.
If you see a freshly built forge that appears to get hot enough, but has no follow-up showing subsequent uses, ask yourself why this might be?
You can buy Refractory Ceramic Fiber blanket in small quantities online and it is reasonably cheap and easy to ship. It insulates well and has little thermal mass. A double layer of blanket in a coffee can forge will make a much better forge than any homebrewed lining material.
The RCF blanket tends to shed fibers when you poke it with your workpiece and these are generally considered a health hazard. You can use the refractory cement you already have to immobilize the fibres and make the surface more durable by applying a wash of the cement diluted with water so that it soaks in well. When I did it, I found that I got a reasonably rigid layer about 3/8" to 1/2" thick. Once it is dry, you can apply a second coat with minimal added water to give a 1/8" shell on top.
If the cement has stood for a long time in the tub, there will be a fairly thick goopy liquid on the top. I try to use as much of this in the wash as I can: it seems to do the rigidizing thing best that way.
Stacy E. Apelt - Bladesmith
ilmarinen - MODERATOR
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Look in the stickys and read about making a forge. It needs a insulating blanket ( Inswool) and a refractory coating over that ( satanite). Making a tiny paint can forge will usually be a waste of time, as you will almost immediately realize that it is too small. Make a small forge about 6" by 12" and you will be much happier.
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I made a paint can forge just for heat treating knives. It got me started, but it was one blade at a time. Plaster of paris and sand is not the way to go. It is a terrible insulator. I used perlite and thinned out furnace cement at a 4/1 ratio. It worked well and i was able to get a feel for what a blade should look like at temp. If you already have a torch and paint can, it really isnt much time or cost to make one. It's on par with a 2 brick forge in my opinion. NOT for actual forging.
What did you dilute the cement with? Water?
I'm just trying to heat treat my first home made blade. If I end up enjoying it enough I'll go bigger. I did also order some ceramic cloth.
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Water. You want it like melted ice cream. Just wet enough that you can mix 4 parts perlite to 1 part thinned cement. Once you have cast it, it will take a good while to dry. You can speed the process by keeping it warm and dry.