Soup can forge?

[Soldierz]

[John McPherson]

In a word: NO. Plaster of paris will hold moisture and the trapped vapor will cause cracks at best, and violent steam explosions with shrapnel at worst.

 

For a small or large can forge using propane you still need real ceramic fiber batts and real refractory cement or similar lining to contain the ceramic fibers.

 

For an ultra-small, easy forge, one or two soft firebricks from a potters supply will work with a plumbers torch. Hard masonry bricks are not the same, soft firebricks can be carved with a spoon, and weigh only a few ounces.

[Dodge]

I second the "NO" vote on PoP as well as the hard masonry bricks. Doing cheap can cost big time in the end. Definitive word here: End!

[brimic]

I wouldn't bother. Plaster frightens me, especially if its green.  

I do lead casting - bullets, sinkers, jigs, etc... you can't or shouldn't use plaster for the reasons mentioned above for lead and that's only going up to 800 degrees max. I've made moulds using a product called 'water putty' which dries similar to plaster, and has to be heated to 400 degrees for a few hours to drive the water out. It worked for casting lead, but the moulds themselves burn up fairly quickly and would absolutely not be suitable for a forge. Like I said, don't bother.

 

My first gas forge I made was with a paint can, lined with 3" of refractory wool coated with ITC 100, and powered by a bernzomatic torch that I adapted to a grill tank. It gets HOT, but only heats about 3" of steel at a time.Materials don't cost me much, we have a refractory supplier in town and the salesman was able to sell me scraps and leftovers for cheap.  Fun experiment, but if I were to do it all over, I'd build something bigger with the Reil-style burners (which I'm currently working on).

[Nobody Special]

Maybe bad chemistry, but I think (LONG time since chemistry and haven't played with plaster) gypsum, aka calcium hydroxide (plaster) heated enough turns to calcium carbonate, (like in cement) then calcium oxide (quicklime) which is both caustic, and tends to ignite spontaneously when exposed to water.

 

Also remember that if you do anything with plaster of paris, it releases a lot of heat as it sets and you can get burned. You hear news stories occaisionally of it happening when someone tries to make a casting of someones hands or a homemade cast for a broken bone.

 

If you want to go cheap on refractory, why not clay, or clay and sand, or fireclay and sand, or the cheapy refractory recipe on backyardmetalcasters, or firebrick, or furnace cement, or a dirt hole in da ground.............