Instructables

Step 1: What do you need?

"Masonry cement" (on the left) is not the same as "Portland cement". Portland cement is plain cement powder and specifically says Portland cement.

Masonry cement is a mixture of Portland cement and sand. It may also contain other components (admixtures) to provide a certain characteristic such as waterproofing agents, colors etc. In some cases you only need to add water to masonry cement mixtures.

Fireclay is usually (at least where I buy it) sold in 50lbs (about 23kg) plain packages and they don't even say "fireclay" on them. I get it from a place that exclusively sells masonry supplies for $8.00 (2002 prices). I've never been to a ceramics supply place so I can't say whether or not they sell it. Whip out your phone book and call if your wondering, in fact maybe I'll do that.

Another type of clay is Bentonite clay. I haven't been able to find any where I'm at. I've read that it's available from feed stores and farm supply places. Kitty litter is bentonite clay. But unless you have a big rock tumbler or ball mill I don't expect anyone to use this source. Anyone willing to grind enough kitty litter by hand is a much more patient person them me. I've tried using it whole but it didn't work, however I think I might know a way.

Step 2: What Else?

Perlite is a light-weight odorless, sterilized, heat-expanded volcanic mineral. It's used in potting soil to loosen and aerate the soil resulting in strong, branched root development. This is vital to vegetable seedlings because... oh wait, we're talking about refractory...

The reason it's so good for refractory formulas is because it doesn't conduct heat very well (heat doesn't pass through readily). A similar product is called "vermiculite" it's added to potting soil because it retains moisture. This quality makes it undesirable for refractory.
 
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sparhawk76 months ago

kaolin clay is another alternative to bentonite or fireclay. firec;ay is a generic term and bentonite or kaolin may be labeled as such as well. that's the biggest trouble i've had is finding somewhere that carries it, as i would rather not pay 50 lbs shipping fees. if anyone else has other names they go by please let us all know! thanks for the instructable.

Try Home Depot it is only sold in the store however it is better than a 50 lbs. shipping fee

both lowes and home depot have it on their online stores, however they do not ship to store everywhere, don't know why. cat litter contains sodium bentonite(fireclay usually has calcium bentonite) the difference is in shrinkage. cat litter needs to be unscented clumping, and ground down, mix it with sand and perlite and it should be okay. fireclay is not exactly the same as bentonite, but usually contains bentonite or kaolinite clays. bentonite will not vitrify, so it can't be fired the same as fireclay. this means it will absorb water and swell and shrink as long as you use it. however, bentonite is preferred for your greensand investment, because of that. if you use fireclay it will vitrify aroung your piece and... well there you are. good luck to everyone!

Tredlock3 years ago
I believe you have the perlite and sand incorrectly labeled. Perlite is the white substance with what appears to be a larger particle size, while the sand is the fine brown substance.
jimcaro4 years ago
when you add the perlite is it powdered or just as you buy it from the store?
Nagarok jimcaro3 years ago
From what i can see in the picture, it's powdered.

But I'd imagine the stores would also sell it powdered, because it's used as a soil enhancer. I think..
Am I missing something here? Elaborate more please. How do I make the metal can it's in? Where does the heat come from? What is used to cover it? Too many questions to continue.
this was actually taken from Lionel oliver's backyard metal-casting website. the metal can is actually a bucket, this design is part of the two-"bucks" foundry which is illustrated on his site. the cover was actually intended to be a second bucket, thus the name two-bucks. the heat comes from whatever method you choose to use to heat it, whether that be charcoal, propane, or waste oil. by the way, waste oil (burners) has been popularized due to its relatively low cost compared to propane, it also produces a greater amount of heat.
I have heard some rumours about refractories being made in this way exploding because they are not 'rammed' properly. can any one please explain what this ramming process is? As far as I am aware, you just pour in the mixture, is there anything else you need to do?
Ramming, at its most basic, is when you take a flat bottomed stick and use it to compact the refractory. This eliminates air pockets that can heat up and expand explosively.
evoshendor5 years ago
I've just discovered that I can powder cat litter in a blender. I filled the jug about a third with the dry litter. Two minutes on high speed and presto...
Hey hows it going? Hey look i am making a furnace for myself, and i cannot find anyone or anywhere that supplies powder fireclay, how did you obtain it, thanks
Have you had a nosey on ebay thats where i got mine from I even got some stuff to make some thermite to kick start the heat process off. Just a teaspoon i thought!! but decided against that idea Well at least till i try it it on another container first lolPs guys and gals if you do use kaowool remember once it has been heated it is extremely bad for the lungs and health real nasty dust
ganister or flint clay are what you're probably going to be googling for. Upto around 1300F, ganister will resist spalling better than flintclay, but is usually more expensive too. and if you're doing iron work, you'll easily exceed those tempatures. If you want to stick with local suppliers, you can get away with using straight kaolin for your clay additive, and a ground up featherrock(landscaping item... check any of the big box sotres) as your "fluffer material". Don't forget your protective masks when mixing your cement batches. This stuff WILL get in your lungs, and harden. And once you have a cement lump in your lungs, it's there forever(unless you get a lung transplant... UGH!) As my neighbor Bernie can attest, it's a survivable condition, but he's on oxygen almost ful time, and most of that is spent in a wheelchair, on account of not being able to breath well enough to walk, most of the time.
Ceramic supply, sometimes masons/bricklayers (for fireplaces).
just copy and paste. very nice