Looking for people who use homemade refractory cement in their furnace.

[dragonorb13]

So,  I'm trying to find a recipe to make some homemade refractory cement to replace my old refractory plaster stuff, and I've found a few, all of which involve Portland Cement as their base. But I've also found a few places that unequivocally say not to use Portland Cement, because it will spald. But none of these explain if this is universally true, of if it's only true of straight portland cement.

So, I was hoping I might be able to find some people who use a similar recipe to what I've found, who can tell me how hot you can get it before you run in to issues. Mostly I just want to cast aluminum and forge iron, but my roommate and I had been talking about trying to cast copper and sliver jewelry, as well. Formula is as follows: 1.5 parts Portland cement + 2 parts Perlite + 2 parts silica sand + 2 parts fire clay

Thanks, guys!

[Frosty]

The recipe you listed is almost appropriate for a fire pit or fire place if you leave out the perlite. 

It WILL NOT last minutes at forging or copper melt temperature. It MIGHT survive aluminum temps but I wouldn't want to be within about 25' of it. 

Why do you want to make your own refractory? You can buy refractories that work, formulated by professionals. You might think spending a couple hundred dollars on a melter and forge sounds like a lot but you'll save money on fuel, repairs and potentially doctor and hospital bills. 

Also building one furnace to do two different things can be done but it won't do either very well. 

There is a large propane forge section here and the most current is "Forges 101." How to make a safe and efficient forge and liner is discussed at length. There are a number of casters aboard who can help you with building an efficient safe melter.

We enjoy helping folks get this stuff right so they have a good piece of equipment that's as safe as an inherently dangerous pursuit can be. 

 Frosty The Lucky.

[dragonorb13]

Exactly as you say, I didn't want to have to spend a couple hundred dollars just to get one bag of refractory cement. Le sigh.

[ThomasPowers]

So where in the state are you at?  A.P Green in Albuquerque is where most of the smiths I know get their refractories and at much better prices than you seem to be quoting.

There is also refractory companies in El Paso TX if you are down in the South.

If you are in the far north Colorado may be your best bet.

If you factor in your time using a professional refractory may be trivially cheap over making your own and replacing it over and over again.  If you are not factoring in your time---I have a 90' long 4' deep trench that needs to be dug, that I would gladly exchange a sack of refractory for!

[Frosty]

20 hours ago, dragonorb13 said:

one bag of refractory cement. Le sigh.

"Le sigh" . . . ? Nicely said, excellent turn of phrase. Pepe Le Pew's ever hopeful wanna be girl friend?

NO refractory cement, or mortar!! There's an important distinction. Mortars and cements are intended to glue bricks and stuff together and will NOT survive direct flame contact in a forge. Ask for "water setting castable refractory" look through the catalog and see if they have a "high alumia" version. If you mistakenly ask for a refractory cement or mortar that's what they'll give you. 

When you go into an outlet it's important to know the correct name for what you want or they'll sell you what you ask for.

If an outfit in the lower 48 is asking a couple HUNDRED dollars for a sack of refractory it's some specialty stuff go back to the catalog and look again. I paid $71 for a 55lb. sack of Kastolite 30li in Anchorage Alaska shipping included. If they carry Kastolite it's darned good stuff, I recommend it.

Frosty The Lucky.

[dragonorb13]

I actually moved a couple years ago, I'm in Alabama, in a little spit of nothing just outside of Dadeville. If I were still in NM, it'd be a little easier, I knew a few fireplace shops there that sold high temp fire bricks and such, and could probably get castable refractory.

Frosty. Thank you for that explicit differentiation. I did *not* know there was a difference, and I'm very happy my tired brain remembered to pop over here and check this thread while I was looking through stuff. Water setting castable refractory. Not that I'm going to pay this guy for it, but is this the *kind* of thing you're refering to? (I'm sure I can find it somewhere else, but 94% alumina seems like a good "high alumina") while I look for other things, your suggestion of kastolite among them.
Links to commercial sites is a violation of the TOS.

Edited June 29, 2020 by Mod30
Remove commercial link

[Frosty]

Sorry about the slow response, don't know how I missed your last post, I should've gotten a notice. 

None of those links works not now anyway. You looked on Etsy?  ETSEY?! That's kind of like looking in the personals isn't it? 

Please get off the computer and use the telephone. Look for a HVAC supply or service company and call them on the phone. No need to tell them what you're  making, just ask for a water setting high alumina castable refractory. Kastolite 30 li or the equivalent. Anything with a 30% or higher alumina content is plenty high enough. 

The only website your links pulled up was a large commercial supplier's front page. They want to sell by the ton so do NOT expect a response for small quantities like a sack. 

Frosty The Lucky.

[stevomiller]

I agree I think it’s penny wise and pound foolish to make refractories.

I was able to buy refractory once from an AP Green warehouse. They sold me a bag with a hole in it for half price.
 
Also ceramic wool is cheap, you can buy short pieces 2300-2600* 8lb density. Buy 5-10 lbs to hard face it from the IForgeIron store. If you plan to weld in it with Borax flux 90% plus alumina will last longer. 
 

$75 will insulate LPG bottle or smaller refrigerant bottle forge/furnace.

Edited to remove refractory sellers and inserted IForgeIron store. I haven’t been here for at least a year and didn’t know this site carried gorge building supplies.