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refractory cement


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I'm looking at purchasing some fireplace refractery cement form a local supplier, it says it can go to 2700 degrees, will that work or will my forge get hotter than that?

Im building one out of an old freon tank with 1in Kaowool and one burner possibly two if it doesnt get to welding heat with one.

I'm hoping to buy local to avoid shipping charges...

 

Thanks!

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First off, where is local? 

 

Kaowool is rated at 2400*F, another source says 2300*F

Mild steel is said to melt at 2372*F   Steel is said to melt at 2786*F

 

The maximum temperature of a coal fire in a forge is about 3,500°F and coal gas burns at about 3,590°F.

Propane can reach as hot as as 2820 C or 5108 F

 

Your build, you set the specs, so it is your call.

Be sure and let us know how it turns out.

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Welcome aboard Redbeard guy, glad to have you. Put your general  location in the header and you might be happy to discover how many of the IFI gang are within visiting distance.

 

If you're using Kaowool I have to assume you're making a gas forge. If so you probably don't need or WANT cement of any kind. The natural rebound of Kaowool when compressed is more than enough to keep it in a cylindrical forge shell.

 

If you're looking for a coating to protect the Kaowool, Google "Kiln Wash". ITC-100 is one of the best known of those used in propane forges but it's gotten so expensive most of us look elsewhere. You can mix your own version using "zirconium silicate" and Kaolin clay for way-WAY less $. Recipes have been posted here more than once. I use my home brew and it works a treat.

 

Frosty The Lucky.

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ITC100 is a paint, basically, and has no strength or rigidity.  If you put it directly over Kaowool, you'll poke through it every time you grab your steel out of the forge.  Think of it like the shell of a hard-boiled egg, except that it's not as strong as the egg's shell.

 

Castable insulation is strong, durable stuff (relatively), but it's not that great of an insulator and you'll spend gobs of fuel if that's your only insulator.  So, most folks will line their forges with batt insulation like Kaowool and then coat said wool with a quarter-inch or so of castable.  This is then painted with ITC100, Plistix or Metrakote.  By combining the three, you get all the strengths and minimize all the weaknesses.

 

The castable insulation isn't needed so much on the top or sides of the forge, but it's definitely a plus on the bottom where your work is always rubbing and bumping.  Wayne Coe, an IFI member, sells all the stuff you need on his website and has some great info on building forges.  Definitely recommend you look him up.

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Back when I used to make steel in 200 ton batches, we would tap stainless out of the furnace around 2650 and the fancy alloys around 3000.  In both cases there was all kinds of supper heat in the steel to allow us to pour it.  The alloy steels 4140 or 8620 for example were actually run into a second ladle that was housed in a vacum tank so it had to be much hotter for the extra handling.  So 2700 should be fine.

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I suggest that you cast the floor.  The hard fire brick is a heat sink and the soft brick won't hold up to the heat inside the forge.  The soft ones serve good as doors and a place to put hot iron on.  As my tutorial indicates, I suggest that you cast all the way around over 1" of blanket then paint the Plistix or Metrikote over the casting.  I believe that the main difference between the three IR products is that ITC-100 is about $75.00 a pint, Plistix is $10.00 a pint and Metrikote is $15.00 per pint.

 

As was mentioned earlier the IR products have not strength and every time you touch the wall, floor or roof you will poke a hole in it.  If you will cast with Kast-0-Lite over the blanket then paint over that with Plistix or Metrikote you will get a good, long lasting, efficient forge.  Otherwise expect to spend more time repairing than you do forging.

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Should have read your tutorial before doing my second forge. I got most of it right. Used stuff not kaowool but something similar I got off a glass smelting guy/blacksmith. 2" thick so used that, coated with castable refractory (forgot which kind) that i got from a nearby pottery place. Coated that with ITC100. This worked great for about 8months. I had some firebrick in the floor and it was pretty much a piece of glass from experimenting with damascus. I redid these by basically casting in new bricks. Probably should have just went with the castable. 

 

Still does pretty good just takes a little while to get up to heat. Holds 2000f consistantely while forging and I can ramp it up to 2350F pretty easy.

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Wayne's site has solid info no question. ITC or other kiln washes add very little strength. they do well to encapsulate the fibers to mitigate the breathing hazard. I do have Kaowool protected by only my home brew kiln wash but students are always beating heck out of it.

 

Castable or rammable refractories make far better inner liners. My first gs forge is still tough as concrete and it's a good 15 years old but you can no longer get the hard refractory, Pyramid went out of business some years ago. There are however other makers of high phosphate or phosphate bonded refractories. Phosphate refractories are generally used where caustics are present in the furnace and molten borax or most other fluxes are caustic as all gitout at welding heat.

 

I have split 3,000f hard fire brick as a floor in my forge because it is easy to replace. The soft insulating bricks I use as the walls suck, they do NOT like thermal shock so tend to break up after only a few hot/cool cycles. Next time I'm in Anchorage I want to stop by EJ Bartells and see  what they have for castable/rammables. that's in my wannado list so I'll let you k now if I can find a darned round toit when I'm in the city.

 

Anyway, a little armor over the insulation is almost a must, especially if you don't baby it carefully.

 

Frosty The Lucky.

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Frosty, I can ship you castable refractory in Flat Rate Boxes at reasonable shipping rates, even if you are in Alaska.

Let me know if I can help you.

 

Thanks Wayne but it's not necessary. The local EJ Bartells is only about 50 miles from here in Anchorage and they carry or will happily get virtually any refractory a person may need. I won't go on about the company, they don't advertise here and I don't want to cross the line and get their very name blocked. Heck, next time I'm in town I'll have to suggest it to them.

 

The local guys are INTO controlled fire, love to brainstorm with a fellow and have a pretty BIG library of tech books. Gave our organization (I use THAT term loosely. <grin>) a serious discount without asking, frequently give me product samples to test and "scraps" from their installations. The last time I talked to the guys they didn't carry kiln washes though, not an application in their type of furnace.

 

WE buy Zircopax (zirconium silicate flour) and flat rate shipping included it ran to $3.73/lb. Kaolin clay is more expensive but all told it's a small fraction of what ITC-100 costs.

 

Frosty The Lucky.

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