Hard Brick forge castable coatings?

[cjweaver13]

Good morning all, I am making a 6 brick hard fire brick forge with single venturi burner that will be able to run at max 20psi. The hard brick is all I have access to for the immediate future to hammer on some steel, and have read conflicting advice on coatings. Assuming no kaowool liner, would itc-100 or some rectory cement increase efficiency enough to reach forge weld temps? ...Or should I leave everything as is knowing it'll be enough to heat steel to hammer out and reach critical temperatures for heat treat, then build something more efficient when I outgrow this one.

 

[Randy3000]

What part of the world do you live where you cant get firebrick or ceramic wool? I started out with a lousy forge and i can tell you once i built a proper a setup i kicked myself for not doing it sooner.

Soft brick works so well due to air pockets. Cement by it self lacks air pockets.

 

[cjweaver13]

What part of the world do you live where you cant get firebrick or ceramic wool? I started out with a lousy forge and i can tell you once i built a proper a setup i kicked myself for not doing it sooner.

Soft brick works so well due to air pockets. Cement by it self lacks air pockets.

I have access to wool but don't want to use it yet because quite frankly I don't want to take the time to properly rigidize and coat it (blunt honesty). I can order soft brick for about $15 a brick, which is overkill with some current financial restraints (hence why I said immediate future). I live in the middle of nowhere NYS and in within a 3 hour drive nobody including pottery suppliers sell soft brick and seem unwilling to order it for me so here I am lol. Just want to make due with my current limitations, which I acknowledge there are some, for the time being.

 

[kuraki]

So, you want to build a forge that won't hold heat, and are hoping there's a coating that would take a day or so to apply and cure to help it hold heat, but you're not willing to use the stuff you have access to that will actually hold heat because you don't want to take a day to coat it and cure it?

 

[Stacy E. Apelt - Bladesmith]

A hard brick forge would be a radiant heat source for the room it is in, but it would be a lousy forge inside it.
If you use soft insulating firebrick, it will work. A coat of satanite and ITC100 would be OK inside the soft brick, but Charles at Atlas Forge has tested the difference and says it doesn't add enough to be worth the cost. He says to just use the soft K26 firebrick alone. A coat of satanite or similar refractory on the chamber floor is a good idea to give the forge a longer life.

 

[cjweaver13]

A hard brick forge would be a radiant heat source for the room it is in, but it would be a lousy forge inside it.
If you use soft insulating firebrick, it will work. A coat of satanite and ITC100 would be OK inside the soft brick, but Charles at Atlas Forge has tested the difference and says it doesn't add enough to be worth the cost. He says to just use the soft K26 firebrick alone. A coat of satanite or similar refractory on the chamber floor is a good idea to give the forge a longer life.

Is there a difference between the KC26 ceramic vs a generic cement hard brick, or is it just semantics? My local hardware store has the following...

http://www.acehardware.com/product/...rvgtsdscEsv8QZZyWxQBvwaKfax5m9S8aAtNBEALw_wcB

 

[cjweaver13]

So, you want to build a forge that won't hold heat, and are hoping there's a coating that would take a day or so to apply and cure to help it hold heat, but you're not willing to use the stuff you have access to that will actually hold heat because you don't want to take a day to coat it and cure it?

I really don't want to be a douche but this was not helpful, as I already flat out said I acknowledge the downfall of not choosing this for the time being. You're right, it will work better based on many many threads I've read. If I'm going to go this route I'll actually try cutting an old 20lb propane tank and make one using wool. FOR NOW I am choosing a different route for my current situation in both time and money. Thanks for the reply though and I mean that genuinely as this forum is very helpful.

 

[kuraki]

I'm not trying to be a dick. But encouraging you to proceed with wasting your time and money is contrary to your stated goals.

 

[Tenebr0s]

If you're looking to make a quick and dirty forge with hard firebrick to use until you have time to build a better one, why not use the firebrick to make a solid fuel forge? Lump charcoal will work in it.

 

[cjweaver13]

If you're looking to make a quick and dirty forge with hard firebrick to use until you have time to build a better one, why not use the firebrick to make a solid fuel forge? Lump charcoal will work in it.

Good point. I think partially because I already made a burner so just mentally locked myself into that idea.

 

[cjweaver13]

I'm not trying to be a dick. But encouraging you to proceed with wasting your time and money is contrary to your stated goals.

If I don't plan on forge welding, will this create enough heat, or is it still pushing the temp limits if I have a goal of being able to hold about 1600*F

PS. I checked out your website, and I like the handle materials you are using...some beautiful knives

 

[kuraki]

If I don't plan on forge welding, will this create enough heat, or is it still pushing the temp limits if I have a goal of being able to hold about 1600*F

PS. I checked out your website, and I like the handle materials you are using...some beautiful knives

That's hard to say without knowing the size of your burner. Maybe. Probably directly under the burner.

Thank you.

 

[KnuckleDownKnives]

You can order a much better suited brick for about the same price from ebay. I wouldn't use hard brick.

 

[joedhiggins]

I really don't want to be a douche but this was not helpful, as I already flat out said I acknowledge the downfall of not choosing this for the time being. You're right, it will work better based on many many threads I've read. If I'm going to go this route I'll actually try cutting an old 20lb propane tank and make one using wool. FOR NOW I am choosing a different route for my current situation in both time and money. Thanks for the reply though and I mean that genuinely as this forum is very helpful.

So here is the deal. Hard brick was designed to get and stay hot, radiating out that heat. It is not designed as insulation. I can get into the thermo math on this later if you would like, but the critical factor in all of this is "thermal transmittance or thermal conductivity," a measure of how effectively a material resists or conducts thermal energy through its thickness. Basically, hard firebrick is an order of magnitude more conductive than IFB. What this means specifically is that the hard firebrick will basically pass 10X the heat energy from one side of the brick to the other. At forge welding temps my forge (which is IFB and Insulwool lined) gets pretty warm on the outside. Water will flash boil if it touches the outside after holding temp for a while. With a hard brick lined enclosure, your heat loss would be such that not only would the exterior of the forge start falling apart, you would not reach forge welding temps without an insane burner setup (venturi at 20psi just ain't gonna do it). If you did, the outside of your enclosure would be darn close to forge welding temp too, and you would probably start melting gas lines and having your burner clamps fail.

Essentially, the design you are suggesting is not much more efficient thermally than if you were to just build a steel enclosure and use no insulation.

 

[Tenebr0s]

If you are set on using the hard firebrick you have, then a solid fuel forge is the way to go. I have been using a solid fuel forge made with hard firebrick for years, and it easily reaches forge welding temperatures. This will be dependent on your blower, not the material the forge is made from (solid fuel forges are quite different from propane in this respect - even a hole in the ground can work as a solid fuel forge).

*On the other hand, you can get 6 soft insulating firebricks on Amazon for about $20.

 

[joedhiggins]

If you are set on using the hard firebrick you have, then a solid fuel forge is the way to go. I have been using a solid fuel forge made with hard firebrick for years, and it easily reaches forge welding temperatures. This will be dependent on your blower, not the material the forge is made from (solid fuel forges are quite different from propane in this respect - even a hole in the ground can work as a solid fuel forge).

This is correct. The solid fuel itself serves as refractory. There is no need for external refractory. Forge welding can also be a bit easier with a solid fuel forge (though once you get it down, it works great in propane) for several reasons. It is very easy to run a reducing or neutral atmo in a coal forge and coal burns a good deal hotter than propane (which is good, but also means it is way easier to burn steel). Moreover, you dont have to worry about what the most flux resistant linging for your forge is, as the coal itself serves as your flux resistant lining.

 

[JTknives]

The amount of fuel you would need to pump into a hard brick forge to reach welding temps would be more then the cost of good K23 bricks. Using hard fireplace bricks is about equivalent to making a forge out of steel and lining it with house bricks and trying to heat it with a gas burner. Basically what you are making is a gas stove. The reasion the hard bricks are used in wood stoves and such things is becaus thy handle the temp much better then stright steel. But thy are designed to conduct the heat to the outside steel shell. If not then you would not heat your house.

 

[skillgannon]

Just out of curiosity, would wrapping hard brick with kao wool help?

 

[KnuckleDownKnives]

Just out of curiosity, would wrapping hard brick with kao wool help?

No, you'd be better off lining the hard brick with kaowool.

You're goal is to reflect as much heat as possible back into the chamber, not absorb it. however in either case you need to be able to withstand it.

 

[joedhiggins]

Just out of curiosity, would wrapping hard brick with kao wool help?

Absolutely, but it would take longer to get to temp than if you just eliminated the hard brick (cause you have to heat the bricks). Additionally, unless you are using k30 or similar HFBs, most of the stove bricks will decompose after a few firings. If you really want to use HFBs in a forge, leave enough room inside the insulated chamber to layer HFBs as a forge floor. My larger forge uses a layer of inswool on 3 sides, 2 layers on the bottom. Inside of the inswool are IFBs on the top and sides, and k30s on the bottom. K30s have a better R value than fireplace bricks, so provide some (but not much) insulation. Thus I doubled up on the kaowool under them. The bottom of the forge doesn't seem to get significantly hotter than the sides.

JT is absolutely right here. A large enough burner might be constructed to get a hard brick forge to welding temps, but the gas consumption would be insane. And not only would said forge fall apart after a use or two, you wouldn't be able to use it.

I built a blown burner fed by a 630CFM bounce house blower. It probably produces enough heat at full grunt, but you cant actually run it at full grunt and use it as the amount of superheated air coming from the forge mouth will burn off your hair if you get within 6 feet or so. I dropped to a lower px regulator after my initial firing test (outside of course) just to make sure that it couldn't run anywhere near full chooch.