Pouring a Forge liner question ?????

B . Buxton

B . Buxton

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Jul 8, 2001
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I've always used a kaowool forge with satinite brushed on and I'm tired of needing to replace the wool everytime the flux gets thru it. So I figured I would build one with a castable refactory liner about 1" thick, I figured that should save a bunch of headaches by better wool protection. How do you guys cast the liner outside the forge body? and what would be the best refactory for this. Mizzou or insulated kastolite? I've never used it so Can you thin this stuff down enough to pour down a 1" opening?

Thanks guys

Bill
 
Watching the thread, waiting for someone to say that you need to open the forge up to be able to pour it inside the forge. Wax-paper around inner mold as a release agent. I was planning on using vermiculite and mortar. We'll see how it goes.
 
Thanks for the reply, I figured a pipe inside a pipe (5" inside a 7") then pour refactory in between the 2, but I didn't know if you could thin this stuff down that much and it not lose its ability to do its job. also which refactory would be most recommended for best performance and endurance. Maybe someone with some first hand experience will chime in.

Thanks again

Bill
 
I have used gas forges with kaowool, and one with cast refractory. I like the kaowool better because it heats up a lot faster than the cast refractory. If I tried to heat the cast refractory too fast it would crack. Now if you are going to forge all day the cast refractory is the way to go.
 
It's a trade off. I've had forges with too little thermal mass, and forges with way too much.

My current ribbon burner forge for doing damascus is 24" deep, has about half an inch of refractory over 2" of ceramic fiber, and 6 extreme duty ultra high alumina firebrick for a floor. It's extremely efficient for forging all day long, especially 2-3 billets at a time. *However* it takes 45mins+ to reach 2300+ and stabilize.

Once it's there and stable, the rebound times are amazing, and it sips fuel. However, it's extremely wasteful to crank and forge a blade or simply do a single restack. If I'm not running it for atleast a few hours it's a waste compared to running my smaller vertical welding forge.




As to your specific questions Bill: You definitely should still use ceramic fiber around the cast shell. I'd also recommend using an insulating castable like Kast-o-lite. However, flux will still tear this up. If you don't use an insulating castable, and you don't use ceramic fiber, expect extremely poor fuel efficiency, and a forge that will catch things in the vicinity on fire.


If all you want to do is add durability, stick with using ceramic fiber (2" of the high temp stuff atleast, more is always better if you've got the space), pour a 3/8 or 1/4" liner instead of smearing, using kast-o-lite or mizzuo. IMHO Mizzou is more flux resistant than kast-o-lite but less insulating. Not an issue if you insulate with ceramic fiber. I also recommend looking into Kiln washes for salt kilns. Potters use them for the kilns they throw "fluxes" into to get glaze effects. A serious kiln builder buddy of mine mixed some up for me (but they're available retail) and I occasionally coat the floor of my large horizontal and the flux just scrapes off without harming anything.

A cast liner around the ceramic fiber will be *much* more durable and flux resistant than smeared on satanite. Best option is to use a paperboard tube or form after you put the ceramic fiber inside. Worst case you can burn it off outside if you can remove it.
 
Line the bottom of your forge with bubble alumina coating. The Kaowool lined forge will make up its initial cost with efficiency rather quickly. Or bricks like Javand mentioned.

If you're going to be doing mostly billets, consider a vertical forge with a kitty litter floor... Most efficient for that type of work IMO.
 
Thanks guys, I appreciate your comments. any other comments from others that have great success with forge building would be welcome.

Bill
 
I made a horizontal forge once where the bottom third of the circumference was castable, and the upper two thirds was kaowool. It heated up faster and the lining lasted longer since flux falls down. I suppose you could do something similar with a vertical forge, but I haven't tried it yet.
 
Not very helpful, but personally I prefer the fast heat of a 2" kaowool liner over the benefits of a castable liner. I've had a couple forges with castable, don't like the thermal mass effect. I find Kaowool easy enough to replace once a year.5 or so.
But, no doubt your experience rests on a good deal of complicated pattern welding and more forge time than I've put in.
So, have you considered moving away from the use of borax? Kerosene, or no flux at all?
 
I have three vertical forges with 2" wool, coated with Satanite and three inch clay cat litter floors.
I just did a little bit of Satanite patch work on the walls of my major Damascus-making forge this past week and before that I'm pretty sure I haven't touched that one in over a year.
The little amount of work I find necessary on my forges to keep them running efficiently is so minimal I can't think of doing them any other way.
I get a little bit of damage right around the entry door, but it's so little it hardly bothers me.
I bought one bag of Satanite in '03 when I built my first vertical forge and I still have about 25% of it after building and maintaining three forges.
And that includes the clay I've used on "MANY" knives with hamons.
 
Thanks guys,

Salem, I do a lot of kerosene and dry welding, but when I'm making a billet that needs several manipulations I don't like waiting for it to cool between welding heats so I flux them up
after the first welding session.
I've made horizontal and vertical forges and I get much better heat out of a horizontal, smaller diameter chamber plus a longer chamber so I can work a longer bar at a time welding and forging. There's no right or wrong with what forge type a person uses, it depends more on what your wanting to do with it. I'll probably stay with kaowool/satanite but there should be a way to make one a lot more durable and not have to compromise much.
Does anyone know much about the kastolite refactory, does it how up well against flux better then satanite?
 
It's not a magic bullet, but using a goodly amount of rigidizer on the kaowool seems to help a lot.

I use a very runny mixture of porcelain powder and either proprietary rigidizer or a homemade version, which is Sodium Silicate dissolved in water. Slathered onto the kaowool, the rigidizer penetrates a good inch or so, while the clay powder only gets in perhaps 1/8" or so and seals the surface. With subsequent (less runny) coats, penetration is minimal and a surface layer builds up. I usually make the last coat 2 parts Zircopax to one part porcelain powder in plain water, in the hope that it will give some IR reflective properties.

Once fired, the thin hard shell over rigidized kaowool seems much more durable than a similar hard shell over unrigidized kaowool, at least in terms of resistance to knocks.

I'm in the UK and Satanite is not available here. I'm guessing it would work the same as the porcelain powder.
 
B . Buxton said:
Thanks guys,

Salem, I do a lot of kerosene and dry welding, but when I'm making a billet that needs several manipulations I don't like waiting for it to cool between welding heats so I flux them up
after the first welding session.
I've made horizontal and vertical forges and I get much better heat out of a horizontal, smaller diameter chamber plus a longer chamber so I can work a longer bar at a time welding and forging. There's no right or wrong with what forge type a person uses, it depends more on what your wanting to do with it. I'll probably stay with kaowool/satanite but there should be a way to make one a lot more durable and not have to compromise much.
Does anyone know much about the kastolite refactory, does it how up well against flux better then satanite?
Click to expand...



I mentioned kast-o-lite in my post above Bill. It's more durable than satanite, but not as durable as mizzuo when it comes to flux. Thin "smeared" sections will break off just like satanite if you smack it with a billet, especially around openings.

I recommend keeping a bucket of some pre-mixed refractory like APG's Greenpatch to fix damage as it occurs (i.e. smear it on when you're done forging and the forge is cool enough to get close to).

I also use a horizontal forge because I need the capacity to heat an entire long billet when using my rolling mill. I also can't keep a "handle" welded on to the end like most do with verticals for the same reason.



There are a lot of options to increase durability. Poured refractory is generally more durable than "smeared" because of the uniformity in thickness and smoother surface, however it's generally a good idea to use something like split high alumina bricks, kiln shelves, etc, around high wear areas such as openings, etc, the trick is not adding too much thermal mass that you need long times to get to temp if you're only forging for a couple hours at a time.
 
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