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Gas forge and Kaowool coatings


CAE

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 I've been bitten by the Blacksmith bug and trying  to take my time and do it right the first time. That has been somewhat of a challenge. To satisfy both side of me I threw together a small paint can forge today while I put together a Frosty T Burner and a Propane tank forge. My first post was in the Introduction section and I had only one response to a couple questions I posted. Mr. Thomas Powers was kind enough to give me a little advice on a gas forge build. I've poured over so many post about gas forges I've lost count. I've built the Frosty T Burner and tested it in a stack of fire brick and I think I've got it tuned close enough till I get the PP tank forge body done. Mr. Powers suggested I used Kaowool for it's incredible efficiency. So I know Kaowool is readily available online in many places but I tried to find a local supplier for the no waiting aspect of buying getting it now. This is where it gets crazy. I stopped buy a local heating shop where I know the owner. Ask if he used the material and he does on occasion but doesn't stock it. He then matter of factually said why don't just go to _________ and ask for Lisa, tell her I sent you and she'll sell you some.The business he suggested is 3 miles down the road from his shop. Stop there and found Lisa, she said the 1" 2600* sells for $94 for I can't remember how many sq. ft. When I explained I was only looking for about 12 sq.ft. she ask if I could use scrap. Turns out I left with a full box of I don't know how many sq. ft. of 2'x 3' scarp pieces.(it weighs 45#) Unbelievable part is I only cost me $20. And that's only because I gave her the twenty to buy coffee and donuts for the whole 5 people that work there. She was going to give it to me FREE. So Tom Powers I'm going to build that PP Tank forge with Kaowool after all. Thanks for the suggestion or I would have never went looking for it. Next question. I know I've read many post about IR coatings for Kaowool as well as rigidizers. Do you need both? Looking at Wayne Coe's Plistx and Kast-O-Lite. Seems to be very cost effective and He's a member here.  

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CAE,

It seems to me that you have both good friends and good luck. Yes, you need both rigidizer and finish coatings. rigidizer is especially important for you because you won't be able to make single cut parts, and fit them against a curved wall under compression. So, if you want your insulation to last it must be completely rigidized. On the other hand, between using 2600 F insulation and rigidizer, you will toughen the secondary (inslulating) layer in your forges enough so that it should stand up well to the heat that will leak past the high emissive coating (AKA IR reflector) and thin hot-face layer (typically Kast-O-lite 3000):

(A) You don't want to use thick layers; instead of a single 2" thick layer, place the insulation in two 1" thick layers. Ceramic fiber blanket will easily part into thinner layers via delamination between layers.

(B) Rigidize each layer after installation, and heat cure it, before installing the next layer.

(C) Form  the burner openings before rigidizing each layer. For more specifics ask Frosty or one of the other members who use tapered openings or flame nozzles on/with their burners; I use step nozzles,and so can't properly advise you on this subject. But, remember to leave them just a little oversize so that they can be finish oated with a hot-face layer.

(D) Rigidizer is just fumed silica (which remains suspended in water) and common everyday food coloring (to allow you to visually judge how much to use); this water born product is easiest to dispense by spritzing. But, you can always pay though the nose for it from a pottery supply if you prefer ;)

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Just to clarify the PP Tank build and material I have. The Kaowool scraps are  1" x 2' x 3' pieces  I will have no problem cutting tops, bottoms without a splice. At 36" of usable material length it will be close on the sidewall wraps on a 20# PP Tank without splicing. If I do need to splice in a piece for the sidewalls I intend to alternate the splices putting the final interior layer splice on the bottom. My thought here was I'll be using a hard firebrick for the floor.minimizing any issues, since this splice will be covered. The way I read your advice Mike is, the rigidizer can take the place of the Plistix. Then coat the whole interior with Kas-O-Lite for the finish fire coat. Am I correct?

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Kaowool + Rigidizer + hot face + high emission coating.

 

I do kaowool, rigidizer, and a combined hot face/high emission coating.  If I were doing production work, I'd use the cast-o-lite 3000 as a separate hot face.  My combination is a mix of kaolin clay and zircopax.

The rigidizer does a number of things - 1) it cuts down on the kaowool from shedding under use (not good for the lungs) 2) it makes the fiber _rigid_ which means that your hot face/reflective layer won't flake off.  The hot face protects the kaowool, and the high emission coating improves the efficiency of the forge by reflecting all that lovely heat into the interior of the forge.

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CAE,

Don't use hard firebrick for the forge floor, 3/4" or even 1" thick high alumina kiln shelving is utterly superior to fire brick in strength, resistance to super heated fluxes, and blocking heat transfer. The average fire brick is roughly equivalent fire clay in heat transfer rates; high alumina is up to seven times more resistant to heat transfer. The only refractory substance more resistant to heat transfer is zirconium oxide. A kiln shelf can be cut long enough to extend through both ends of a steel forge shell, and because it is designed to carry heavy loads of pottery at very high heat (rated to support your load at 3000 F). Becuase it takes so little space, there is plenty of room between it and the shell to add ceramic blanket. which is quite springy before it "takes a set" after a few heat cycles. By cutting a 1/8" oversize rectangular slot for the shelf, you can stuff a lot of ceramic blanket under it, making a very good additional support for the forge floor, along its entire length; what more could you want for about $23 at your local pottery supply?

No; rigidizer is not anything like Plistex. Rigidizer is colloidal silica (AKA fumed silica). It penetrates through the ceramic blanket to strengthen it. Plistex is a hard finish coating, which is one way to seal the ceramic blanket and provide a smooth finish layer on which to paint a high-missive coating (AKA (IR reflector"). while Plistex is claimed to be an" effective IR reflector," any high-alumina castable refractory can match it.

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Go to the Forge Supplies page at www.WayneCoeArtistBlacksmith.com and study the attachments there.  For the Propane Bottle forge you should only need about 2' of the ceramic blanket, 4 5# bags of Kast-0-Lite and one pint of Plistix or Metrikote.  I suggest that you cast the floor with the ceramic blanket (to take up space) and cast over that.  I cast about 1/2" thick.

Let me know if I can help you.

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 Thanks Mike for clearing up my questions and Mr Coe.... I recently emailed you about the products you referred to in your post. I received your email  response  and will be sending you and order soon. Thanks to both of you. I've got a lot of irons in the fire so to speak. No pun intended cause I dont even have a fire at the moment LOL. The door to this whole metal world has just opened for me. Great friend of mine who's career was welding has given me an old Miller 90 amp Mig welder and a 1/2" plate for a welding table top (no legs yet.).... that's my first welding project, and given me a few lessons in welding. Second project-I've got going is a coffee can forge w home brew refractory curing, I've finished a Frosty T Burner and it's waiting for a forge to be mounted to and tuned. Third Project-Visited my local scrape yard and brought home a 30" x 30" x 6' angle iron stand that will become a coal fired forge someday, also found a brake drum and 20# of various bar and  round stock to mess with when I can get it hot enough. Can buy all the scrape  I want for 25 cents a #. Fourth Project- is the PP Tank Gas forge of which I have the blanket for. And believe it or not I found a 50# Vulcan Anvil locally that I've already mounted on several 4x6 post bolted together. It's small but in pretty good shape. Couldn't pass it up but I still want a bigger one.... 100# range..My garage kinda looks like a war zone/junk yard right now. Need to go work on something.

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Don't get so many projects going you can't finish one. Been there done that or failed to do that I guess.

Try not to incorporate everybody's advice at once. It's not contradictory but some doesn't work as well together as others and you need to have some experience to know which is what. Pick one set of advice to follow it'll be much easier. I keep changing or growing my forge construction opinion as I read this stuff. I've never built a forge I haven't redesigned as soon as it was finished.

Give me a shout if you have trouble with the burner, I got that one covered. ;)

Frosty The Lucky.

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Frosty I did just what you've suggested. I had the T Burner ready and just couldn't wait to pound something. So I made a quick paint can forge with a home brew refractory that isn't holding up too well. So quick I forgot to put the darn legs on it so I just rested it on solid fire brick. I managed to pound out a couple real funky looking leaves then I did a fair job on a coat hook with scrolled ends and one half of a pair of flat bit tongs out of 1/2" bar.Still working on that one. should have started with round cause thats a lot of square bar to pound round for the reins. Going to send off for the rest of what I need for coating the insulwool and may build another can forge  while I'm working on a larger PP tank forge just to have something to get hot. Pretty sure it's official I'm hooked 

IMG_0821.JPG

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