Need forge advice...

I'm building a gas forge out of an old propane cylinder.
The cylinder is about 12" in diameter and I have cut 8" holes
in each end. I would like to line the cylinder with 2" of Kaowool, painted with ITC-100 and then put in an 8" wide section of 1" thick kiln shelf. The shelf will stick out each end a bit.
Seattle Pottery Supply has 1" thick cerablanket in 4, 6, or 8 pounds per square foot. Which density is best for my application? The Anvilfire store sells the 6 lb stuff so that would be my default unless there is a compelling reason to go lighter or heavier. Any one care to chime in on which weight would be best?
Also, there are a variety of kiln shelf materials available. I'm looking for something that is durable and can withstand being blasted by a 3/4" T-Rex burner. Mullite, silicon carbide, and high alumina shelves are available. I have found references that high alumina would probably be suitable and that mullite would not be as good. Not sure about SiC. Can some one enlighten me as to the properties of each material?
Thanks for helping a neophyte out--I'll probably have more questions as this project progresses.
Cheers,
Jeff Dantzler Seattle, WA
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Jeff, I live in the Seattle area too and I'm making the same forge you are. There's a guy selling some stuff you may be interested in: http://seattle.craigslist.org/for/59613254.html
You should email me offline, maybe we can help each other out a little.
To email me see http://www.tinyisland.com/email.html
do NOT reply to this email address as it's in no way real
Grant Erwin Kirkland, Washington
Jeff Dantzler wrote:

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No stinkin way. ;) What is it secret? ;)
Right here. Do it right here in-front-of everyone, ok? ;)

Grant, you work for Costco by any chance? ;)

Good questions and I want to hear the answers too, see? :)
Alvin in AZ
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snipped-for-privacy@XX.com wrote:

OK, Alvin, calm down. I figured maybe we could work on our forges together and do joint buys on things, maybe split a kiln shelf, stuff like that. Also, I wanted to ask him if he's working out of the Mike Porter book and I wanted to tell him that Mike Porter's local, a nice guy, and willing to help.
GWE

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Well alright in that case... ;)
Designing and materials discussions would be perfect right here tho right? ;)
Alvin in AZ (and only has an over-veiw of the process)
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You can save some money by using Kaowool rather than Cerablanket. Kaowool has a lower working temperature but the ITC-100 will make up for it. Higher density is better because it is tougher. But there is also the trade off with price. ITC-100 will help protect the fiber both from heat and abrasion. In fact, most of the wear you will see in a forge will be from abrasion or worse yet flux. Flux will eat right through it.
One-inch thick kiln shelf is huge. Keep in mind that you have to heat up the kiln shelf every time you fire up the forge. I would go with a thinner kiln shelf coated with ITC-100. This way when you drop a heavy piece of steel on the shelf and crack it, it will be cheaper to replace. Kiln shelf isn't made to be used in a forge. It will break and will require replacement. Design it to be easily replaceable. You can also use a lower grade of kiln shelf if you coat it with ITC-100.
You might want to check out ITC-200 for coating the opening of the forge to reduce wear. You might want to try your forge for a while before using this to see if you need it and to see if you like your design.
Since Grant is building a forge maybe the three of us could split an order of ITC-100 and/or other products. Buying in bulk can reduce costs considerably.
Keep in touch,
Kelley
On Wed, 16 Feb 2005 03:05:32 -0000, Jeff Dantzler

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In fact, I'm building two forges, one for me and one to sell to help cover costs.
GWE
Kelley Mascher wrote:

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The local place stocks the cerablanket and it should only cost about $20 for the insulation so no big deal there.

Thanks. This is exactly the kind of info I'm looking for. I'll go with the 8 pound per square foot material. My impression is that the stuff will just press into place and will stay once it's painted with ITC-100. Is there a need to use ridgidizer?

I'm still very curious about the different kiln shelf materials. A 12" x 24" x 1" piece costs $38.75 for mullite, $42.50 for high alumina, and $89.50 for silicon carbide. They also have recrystalized silicon carbide that is very expensive. Thinner shelves are available and the smaller (but still useful) sizes of mullite are much cheaper.
What are the properties of these materials? Would one be significantly more durable?

Suggestion noted.

I'd be happy to go in on some materials with local folks.
I should also add a link to a page that inspired this particular forge design. He is another local Seattlite.
http://www.cyphertext.net/~gfish/forge.html
I'll email him and beg him to put his images back up.
Cheers,
Jeff Dantzler (mylastnameinlowercase) at d r i z z l e dot com
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Hey Guy's, I have learned a lot about furnace construction from my glass blowing friends. Many of their construction methods adapt well to gas forges. What they call "glory holes" are very similar to what we use as forges. Any way. For the cost of one piece of kiln shelf you can get a box of ram-able refractory. This is a pre mixed high alumina, high temp. clay that can be shaped anyway you like. It can be fired in place. You can make it any thickness you want. It's tough as nails and impervious to flux and fire scale. I think an 80 lb. box is around $50.00. The only draw back is that on it's first firing it emits a sulfur like stench until it fully cures. this is more an annoyance than anything else. One box will make a LOT of forge floors or any other parts you want to toughen up. Another option is the use of light weight castable refractory. One trade name is "Kast-o-lite 30" This stuff is not as tough as ramable but still tough enough for floors or forge doors. It is also a bit more insulating than ramable so it heats up quicker. I love this stuff. Another construction technique that us blacksmiths are mostly unaware of involves the way to install blanket insulation. This method differs from just wrapping a single layer of Frax blanket inside a steel cylinder. The technique is known as the "accordion fold". The first step is to fashion "core form" for the desired i.d. of your forge design. Working with the steel cylinder in a vertical upright position the "core" is temporarily fixed in the center of the cylinder. A length of galvanized flue pipe works well for this. I use 1" thick Frax, IMHO the higher the density takes more heat and is worth the $$ difference in the long run. Now the fun begins! The frax is first cut into 5" or 6" wide strips of the required length. The strips are soaked with water, folded in half lengthwise and squashed flat between a pair of pine boards. This results in a "V" shape, like an, accordion fold. BTW this process does no harm to the Frax. Now you begin inserting these folded strips into your forge setup. Do you see where this is going guy's? You just proceed around the diameter until the cylinder is packed. NOTE* The last few strips can be a bitch to work in so I used a couple of strips of cardboard to reduce friction. As the frax dries out it expands and locks itself in place! Wait a day or so then remove the "core" Oh, applying a little vaseline to the "core" BEFORE you pack in the Frax will help with the removal. So , this is quite a bit more work BUT: No more worry about the blanket falling away from the cylinder! Also the 1" thick Frax is now, in effect 2-1/2"-3" thick! You will need to monkey around with material dimensions to end up with the desired forge i.d. Use a razor knife to cut open the burner ports. A coat of ITC-100 seals it all up. Congratulations you now have a forge lining that should be trouble free for YEARS! That's enough for now. I have some other "Kinks" stolen from the glass gang. Such as: a cheaper, as good as, alternative to ITC-100. The use of colloidal silica as a binder/stiffener for Frax. And making shaped, cast burner ports to improve burner tip life an efficiency. If any of this makes sense to you all I'll compile a list of products and sources. Works for hundreds of glass blowers and I see no reason we shouldn't borrow the ideas.
Forge Ahead! Glen G. in Pittsburgh
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Definately would like to see a list of materials and sources! Always looking for what's usefull and where to get it.
GA
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On Mon, 21 Feb 2005 10:23:25 -0800, "Greyangel"

This sounds a lot like construction of the forge ovens at tool company where I use to work but on a smaller scale, those were roughly of a quancet design ith the sidewalls/ceiling made in that manner but with blanket folds somewhere around 6 to 8 inches thick, but then the fireboxes where about 2 to 3 feet from door to back wall and about four to five feet wide with doors that would open to about a foot. They just used a bed of crushed yellow limestone for a floor. There was a good reason for the 30 foot ceiling in that department, even in the dead of a Minnesota winter with all the upper vents wide open it was rarely less than 85F in there, in summer it was hell to even walk through it, it kind of made me glad that I was a machinist at the time rather than running a drop forge.
If some one told me that the oven on the 3500 pound hammer took as much gas per day as it takes to heet my house all year it wouldn't surprise me at all, the thing sounded like standing beside a jet engine. Bear
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Hello all, Here is some source info for the stuff I have been talking about. The URL listed is a cheapest source for blanket insulation that I have seen. I have NO IDEA about the quality of their products or their service. <www.uu77.com/thermalinsulation/> .................................................................... Two sources for #200 mesh milled Zircon (Zirconium Silicate) are:
Ceramic Color & Chemical Co. Box 297 New Brighton, PA, 15066 Ph.# 724-846-4000 ................................................................
Zarcar Products 110 N. Main Florida, N.Y. 10921 Ph.# 914-651-4481
"Zarcar also supplies Colodial Silica" .......................................................
All of the information I put out for this thread came from Dudley Giberson. Dudley has been building furnaces and making glass for eons. He put all of his wisdom in a great book called "The Glass blowers Companion" It costs $35. and is obviously geared towards glass blowers BUT, there can is a LOT of crossover info here. The book is all about furnace designs and using refractory materials. It's a great book and worth the $$. Contact Dudley at:
Joppa Glassworks Inc. Box 202 Warner, NH, 03278
Dud also sells Zirc & Colodial Silica. Tell him Glen Gardner sent you.
Now get to it boy's
Glen G.
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Just to keep everyone up to date, it seems that Zarcar Products is no longer in business, at least the number above doesn't work, and I can't find any reference to them on the web. Any one know better?
Unfortunatly, Ceramic Color & Chemical Co. has a $250 min purchase. However, in 100 pound lots, the 320 mesh zircon is $1/pound. If only I needed 250 pounds...
I found some colloidal sillica, on the web, that's used for epoxy/fiberglass resin. It's a West Tech product and comes in 5oz to 8z containers. I'm fairly certain it's a dry powder. Does any one have any idea about how much liquid "binder" I can make out of one of these. (This is what I was going to get: http://www.defender.com/product.jsp?path=-1 |10918|12212|309318&id717)
I've tried emailing the tech support at West Tech to find out roughly how much I'd get out of a can, but got no response after a couple of days.
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Here's a tinyurl for the Colloidal Sillica, above: <a href="http://tinyurl.com/4paf5 ">http://tinyurl.com/4paf5 </a>.
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J.P.' I gave a bad URL for "Zircar Ceramics". I think they are still around for the colodial silica. I know the "silica" product that your found at West Tech. It's also called "micro ballons" it is used as a thickening agent. I am not 100% sure it's the same thing but it very well might be. I imagine you mix as much as a given volume of water will suspend. Check the URL below and give a holler if it works out.
Glen G
http://www.zircarceramics.com
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gang.
cast
this
If you don't mind, I'd really like to hear about the alternative to ITC-100. I just built a forge that I'm about to coat, and if there is a decent substitute, I'd love to hear about it.
Thanks for taking the time to write up what you have so far. Do you have any glass sites or lists you'd recommend?
Jeff Polaski
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Here's some archived text (not written by me):
"The active ingredient in ITC #100 is Zirconia powder, which you can find far more cheaply as #200 mesh 'flour' on the Net. I do not know what they use for a binder. However colloidal Zirconia should not need a binder. Starting with something as fine as #200 mesh, you should encounter a high percentage of colloidal particles in your mix. You can easily acquire them by water separation; stir the powder into water, and that which stays suspended after a few minutes is, by definition, colloidal."
GWE
snipped-for-privacy@rgs.uci.edu wrote:

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Grant n'all, Yeah, the glass blowers recipe uses 200 mesh Zirconia powder. The binder they use is "colloidal silica". Just mix some Zirc powder in with the silica solution to a watery consistency and brush it on whatever you want. The colloidal silica is also used on it's own as a stiffener for blanket insulation. A VERY durable coating for fiber furnaces and forges is achieved by first saturating the bare frax lining with a 50/50 mix of water and colloidal silica. Followed by a thin coat of the Zirc slurry. THEN, a 1/8" coat of Satanite (or similar) finish this off with another wash of the Zirc and you have as tough a coat as is possible. A pint jar of ITC runs about $40.00! For about $100.00 you can get a gallon of colloidal silica and several pounds of fine mesh Zirc. This will coat and maintain a lot more surface area. I will post a source list in a day or so.
Glen G.
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On Wed, 16 Feb 2005 14:30:58 -0800, Kelley Mascher

What causes this with flux ? Is it the fluorides / borates ? Does plain glass cause the same trouble ?
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Andy Dingley wrote:

I may be completely wrong here, but my impression is that flux does the same thing to the ceramics that it does to the scale on a piece of iron when you're welding. The combination of flux & scale melts at a lower temperature than either one alone, and that's cooler than welding temperature.
- ken
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