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I Forge Iron

Hard Fire Brick Forges


GrumpyBiker

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I've not been on here but for a minute yet I already know (have read) that Frosty has an opinion on these type of forges.

I know they're not considered efficient as they're often referred to as Heat Sinks and no professional would choose that route.

But for the weekend warrior, for the once or twice a month hobbyists, why not ?

 

And to that end is there a way to get the most from that set up?

 

**** Obviously I'm asking as I'm building a small one to tide me over till I replace my shops air compressor which I'm planning to use for a double burner set up.

So for the gurus on here, if you were restricted to using a propane fired brick forge how would you go about maxing out the potential of it?

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Grumpy, You have pretty well stated all the whys and why nots.  It will get you started and that is good.  Even if you only use a forge once a month you will want to move on to a better forge soon.  You could paint the interior of the bricks (the side that forms the heating chamber) with either Plistix or Metrikote to improve the efficiency.

Check out the Build a Gas Forge attachment at the Forge Supplies page at www.WayneCoeArtistBlacksmith for instructions how I like to build an efficient, long lasting forge.  By your comment about replacing the air compressor you have not told what size tank you have.  I feel that a Freon tank or a 20# Propane bottle will build a plenty large forge and over that is mostly wasted.

Let me know if I can help you.  Check my profile for my e-mail address and phone #

Wayne

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One of my compressors that's on its last leg is the smallest portable one I use for driving finish & brad nails.

Its a 6 gallon tank.

Should be about right for my needs.

Once it's build & running my plan is to give the brick forge to a friend who's interested in getting into the hobby but has a couple kids that tend to command a lot of his spare cash.

figure it's always nice to "pay it forward" when you can.

 

 

Heres what I'm looking at doing temporarily. I've begun cutting the metal to frame it. It's around 268 cubic inches & with that little mini mongo burner I figured it should get me by & show me what I want & don't want in my final set up.

 

 

 

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And the obligatory YouTube video of it.....

 

 

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A lot of people like ITC-100 it's become sort of a traditional kiln wash. However if you read ITC's write ups you'll discover it's not really intended for what we use it. It's primarily a high temp release agent to prevent molten stuff from sticking to the furnace walls. Our resident glass blower and ceramics guys use a number products to prevent stuff sticking where you don't want it.

My experience is ITC-100 won't fire to the liner so it rubs off eventually. Otherwise it seems to improve thermal efficiency and resists flux. There are products with equal IR "reflectivity" that bond to and fire a hard durable flame face in a propane forge. Metricote and Plistex being the ones Wayne Coe carries. These two products are more appropriate for gas forge use and much less expensive.

Kiln washing a brick pile forge is a good idea, fire brick, hard or soft is susceptible to flux erosion. Soft fire brick tends to be dissolved by molten flux like a sugar cube in warm water.

Frosty The Lucky.

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Actually , grumpy a professional might very well get along well with your set up as he can fire it up when he walks in the door in the morning, do paperwork and other non hot work wile it heats up, forging for 5-6 hours then shutting down or turning it over to the second shift. The problem for a hobiests is the mass, an old Adobe home takes 1/2 a day to heat up or cool down wile a stick built house heats up or cools down rather quickly. Same with are brick vs soft brick hard brick heats up real slow but holds a lot of heat, wile soft brick heats up fast and holds little heat. 

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Yikes! I replied but hadn't read the whole thread, that'll teach me. Brick pile forges have their place but rarely as a daily user unless you're a commercial operation. As Charles says hard brick is a tremendous heat sink that takes a lot of fuel and time to bring to temperature while having the insulating properties slightly better than an equal thickness of limestone. To give you a handle on that, the insulation rating R1 passes the same amount of heat as 1 foot of limestone. R=rock in the nomenclature.

The thermal mass has it's uses as it prevents the furnace temperature from dropping as far with the addition of new steel. The only real advantage to high mass is if you have a high rate of turnover, lots in and lots out. Most commercial furnaces will have a backer liner of light fire brick or refractory blanket. Without it the outside of the furnace gets REALLY HOT.

Soft insulating fire brick is a much better insulator, has lower thermal mass but is more fragile. It will come to temperature in maybe 10-15 minutes, depending on the burner volume ratio of course. It requires much less fuel to warm up and maintain temperature, MUCH less. It doesn't have the temperature recovery time though, being less a heat sink heat is drawn down to a greater degree but the fire brings it up faster so . . . It's not till you're moving a lot of material through it quickly, say you were forging a bunch of pry bars from 1" stock, every time you put a cold one in it will absorb IR at a high rate till temperatures equalize. 

But as a hobbyist I rarely rotate more than 2 occasionally 3 pieces of 1/2" sq. through the forge at one time so minimal thermal mass isn't a factor time wise. The fuel savings on the other hand is significant. I may spend less time forging now than it can take a hard brick forge to get to working temperature. I started taking a brick pile forge to Demos so the audience could see how little special you need to give the craft a try. When I took my shop forge folk got the impression you need something made by a professional fabricator so they'd hang a couple minutes then move on. With a brick pile and a couple home made plumbing parts burners, yeah the Ts, powering it folk are a LOT more encouraged to give it a try. A couple hundred dollars isn't unreasonable for a forge while a custom fabricated 4 burner forge or even a Whisper Moma is obviously more than most folk want to invest of giving something a try.

Anyway, I stick two 3/4" T burners in the hard brick pile forge to warm it up, then run it on one burner for the demo. It stil takes a god 20+ minutes to hit high orange. 

One serious down side to soft fire brick is it's fragile, unless you buy the expensive high temp bricks thermal cycling heating up and cooling down tends to cause them to crumble pretty soon. They're susceptible to being gouged and poked by the work, especially if somebody using it is ham handed. Lastly, hot welding flux dissolves soft fire brick like a sugar cube in hot water, you can literally watch it liquefy as it dissolves.

Soft fire brick NEEDS a good kiln wash to save it from flux. It will slow how thermal cycling as well making brick last longer. Not very long but longer. 

If you were to plaster a soft fire brick forge with say 1/2" of Kast-o-lite 30 and kiln wash that with Plistex or Metricote the liner might hold up pretty well. Unfortunately, 2" of 8lb. ceramic blanket plastered and washed is significantly more efficient and I KNOW will last a long time. Soft brick might last but I've never tried it so I'd be guessing.

have I stirred the mud puddle enough yet?  :)

Frosty The Lucky.

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Quote

 Frosty: With a brick pile and a couple home made plumbing parts burners, yeah the Ts, powering it folk are a LOT more encouraged to give it a try. A couple hundred dollars isn't unreasonable for a forge while a custom fabricated 4 burner forge or even a Whisper Moma is obviously more than most folk want to invest of giving something a try.

That's where I am with this whole thing.

Not just starting but crawling into this hobby.

Wanting to add some custom forged accent pieces to the furniture I make.

I have no desire or ambition to become a full time / full fledged blacksmith.

I'll be happy being a tinkerer , if it progresses further well, that won't hurt my feelings.

Plus I love to learn new things.

Not just the How To's but the Why's !

 

Thank you for replying. All knowledge is appreciated!

 

 

FYI- here's my Heat Sink so far.

I'll put it into its own post.

 

 

 

 

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On 8/18/2017 at 4:35 AM, GrumpyBiker said:

And to that end is there a way to get the most from that set up?

Morgan brand 2600 reasonably tough and highly insulating firebricks can be coated with zirconium silicate and 5% bentonite clay; this completely changes everything. Morgan 2600 bricks are avalable on eBay, in a variety of thicknesses, down to 1/2"; so it's not too late to keep you 2300 bricks from being ruined. With a little added work you can have your cake, and eat it too.

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@GrumpyBiker I entered the gas forge world the same way. I didnt want to spend big bucks until I knew it was something I wanted to continue with. So I made a brick pile forge using hard brick (what I coulD find locally) and a Frosty T burner. 

It did take a bit to get up to temperature. But it let me make an informed decision about whether I wanted to spend the money to make a more permanent forge. 

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Hmmmm. I either missed or skipped over past references to insulating fire brick with that high a rating. Thanks Mike, that makes a brick pile a lot more attractive. I'll have to check them out, so far my home made baffles stink.

Frosty The Lucky.

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Mike is talking about mixing your own kiln wash. Zirconium silicate flour is reasonably available through ceramics suppliers. I'm not sure where to locate bentonite clay powdered but it's used in ceramics so they may carry it too. Veegum is another additive that may have big goodness but Mike is still looking into it. I haven't gotten to experimentation yet, I'm still playing with my just about finished 2" x 72" belt grinder build. Check with the pottery supply.

Seattle Pottery Supply in Seattle Washington shipped zirconium silicate floour "Zircopax" by name to Alaska flat rate darned reasonably. 

Frosty The Lucky.

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Frosty,

You didn't overlook these bricks. Morgan has just recently come up with a completely unique 2600  insulating brick, that is only 40 pounds per cubic foot; it is at least as insulating as the 2300 insulating foam clay bricks, but is tough enough to withstand thermal cycling. Next week I will be using the zirconium silicate and a 5% binder coating on the brick, using both Veegum & and bentonite, to see how well it works as a flame coating. I expect that placing directly on one side of the brick; both materials should be synergistic in increasing thermal and mechanical strength. Yes, I've already bought the brick; it's good stuff :)

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3 hours ago, Reeltree said:

" I'm not sure where to locate bentonite clay powdered ",, I use to get it from local well drilling supply to grout wells ,, it is also used in layering dam walls in ponds

That's where I used to get it when I was drilling, I'll have to call around and see what's available locally. I can't imagine needing much more than a few cups to wash a pretty good sized forge but I'm sure MIke will have the straight poop for us soon.

Thanks Mike I was wondering how I'd missed high temp insulating bricks. I'll check Morgan out.

Frosty The Lucky.

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I'll give the feed store a call, "Brown oil tool" where we used to get it only carried 100lb. bags and I figure 10lbs. will last me a long LONG time. I suppose I could borrow my rock tumbler back and mill kitty litter with ball bearings. I'd rather just buy a reasonable amount though.

Frosty The Lucky.

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Which bricks have you got, Mikey?

Closest to the rating and density that I can find find specs for online are the K26, which I thought had been around a good while (since 2001-ish?). They look good for insulation value, but I've not seen anything on their tolerance of temperature cycling and they are a little pricy over here to just pick up a few to play with. 

I gather there's also a new JM23-400 ultra-lightweight IFB from Morgan that was announced in 2015, but I'm struggling to find any specs on it, so it may be that I've just not found the specs on the newer stuff.

 

A possible source of powdered Bentonite clay in the small amounts needed to mix at 5% with a few pounds of Zirconium Silicate might be a home brewing supplier: Bentonite is often used as finings to clear wine.

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Bentone is a refined bentonite (lower iron content for example) and indeed a lot more expensive than raw bentonite. It only takes 3 to 5 % bentone to plasticise the zirconium silicate. I have not yet used raw bentonite. Veegum is a brand name and its formula proprietary. 

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Bentonite is a clay group and refined to the degree needed for the use as a ceramic additive it's more refined than drilling mud. Veegum is in a different but similar clay group. Bentone is in the bentonite clay group and more highly refined than say drill mud, kitty litter or animal feed additive. I imagine the more refined the more it costs.

Frosty The Lucky.

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