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I Forge Iron

Observations of building my first forge and putting it out there for criticism.


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I've been reading and attempting to internalize everything here and elsewhere while working to build out my first forge attempt.  I think overall it went pretty well and I believe I did most of it correctly (feel free to correct me on that) but there are a few things I definitely could have done better.

My own observations are around size, I think I made it almost twice as long as it really needed to be and I notice it struggles with even heating.

Secondly, I think I've left the inside to large and I lose an enormous amount of heat out the ends.

Lastly, I am not entirely certain I have a good coating of refractory in it, it definitely has no loose wool sections but it is uneven in colour so that's a bit weird to me.

It's ITC-100 because that's what the local forge and farrier supply stocks, I've noticed comments around not using it but needs must. 

It does heat up well but takes some time and I'm not entirely sure if I am not pushing it hard enough or if I am being unrealistic but the metal I heat in it (Some 1/4" flat stock I found in a metal recycling bin) loses it's orange colour in under 30 seconds while I'm pounding on it.  I don't expect to make anything yet as I'm just pounding on metal and testing the forge but it seems that I may not be getting enough heat.

I don't really have a good side picture of how it's built so just ignore the brewing equipment in the background, it's not relevant until after I turn the propane off for the day. ;)

Appreciate any feedback on it.  I think I'm going to build another one about 1/2 to 2/3 the same of this one and keep this as a momento/future use forge.



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There's a very easy fix for some of your issues: put some doors on it! Ask at your local forge supplier for some of their cheapest firebrick. If you use these to partially block the front and back openings. Play around with how much of the opening you block until you get the level of heat and evenness you want. Eventually you'll want to add some structure to retain the firebricks and keep them from falling off. You may not get perfect evenness, but you can compensate for hotspots by moving the steel back and forth in the forge.

What kind of work are you gearing towards? That is the key factor that should determine the dimensions of your forge.

30 whole seconds?? That's plenty of time to work it on the anvil :D That's normal and has nothing to do with your forge.

The size and quantity of burners looks a little excessive. Are those 3/4" burners? Also, since the burners are mounted vertically, you're going to want to use copper tubing not synthetic, for the propane line.

What pressure of propane are you using?

Overall, that's really nice for a first forge. You should see mine :wacko:

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I've got some extra fire brick I've been using to block one end and it does help, when I have some time tomorrow I'll try and get some video of it in operation.  I've got some ceramic block I need to cut to shape as well, I was trying to make sure i didn't have anything done objectively wrong before I put more resources into it.  

Ok 30 seconds is normal? Good, I'm still mucking about and when you watch videos they tend to be a little fuzzy on exactly how long you can work the material before it cools. 

It is 3/4" pipe into the tank if that's what you mean. It's what I was able to easily get my hands on, they might be overkill but when you don't really have a baseline to compare against (The local blacksmithing groups are all shut down cause of Covid) it's hard to spec things completely accurately.  The tubing is absolutely correct, I have been keeping an eye on the lines and they haven't gotten hot but it's definitely high on my priorities to swap it out.  

I was looking at capping one of the 2 burners for precisely the overkill reason, just have to get to the hardware store and get a pipe cap for it. 

My propane regulator doesn't have a gauge on it but it's 0-20 psi and I would guestimate I have it running around 5-8 psi most of the time so far, turning it up any higher and I end up with a big flame coming out the end and some coming up through the burner tubes.  

As for what I am going to do with it, not entirely sure yet. I played around a bit with farrier work in my early 20s around 2001 but went into IT instead and with the lockdown here in Canada I needed a hobby that didn't make me as fat as brewing does. I'll probably end up messing around with knives at some point cause that seems to be what everyone does but for now I am still looking around for good beginner projects too.  


Edit: I've also been working off a couple stools with fire brick to protect them while I figure out where to put it in my garage so I don't burn the whole place down. The picture in it doesn't have the fire brick yet cause I was monitoring how much heat went down first.

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Glad you're planning on ditching the tubing. If you're not familiar, look up "chimney effect" on this forum.

It looks like one of your burners has a shut off valve. I'd use that instead of a cap.

I've never used one of these T-burners before and I'm not an expert (Mikey and/or Frosty will probably visit this thread sooner or later), but from what you're describing (flames coming up the tubes at higher pressures), I think you've got an overpressure problem. Too much pressure in the forge from too many / too big burners creates a back pressure that chokes up the flow of fuel/air mix.

The other thing I'm seeing is the way the flame is pressed up against the floor. I had this behavior on my flat forge when I tried using a 3/4" burner. I think the issue is that your burners are too close to the floor and the flame path is interrupted. Try backing the burners out a bit.

Alternatively, both issues could be addressed by making two 1/2" t burners. Check out the pinned threads on this subforum. It's very do-able.

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Yeah that sounds like a completely valid idea building smaller burners, I did actually try turning the 1 burner off and it melted the tubing. I will look into it but I think I can imagine the chimney effect.  


I like how the T-burner as you called it works but since I'm still learning, and honestly building the stuff is as much fun to me as using it I will have to poke around for different designs and buy materials to do a few different styles to see which works best.  

Part of why I'm considering building another smaller one is cause I like building stuff and I feel like I learned from this one, but yeah modifying this one also works as a learning opportunity.

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In my opinion, that's the right reason to start a new forge. I'm building my fourth forge for similar reasons.

Interesting that the tubing started to melt when you turned off one burner. I think that means that the burner that stayed on starting performing much better, either because of a lack of over-pressure or because the volumetric flow of propane increased (at a lower pressure).

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The flame started coming up the tube with the burner I turned off, it took a while to melt but it did.  I tried removing the burner entirely to see what happened, I ended up with a flame about 6" long coming out of the tube when I removed the burner.

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You might also have issues with the air intakes on your two burners being in-line with each other, so that they may fight for the same air in between them and not give an even burn.

Try rotating both your burners 90-degrees along their long axis, so the air intakes are more vertical than horizontal.  They shouldn't then risk interacting with each other.

Just a thought.


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Welcome aboard Hawkbox, glad to have you.

I really hate to discourage folk from helping others but all too often they don't know much more than you do. How much burner you need in a forge depends on the volume, shape and insulation value of the forge liner. So yes your forge is way larger than practical. Everybody does that, folk who've been at this a while have a few too large forges collecting dust in out of the way spots in their shops. I still make them too large and I've been doing this for probably 35 years or so.

ITC-100 is NOT a refractory liner. It is what's known as a "kiln wash" and rather poor for a forge. Kiln washes are the LAST thing that goes on a forge liner and lives in direct flame contact. Plistex is a far superior kiln wash for a propane forge.

Your ceramic blanket refractory looks good but it needs a couple treatments to make it safe and durable. Rigidizing with colloidal (fumed) silica mixed with water and spritzed on encapsulates the refractory fibers making them more structurally sound (stiff). The encapsulation helps prevent fibers breaking loose and drifting in your breathing air where it can cause permanent lung damage, think: silicosis, mesotheleoma and similar. 

The next is a hard refractory flame face layer. The current consensus preferred refractory is Kastolite-30-li. it is a water setting, high alumina, bubble refractory. Water setting means you mix it like concrete and it sets and cures in such a similar way you can follow the same time schedule for setting and curing as concrete. Do NOT use portland cement concrete! it is literally dangerous in a forge liner! Kastolite just mixes, sets and cures in nearly exactly the same way but it's an entirely different material. 

The hard inner liner (flame face) only needs to be 1/2" thick on the forge floor, the walls and roof work just fine 3/8" or thinner. 

Once set and cured it's time to apply a kiln wash IF you wish to. Kastolite can operate as a stand alone flame face though a good kiln wash provides another layer of chemical armor and provides a IR re-radiating surface making the effective temperature in the forge higher.

There are details for building forges in the "Forges 101" section of Iforge. Kiln washes are discussed in detail in Forges 101 as well.

The way you have your burners mounted and aligned looks good. I can't see how deeply you have them inserted, they should be just barely in the refractory liner. The burner ports through the liner material needs to be rigidized and coated with hard refractory because they WILL get HOT. The burner ports is the perfect place to form burner flares. 

Tinker's suggestion is sound, burners, especially T burners can starve each other of intake air so rotating them so the intake ports are facing away from each other is a good idea. I do it even when they're well away from each other it's a, "can't hurt, might help" good habit. 

With your burners aligned as they are the rubber supply hoses should be safe enough from dragon's breath though using copper tubing makes heat a non issue. Another, "can't hurt might help," but don't sweat it until you get the forge performing.

If you're having performance issues with your burners we can help you trouble shoot them. The guy who developed them CAN be talked into giving you a hand. 

If the floor in your forge are fire brick, loose them they are a heat sink absorbing energy from the burners to little use. 1/2" of hard refractory over 2" of blanket serves much better.

So, in short, build a smaller forge. A 300 cu/in single 3/4" burner forge is typically larger than most folks need to start learning the craft with. Don't sweat building a too large forge, everybody does, you should see my holy COW too large shop forge. 

Do some reading in the Iforge, "Forges 101" section. I hope you're good at skimming, or you'll need too devote considerable time to reading if you try to read it all. 

I haven't even touched on many other factors but I tend to get carried away and I've written detailed descriptions many times already, I need to give it a rest.  I'll be around though.

Frosty The Lucky.


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Just a couple of other start up suggestions: is your anvil and hammer warm to the touch when you go to forge with them?  This is the time of the year where a cold anvil sucks the heat out of your stock causing shorter working times---especially for new smiths!

Secondly VENTILATION, gas forges produce Carbon Monoxide and produce a heck of a lot more if the burners re-run the exhaust.  The tendency is to want to use the forge as a heater for your work area; but that can kill you.  Ventilate heavily and use the IR blast to heat you instead!  Get a CO meter that will work in the temps your work area gets to. We'd rather share a brew with you than make the parting toast for you!   (Been there, Done that, it aspirates strongly!)

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I've spent 2 days reading through it, dozens of pages with random smatterings of information is not an easy or straight forward read. I am aware this forum frowns on new users posting things that can be found eventually but at a certain point I just needed to ask some questions.

The reason I went with ITC-100 is that I've spent days trying to find Canadian sources of the other materials stated as preferred here without success, I understand the verboten nature of posting a link to a supplier directly but it makes it bloody hard to find anything.  My local farrier supply occasionally stocks it but has been out for months now, I have not found a single other Canadian vendor that I can buy it from.

We do not have the overwhelming amount of choice you in the US do, I've found numerous posts from Canadians previously trying to figure out ways around this and I never found one that succeeded.  I'm not trying to downplay needing this material but please keep in mind when you're new to this you don't automatically know what stores stock what materials.

I will probably end up having to order the material from the US with the exchange rate and customs or I will get ambitious in the spring and attempt to mix my own unless they get more in stock soon, which I have doubts.


To the forge itself, I used rigidizer rather liberally but realized after I finished this that I would have been smarter to spray the rigidizer on while it was flat and then fit it in to let it dry, would have been a lot more consistent and probably easier.  It would have been less stressful as I tried to get my arm down the tube while wearing an N95 and stressing out that I touched the material and I was going to kill myself with it.  

I put by far the most of what I thought was refractory (ITC-100) in the burner ports and I was wondering if there is a position on putting refractory on the burner itself. I have been adjusting the positioning to try and make it suitable, I notice though that the bell end of it gets orange itself and I can't imagine that is good for the long term health of the burner. Is that a positioning problem, normal, or me doing something wrong I haven't considered?

Can I put Kastolite assuming I can find it over the existing coating or is that basically a one and done situation that I should keep in mind for the next forge? I'm not terribly inclined to pull the wool out and potentially stir up the fibres.


They are 2600F rated fire brick in the bottom yes, I had made what appears to be a faulty assumption that you would want a hard and durable material on the bottom so you don't wreck it with the materials you're putting in.  My interpretation of what you are saying is I may be just as well off insulating the entire inside with firewool and then building up a flat platform on the bottom out of Kastolite if and when I can find it? 


Appreciate the feedback, need to definitely do some thinking on the Mk2 forge idea.


Edit: I guess it merges separate posts? This is replying to Thomas.

Thomas, you are very correct about the safety, I keep all the doors in my garage open. I grew up working on tractors in poorly ventilated shops so I have an appreciation for not choking myself out.  But I am going to go buy a CO monitor this afternoon, no point in mucking about.

The forge and hammer are indeed room temperature, which here right now in my garage is 10C.  I had briefly thought about that but hadn't really realized how much of a heat sink that would act as, I am assuming at this point since I've only been going for less than an hour at a time playing with things to try and line them up I haven't even brought the anvil anywhere near the same heat level before I call it a day and walk away to let it cool. 

I have a lot of secondary projects I still need to do, building a proper anvil stand (It's a tree stump right now that is not high enough), moving my bench grinder and drill press to where I can more easily use them, figuring out a permanent home for the forge that doesn't burn my garage down, etc...

Most of that has to wait until I put my motorbike back together though, was doing a valve adjustment on it and finally got the parts in I needed.  


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There are tricks to work in the cold---like holding the work just above the anvil and letting the hammer blow push it in contact and then raise up again so contact with the cold anvil is minimized.  Tricky; I prefer to heat the anvil, working in your garage means you could probably an old electric iron and use it to preheat your anvil.  When I was working outside in 0 to lower C I would hang old paint cans with holes punched in them on horn and heel and build kindling fires to warm up the anvil; not trying to get it near tempering temps just warm to the touch will do a lot!

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1 hour ago, Frosty said:

it is a water setting, high alumina, bubble refractory.

Alright Frosty, what is "bubble refractory"?

Hawkbox, Have you tried a place that makes ceramics or pottery? Or a local college or even a high school that offers pottery classes? They also deal with high heats in their kilns so they may know where to obtain the materials you need. Maybe even a large scale glass producer. I know some people who blow glass but on a small scale they use an oxy-propane torch, not sure what they would use on a large scale.


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11 hours ago, BillyBones said:

 Have you tried a place that makes ceramics or pottery? Or a local college or even a high school that offers pottery classes?

I have unfortunately, the ones local to me did not stock most of what is discussed here and the ones online are very vague as to what is actually in the material they're selling. I want to post a link for an example but I will probably get in trouble, let me see if I can take a screen shot.  It's surprisingly hard to find these materials in Canada, which is really odd to me as when I am brewing I can get the materials, they just cost more.  With this stuff it doesn't seem to even truly exist.  I'm sure there is some place I've missed, but I've literally ran out of ideas.    Advertising link removed

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Bubble refractories contain evacuated silica spheres as part of the aggregate. The "bubbles" are commonly used in concrete products to reduce weight, "light concrete." For example floors in sky scrapers that don't weigh as much without sacrificing structural integrity. You can buy the spherules at most concrete suppliers.

In a hard refractory they not only lighten it they increase it's insulating value making your forge ore efficient.

Good timing Hawk, you posted just before I hit submit!

None of the products you show are suitable for a gas forge. The ITC-100 is WAY too expensive and was formulated to act as a release agent in ceramics kilns so glazes wouldn't fire pottery to kiln furniture. Using it in propane forges is a legacy opinion, at one time it was the best that was known. It has been far surpassed in recent years. 

Plistex or Matrikote are far superior to ITC products and cost maybe 25% as much.

NO mortar, cement, putty, . . .Heck ANYTHING in that PSH ad are worth crap as forge liners. Not one will survive in a propane forge environment. The rigidizer they list works fie but is oh my god too expensive! You can buy fumed silica at a plastics or fiberglass supply, it's commonly used to thicken resin. Get the hydro-PHILIC silica or it's hard to mix with water.

Get the thought that a mortar, cement, whatever is suitable out of your head. No matter who say's otherwise. If one argues, tell them Frosty The Lucky says so and feel free to refer them to me here. 

There are a few specific products I can recommend because I have first hand experience with them. Unfortunately they sell by other names, especially in different countries.

Kastolite 30 li is a 3,000f castable refractory that is currently the best available I know of. It will stand up to forge welding fluxes pretty well.

Plistex is as far as I know the most suitable kiln wash available. Mix it with water to the consistency of thick latex paint and apply it in thin coats. Allow it to dry thoroughly between coats. If you apply a thick coat it will shrink check like a mud puddle when it dries and is much more prone to flaking during the rapid thermal cycling propane forges are famous for.

You might have to do some serious internet searching, most ceramic supplies do NOT play with the kind of fire we do so they can't be as helpful as we'd like. It's not their fault, forges are just not in their wheelhouse. Right? 

If you look at the top of the page you'll notice a button saying "refractories, T shirts, etc." This is the Iforge store and Glenn sells and ships modest amounts of all the supplies necessary to build a high performance gas forge. There are plans as well. 

Frosty The Lucky.

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OK so I may have just been blind, they have something called Kast-o-lite 30 LI G and Kast-o-lite 30 LI Plus, they have the G but not the plus.  This is the description they give, is there any major concern with one vs the other? The site is called Canadian Forge and Farrier if someone wants to google.


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Little tip about site edict. You can quote just the pertinent part of a post by placing the cursor on the first word, left click and drag (i am sure you now how to copy and paste right?) but a little box will show up that says "quote selection" click on the box and it will automatically place the quoted part in the reply box. The mods do not like entire posts quoted, especially the long ones. It takes up band width and there are people from all over the world using this site and some are on dial up. Slows everything down. 

Anyway, i will be the first to admit you are asking the wrong person here. I quit using propane a couple years ago, like i said in another post my propane forge and burner are a home for spiders now. 

I also may have been a little vague, i did not mean buy the supplies from the local potter but ask where he gets his supplies from then contact the supplier to see if they carry what you need. 

Thanks Frosty, was not sure what you meant. My grandad used to make concrete castings and would add perlite to the mix to lighten it up. 

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OH, hold out for the PLUS! A 5 minute set time is what you want for gunniting commercial furnaces, NOT lining your home build forge!

Tell the company the G isn't suitable for your purposes, if they don't carry it ask if they'll refer you to someone who does. 

Make your own rigidizer! Commercial products are really expensive and have limited shelf lives and who knows how long that can has been sitting in a warehouse or store shelf? I bought a pint can at the local plastics supply for $8.USD and used about 3tbsp to rigidize my last forge in typical overkill mode. You need two spritzer bottles, one of plain fresh water to butter the Kaowool and one to mix your fumed silica. A couple few tblsp and a few drops of food coloring in the spritzer bottle and shake it regularly as you spritz the blanket. The food coloring is to let you see how evenly you're applying it. Mostly so you don't miss spots.

Frosty The Lucky.

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I was about to ask how much silica was needed, a plastics shop near my house has something called Cabosil HDK® N20 that is fumed silica, I'm in the process of finding out if it's hydrophilic or not right now.  Naturally they want $35 for 500g of it which is much more than what you're paying so I'll keep looking but I'm not expecting much, we get hosed on pricing up here.

I'll reach out to the shop about the Plus and when they might get more or where I could get some, since they clearly have a supplier somewhere.


Billy I noticed I could select subsets about 5 minutes ago, this is the only forum I have any involvement in that has an issue with quoting entire posts so I will endeavour to keep it in mind.


Edit: Ok so that silica while overpriced will at least work from what I can gather. HDK® N20. HYDROPHILIC PYROGENIC SILICA

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I found a place in Ontario that will ship me a gallon of it for $20 which is a better deal, though if this stuff only has a 2 year shelf like as the MSDS seems to say I don't seem me using anywhere near that much.   Feels wasteful.

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4 hours ago, Hawkbox said:

I put by far the most of what I thought was refractory (ITC-100) in the burner ports and I was wondering if there is a position on putting refractory on the burner itself. I have been adjusting the positioning to try and make it suitable, I notice though that the bell end of it gets orange itself and I can't imagine that is good for the long term health of the burner. Is that a positioning problem, normal, or me doing something wrong I haven't considered?

Supposing that by "bell" you are referring to a reducer fitting being used as a flame retention nozzle, it should be getting hot; yellow hot in fact.

As to ITC 100; no, do not try using it on metal parts, which it is not designed for, and which it will not improve. Do put some of it in a water glass, or other container that you can see through, and add water a little at a time until you see the cruder particles fall out of solution. Paint what is left in solution right over the coating you have already spread on the forge walls, and watch how much hotter your forge gets afterward. There is no nasty import tax on knowledge--yet.

Your forge build is basically sound; it mostly needs some tweaking. Just make improvements, one step at a time, and all will be well.

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