Forges 101

[Frosty]

How straight can I be with you Cam? I'm about to tell you things you probably won't like, not to be mean but to maybe stop you from making some monumental mistakes. I'll start small till I get an idea how you're going to take it.

First, you're trying to cover too much in one post, I understand ADHD but you have to realize you're just making a hash of some basic statements and thoughts by lumping a bunch together. Try to stick to one thing at a time, it'll help really it will.

I hate to tell you but like so many other folks, myself included, your forge design should be scrapped it has virtually no workable features. It could be MADE to work but it'll never overcome the bad aspects.

Another thing, I have a thing for trying to standardize the jargon as much as practical. Iforge is an international forum and the shorter the list of terms we have for any given thing the less confusing it is. You'll hear about your improper use of words and terms. Don't be surprised nor hurt, it's not meanness it's folk wanting as many people to understand as possible. 

Point in fact, Smeltery is a term from a video game and frankly meaningless in the real world.

Smelt refers to refining ore into a metal and I strongly doubt you're collecting bauxite or lesser ore and making aluminum. If not you aren't "smelting." PERIOD. 

You want to make a "Melter," a device for melting metal. It may sound minor but its a major thing if you want folks to understand what you're asking and you want to understand answers.

That's enough for now, maybe too much. I'll be happy to help you with your forge, burners, etc. but lets take them one at a time, say the forge, JUST the forge.

Okay?

Frosty The Lucky.

[Mikey98118]

The whole point of ribbon burners , is that they make a bunch of little flames that are quickly slowed down in heating equipment. Unfortunately that also means that they aren't likely to circulate properly around sharp bends. A like your choice of forge shape, but a couple of small high speed burners are what you need for it to succeed.

Also, you will want those burner positioned low and facing upward.

[CamCarpenter]

13 hours ago, Frosty said:

your forge design should be scrapped it has virtually no workable features. It could be MADE to work but it'll never overcome the bad aspects.

Hahahaha I haven't even built my forge yet, and it's already gotten me burned!

Dang, Frosty, I thought your username was because you were from Alaska, not because you were so cold! 

But seriously, I know this is my first go, and I haven't seen any other hexagonal forges so I'm not surprised it isn't going to cut it. I would like to know why, of course!

I knew I was coming in to this with very little knowledge. I have scraped it all together from around the web, not under anyone's guidance. I don't want to make monumental mistakes, and that's why I came here.

I am not deeply attached to the hexagon shape, but do you think the ribbon burner could be made to work in a forge? I've seen a few of them and I really like the concept.

And thank you, Mikey98118 for the advice how to make my hexagon forge work, but I'm not so attached to the idea that I can't change it.  I will listen to the advice here and make a more functional forge.

I am all ears.

[Frosty]

 It's good to see you're not as touchy as a lot of folk who've put so much into something.

Your plans haven't gotten you burned, not at all. You use rendering software like I use graph paper. I look at your drawings like concept drawings. I typically 86 a couple few pages of initial sketches before I start to seriously work on a drawing. It's just part of the process, I probably tossed half a dozen sketches of the form to  make the NARB. They've save you from getting burned with a dust catcher of a first forge, I have several laying around.

I get too hot too easily, always have but the TBI made it a major issue. My last name is Frost, what else am I going to have for a nick name? Not Jack, I am not the trickster, no Loki and don't respond to jack at all. There's a short story there but for another time.

A hex is a fine shape, the shape isn't the issue. Any problems are easily resolved or mitigated, they're not as significant as with a rectangular or cubic chamber. No issues. The pluses outweigh the negatives many fold. I love hexes for many reasons but another time.

It's too large, the width isn't bad but the length is really excessive. You can only work 4-6" length at a time realistically and keeping steel at forging temps without refining the grain under the hammer causes excessive grain growth which makes steel brittle. On the occasions where you want to heat long sections say large scrolls or twists a pass through lets you slide the work back and forth through the forge and heat long sections evenly. 

Just because you have fire brick doesn't mean you have to use them, save them for your melter where they're more appropriate. In your design they make the OD about 5" wider and taller than necessary and make YOU build the frame to keep it together. A 14ga. sheet steel shell is WAY stronger than necessary to support anything you'll be heating in it. 2"square is an enormous amount of work by hand but it'll fit nicely. 

2,200 Rutland has much too low a working rating to survive in a propane forge. Kastolite 30 has a maximum sustained temp rating of 3,000f and is an alumina refractory so is not only has the heat rating but the binders used for alumina refractories are much les susceptible to molten borax welding fluxes. It's also a bubble refractory containing evacuated silica spherules as part of the aggregate making it physically lighter but better for us a pretty decent insulation. 

The Iforge store sells small quantities at a reasonable price so you don't have to buy a 55lb sack. The link is at the top of every forum page. He also carries Plistex kiln wash which is HIGH alumina and fires to ceramic hardness for the last layer of armor on the flame side of the liner.

Ribbon burners are only more effective in special circumstances and not so great as a general forge burner. I have very successful ribbon burners in my forge and it's a PITA waiting for work to come to welding temp. They have their place for sure but they're not superior except in certain circumstances.

Placement of whatever burner you use is important. Aiming them straight down from the center in a hex forge is about as poor an alignment as you can get. It will cause excessive back pressure on the burner and inhibit air induction. But that's only a factor effecting NA burners and you're planning on using a gun (blown) burner so you can get away with back pressure.

And lose the brick on the floor. I know it's traditional and a number of commercial forge companies still use them but the negatives outweigh the non existent positives. If you use a modern hard refractory inner liner and kiln wash it with a high alumina product your liner will LAUGH at molten flux. The brick will slowly dissolve from flux erosion. The deep spaces between brick and the forge walls will cause bad turbulence and result in flame shadows, AKA cool areas. The brick floor will eliminate the positive flow aspects of the gentle corners of the hex shape. 

When you calculate the shell size you use the desired VOLUME for the base number. The end volume is the important number for calculating burner size and placement the outside dimensions are only important for bench or stand size and materials purchase. To get your desired interior size, say the 4.5" floor in the example I'm using remember to ADD 2x your finished liner thickness to the OD. the liner is on all sides so it increases the OD by 2x it's thickness. For two 1" layers of ceramic blanket refractory + 1/4 castable refractory hard inner liner you have to add 4 1/2" for the OD. The thickness of the kiln liner isn't significant but add 1/8" if you want to try for close specs.

I'm starting to ramble and am in danger of making it all needlessly complicated. 

Remember, it's YOUR forge build it how you wish. I'll make suggestions and hopefully prevent you from making mistakes. If you decide to go with your design as drawn I'll do my best to help you make it work. 

Frosty The Lucky.

 

[Irondragon Forge ClayWorks]

The hexagon shape is pleasing to look at, however it limits the amount of floor space you have. After all the work rests on the floor when being heated and that shape limits the space.

[CamCarpenter]

Frosty,

Thank you, I'm glad you appreciate my sense of humour, I don't want to come off as blasé, haha. I appreciate that you are taking the time to show me where I'm going wrong to get me up to speed. I can't presently afford a blacksmithing class (either the time or the money, unfortunately) so your advice and the advice of others here on the forum is as good an education as I can get right now.

I have a few questions to clarify some points of interest I had in what you wrote, I will try to be concise.

31 minutes ago, Frosty said:

There's a short story there but for another time.

I would like to hear it some time, haha, you've definitely piqued my curiosity.

32 minutes ago, Frosty said:

A hex is a fine shape, the shape isn't the issue. Any problems are easily resolved or mitigated, they're not as significant as with a rectangular or cubic chamber. No issues

Are you saying hex is better or rectangular or cubic? I'm not clear on that from this comment.

 

Re: the size, I made it that long in case I wanted to heat treat a longer blade. I didn't know that having metal at forging temps without hammering it affected it's strength! That's the kind of advice I'm grateful to get, rather than wondering why I'm breaking so many things haha I suppose I won't likely be making anything very large for the first while until I get the hang of the basics on smaller projects. I chose the width to fit my crucible, how long would you recommend the forge be? 8 - 10"? (Quote below because formatting on a phone is hard)

49 minutes ago, Frosty said:

 

 

46 minutes ago, Frosty said:

It's too large

34 minutes ago, Frosty said:

Just because you have fire brick doesn't mean you have to use them

Fair, I only use them because I have more materials than I do money right now. I don't have any 14ga steel kicking around, but I do have fire bricks, angle iron and a welder. I can make the size whatever I need by cutting the bricks, so that's why I was thinking that. Where would you suggest finding some 14 gauge steel to work with? Maybe I can get some next month

Re: the refractory cement. ok. I will look into Kast-O-Lite 30, thank youfor letting me know about the store. Is my 2200 good for anything forge related or pretty much just outdoor stoves? I don't intend to build one so I'd likely just try to sell it if I can't use it for something related to this.

38 minutes ago, Frosty said:

Ribbon burners are only more effective in special circumstances

Oh, that's not the idea I'd gotten, that makes them less appealing for sure. I had thought they were more efficient than venturi burners and used significantly less propane. It seemed a logical choice since I'm trying to reduce my overhead. If it adds time and cost, I don't want one for now. I know they're good for heat treating to avoid hot spots on the steel, and I want to leave my doors open for knife making. I'm still not sure where I'm going yet with blacksmithing but I figured might as well leave the opportunity to be a knifesmith (if that's an official term :P) do you recommend a different kind of burner?

50 minutes ago, Frosty said:

lose the brick on the floor

Done, I'd rather save the space anyways, I only added it because I thought it was wise, but I'll take seasoned advice over a Google search lol

52 minutes ago, Frosty said:

calculate the shell size

What do you mean by this? The 14Ga steel you were referencing? Like the outside shape of the forge you mean?

It didn't seem like rambling to me, it seemed like helping me redesign my forge from the ground up, which covers a lot haha

I know it's my forge, but I also know I have no experience. I don't want to waste my time making an inefficient, gas hungry forge with cold spots that will not survive two heats lol I appreciate all the guidance. I did my best with what I'd learned, but I will not say no to instruction.

21 minutes ago, Irondragon ForgeClay Works said:

The hexagon shape is pleasing to look at, however it limits the amount of floor space you have. After all the work rests on the floor when being heated and that shape limits the space.

I guess that's why I saw a few pentagon forges when I was designing mine. Less wasted room around the sides. Hexagons are pleasing to look at but if I have to pay for it with gas, then it probably won't be worth it to me haha

Thank you for explaining that.

[Frosty]

You're over using the quote function, a mod will remove them and leave a message why in their place. Some aren't effective at all, I mentioned stories for another time at least twice and the quote doesn't let me know which one. Hmmm?

Time and money are always a balancing act, if you have the time you don't have the money and if you have the money you don't have the time. Welcome to the real world, I'll bet Plato related a version of that adage.

There are alternatives for a fellow wanting to get right to heating steel but has more materials than time or money. While you're keeping your eyes open for ANY sheet steel up for grabs, alleys, roadside ditches, perhaps the rem pile at a local sheet metal fab shop, etc. AND if the brick you have has a high enough temp rating, 2,600f is generally acceptable though the rapid thermal cycling of a propane forge may degrade it rapidly. Old insulting fire brick are like that, they last 2 maybe 3 firings of the forge before they begin to crumble. Morgan Thermal Ceramics K-26 IFB (Insulating Fire Brick) has a maximum sustained temp rating or 2600f and are not silica based so survive borax based welding fluxes. They're pretty economical too if available without shipping. Check with HVAC service or supply places, if they don't carry it they're know who does.

Anyway, assuming the IFB you have now will do the job, make a brick pile forge. You literally stack IFBs on edge making a chamber the size and shape you want, leaving a place large enough to poke your burner through. Viola!

Below is a pic of a clamp together version our club made in a two day burner / forge build clinic.

It's made with 10 K-26 IFBs a few feet of angle iron and all thread, nuts, washers, etc. and is powered by one 1/2" T burner. The club bought the materials in bulk at a discount members paid materials cost + a modest profit. Everybody benefitted including the club the treasury. If your brick is suitable and you have the angle iron, forge and burner are probably $25-$40. The regulator and hose are the next big money item but not bad online.

I took this pic about 3-4 minutes after lighting this one for the first time and a member stuck a piece of steel in immediately. There are IIRC 4 professional bladesmiths in the club who built one of these on a lark and to help support the club none of them light their old forges except on special occasions. One is a locally known axe maker. The chamber is 4.5" x 4.5" x 9" and if a person needed longer slide another one close and enclose the space between with K-26 IFBs for a 20"+ long 2 burner forge. Heck make it as long as you need.

 

The basic brick pile forge isn't this fancy just lay IFBs flat for the deck, make it larger than the forge chamber and lay brick on edge to define the size and shape. Extra wide is a bit of a problem I resolve by making the sides double thick and cantilevering the roof bricks over the chamber and laying a couple heavy hard bricks on the wall ends to balance. 

IFBs are easy to cut with a saw, I use an old carpenter's saw and make burner port holes with an old dull hole saw. You can then make the burner port holes into tapered flame nozzles and improve the burner's performance with a little creative use of a hand drill,  emery cloth and tape. Wear BREATHING and EYE protection !!!

A number of members have discovered these little beasts are all they need and this clinic was IIRC in 2016.

The insides are kiln washed with Plistex and done before they were assembled. We laid a couple cases on a brown paper covered work bench and painted them all at once with a cheap broad paint brush. by time the frames started coming online the bricks were dried enough to assemble. Plistex fire cures and with as little time as we allowed the thickness we applied needs about 30 seconds of burner to dry completely and it's ready to take yellow heat and go to work. Unlike the impatient fellow and the pictured forge, he scraped some of the kiln wash off the forge floor and we gave him a little grief about it. It was a nothing to repair though, just a quick swipe with a brush and fire cured it later. EZ PZ.

I keep a case of K-26 IFBs on hand to model new forge designs before building the permanent, "improvement(?)" It also lets me set up a one shot forge for weird shaped or size projects. Say I wanted to do some repousee on a car hood. 

Oh, do NOT try to make a dual purpose furnace, make a forge OR a melter. Anything made to do multiple things does none well. If you make a brick pile forge, just rearrange them into a melter. Hmmm?

Frosty The Lucky.

P.S. which story for later did you want to hear? 

 

 

[ThomasPowers]

Have you checked with the local smiths?  One might be willing to teach you the basics for FREE.  I know that I've done that for years to pay forward all the folks who helped me get started!

BTW are your firebricks insulative or not?  I probably missed that in all the writing and a lot of folks make the mistake of using hard uninsulating firebricks in their first gas forge explaining that they need to save money and so spending 4 or 5 times as much for fuel will save over spend a few dollars for proper insulating refractory.

And some of us do do smelting making metal from ore.  I'm planning a run for this summer; saving up my forge scale and looking for other magnetite sources locally.  We do get peeved by folks wanting to melt metal using the term smelt metal. It seems to be becoming more common as it's spread on the internet.  Generally I assume that anyone who can't use the correct terminology isn't doing their basic research and so probably not going to be successful...

[NoGoodWithUsernames]

As Frosty stated, if you want to just start heating some metal without investing a lot of time and/or money, another option to look into is the JABOD (just a box of dirt) It is very inexpensive and can usually be made with stuff laying around. lump charcoal is relatively easy to obtain, I know our Walmart has even occasionally carried it. Tractor Supply and I'm sure other similar places will also carry it. 

I used a small JABOD for a while waiting to buy supplies to build the propane forge.

[Frosty]

Cam: What kind of brick do you have? I was thinking Kijiji was a brand of fire brick NOT an online marketplace. 

This is a BIGGY, it's make or break important.

Frosty The Lucky.

[Mikey98118]

Actually this forge shape has been done occasionally by guys who show us photos, and I get all excited that we're going to hear something new, but then, so far, there has been no follow through. Then I feel like the canary got away, and again, and got left with a feather

Maybe we gots to be nicer, if we're going to entice one of these guys to speak up!

[Frosty]

I don't think I drove Cam off Mike I think he's thinking and drawing ideas between work and the kids. I think we were getting along pretty well, I hope so.

I'd like to see a hex forge up and working as an active member's regular forge. I've seen them before sometimes HOT but I've never heard back. It'd be nice to know how they work as a long term tool.

I try to be nice but I can get carried away or rubbed the wrong way too easily. I delete and edit my replies  before posting as a matter of course. 

People who come here for help and answers don't deserve to have nicey nicey smoke blown up their 3rd points of contact. No honest question or mistakes deserves a mean reply derision, etc. and sometimes I use examples that can be taken as sarcasm rather than an exaggeration to make the point. 

I try though.

Frosty The Lucky.

[Mikey98118]

Frosty, I wasn't making a dig. Kathy thinks I'm about as subtle as a club, so I don't play with that toy

No, I'm just noticing something missing that needs seeing to; fishing, fishing. Maybe some of those others will get back to us. Information is always nice. Especially information about innovative brick forges.  We both know that brick can be childishly simple to build forges with. And brick is a very likely source for innovative refractories. I don't like to see anything good being overlooked.

A couple of years back, some guy showed us photos of his tiny brick forge, heated by a propane torch. Now, somebody is making quite a good thing out building one commercially. I think there is going to be a lot more small brick forges sold that way, which is good. But I don't want us falling behind the class curve.

[Frosty]

 I didn't think it was a dig Mike. I've been trying to ease off being curmudgeonly, I can be too hard on new guys. I took it more as a heads up from a friend. 

I'd like to see more new shapes and types of forge construction too. Lots of new shapes and types! 

As much as I love the hex I can't think of a way to do it well without too darned much work involved. It's not so much difficult in principle, it's just too darned finicky to get to come out well. 

If we wanted we could just order K-26, hex forge bodies from Morgan Ceramics and mount burners. But what fun would that be?

Frosty The Lucky.

[Mikey98118]

Actually, I would rather other guys invent the great new forges; the more the merrier. My tired old hands are full just trying to finish my finale burner book. If that gets done no one will be more surprised than I. It is still great fun when one of them comes up with a slick new forge design, though

1 hour ago, Frosty said:

It's not so much difficult in principle, it's just too darned finicky to get to come out well. 

What about the hex walls held together with refractory cement, as one part, which is trapped between two flat sides, which are held in place with angle iron and all-thread?

[Frosty]

I think about forge designs but never seem to remember when I'm in the shop and do the prep work. I'm feeling like I've built enough, the next one won't happen until I need one. My too large shop forge is still going strong so. . . 

That might work, IFB or kiln shelf?

Another thought was to carve a styrofoam hex, cover it with linoleum roll kastolite to 1/2" thick and wrap the form and drill the burner port(s). When it's dry wrap it with rigiized kaowool and make it a skin. 

I built my first successful propane forge from the inside out. 

Frosty The Lucky.

 

[Mikey98118]

I don't think younger guys have the same ideas about what is hard or easy as we do

For most of my working life, just staggering through to the finish line, wade down with other peoples mistakes and arbitrary demands was considered an "easy" day. By the time we had accumulated any personal power, the bosses just dumped responsibility for entire steel crews made up with the average loser idiots on our hands, to keep us in line. By the time we'd learned to joggle with that load, we raised our heads up to "spit in the boss's eye," and our sight was growing dim with age.For some strange reason, the following generations decided not to by in to our 'good ' deal. Nope, we ain't getting them to jump into the People's Pool.

MorganK26 bricks and Plistex on their inner faces. I only ever cared for high alumina kiln shelves as slide out coverings for forge floors and for door baffles; they are just too expensive for any other use.

[Frosty]

Did you when you were young? I sure didn't. I knew what a hard day's work was but not how to evaluate project's for minimal hassle. I grew up in Dad's shop and got lectured about minimizing steps and labor and maintaining quality. Owning your own business is a business of fractions from the redline.

I was still in my late 20s before I started planning for ROE. The most bang for your buck is where the T burner came from. I had parameters a goal and examples to copy. Ron and I didn't know each other when we started but it wasn't long after Theforge.list came to my attention. My goals was an effective propane burner that required minimal skill and equipment to make.

I took commercial ejectors apart on "paper" till I had something to experiment on, bought some plumbing and made the mark 1. When I ditched the old lamp rod mark 1 for the brass fitting jet mount it was nothing but fine tuning construction methods from then till now. 

NARB came about for the same reason. The long established gun version was just crazy inefficient, no gas forge that has several FEET of dragon's breath is right. Sure they get steel HOT but look at all that propane burning OUTSIDE the forge! I have to pay for propane I want every joule I can get from it. It's that old ROE again.

Frosty The Lucky.

[CamCarpenter]

Firstly, I just want to apologize for my absence! I intend to post once a day (as long as there is something to say, anyway!) but I was down with the flu. My wife and I were both just helping each other limp through the last few days between the kids and each other haha. Not a lot of time to sit and think about the forge.

I had a chance to read your reply before I left, Frosty, and I've been thinking a lot about it. There's a part of me (the young "I know what I know because I read it!") that wants to stick with the hex forge, but I've learned through carpentry, generally experience is a greater guide than academic knowledge. It hurts to acknowledge the best place for me to start might be the basics, but I hear the advice and I am encouraged that you're taking me seriously. None of you want me to give this up and you only met me a few days ago. I am grateful for the best-practice advice. Now, I don't mean to get too sentimental, so I'll get back to the forge.

I cannot be sure about the bricks, I just bought them off an online marketplace and they were listed as firebricks. I have attached a picture, in case there's anything you can determine from that. They're ~9" x ~4" x ~2" and they don't look like standard masonry to my untrained eye. Hopefully I didn't get ripped off, cause I paid $2 CAD a brick haha.

I had thought making a multipurpose tool would be a better use of materials, but I see you suggest that I choose forge or "melter" (I will be careful to use that word from now on, I promise ) and honestly melting is only a half-interest to me, so I'm going to focus on the forge part of things.

I'll use the bricks I have for now, unless one of you changes my mind, if they break down rapidly, oh well, I have 50 of them. If the forge is small enough (and that model you showed me looks like it only uses a half-dozen bricks or so) I can make the forge a few times if it breaks. If it keeps breaking, I'll keep in mind those Morgan Thermal Ceramics K-26 IFBs you mentioned.

Acknowledged on the breathing and eye protection, haha I've seen masonry cut and know it can be quite dusty. Wikipedia says emery cloth is like an adhesive backed sandpaper, is that right? You mean for shaping the openings and whatnot in the brick?

I am interested in your suggestions, Frosty, (and other guys, too, but Frosty has been most direct haha) do you suggest I start with this forge as pictured below?

On 5/20/2022 at 12:37 PM, Frosty said:

 

I'm sorry, I'm asking so many questions, I almost feel like I should number them, but then it just feels condescending, like I'm giving you homework lol

I have 48 firebrick, about 6sqft of 1" kaowool, 20lbs 2200° refractory, (still don't know if that's completely useless for my purposes or if there is something I can use that for?) I have access to 1 1/4" angle iron, little 120V welder, and Amazon. I was planning on seeing if my dad has some 1 1/2 or 1 3/4 piping to make my fuel/air delivery system.

My current plan (which I am slowing down to make sure that I am getting the full benefit of the advice here on IFI) is to get a 6' propane hose to attach to the barbecue tank I have, and I have seen a few designs online for how to do the propane needle inserter that I like, though they're all blower systems.

Last question for this post: Frosty, I hear you talking a lot about this T-burner (which I assume is the design pictured above) do you recommend that over a blower if I have access to electricity? I would have assumed forced air would always be better.

I'm going to wrap it up here because I feel like I've asked a million and one questions haha. I just want to make sure I'm getting all this information clearly so I can start making a forge this week, hopefully.

P.S. The story I was interested in was why you were called Frosty, you said it was a story for another time, haha, nbd

Edited May 22, 2022 by CamCarpenter
Removed question about NARB, read the "Acronyms and Abbreviations" page

[Mikey98118]

I recommend Frosty "T"  burners as the sensible choice in box forges. And of course most brick forges are box forges. Why especially sensible in box forges? Well, "T" burners have the softest flames of any really hot burner design. That allows them to do a satisfactory job with top mounted, facing down; this is the only convenient position and orientation for dong a satisfactory job of burner mounting in brick forges. It all just goes together nicely.

With Mikey burners I would recommend mounting high on one side wall and aimed at the other side wall. This gives quite satisfactory performance, but is anything but convenient to mount

[Mikey98118]

Also, Mikey burners are anything but convenient to build. I designed them for performance, not construction ease. Of course, if we're going to work that hard to build something it should last forever, so I designed them to be made from stainless steel parts. Unfortunately S.S. parts in small quantities is one of the many many things that suppliers are vastly over charging on these days... it's far from nice, currently

[CamCarpenter]

Mikey98118,

Is there anywhere I can read about the Mikey burner? I am not averse to a little setup work and do like performance, haha. I understand about suppliers overcharging for supplies, I'm a carpenter by trade and it is hard to convince anyone to build anything right now with lumber prices the way they are haha

[CamCarpenter]

I just realized I forgot to attach the photo of the brick I have. This is it half wet half dry, not sure if that helps or if there is another way to test / know if it's fire rated.

[tinkertim]

Hiya Cam,

Does it feel very light or quite heavy?

Were your cuts done with an angle grinder or a simple hand saw?

Light & hand-saw = Insulating Fire Brick (IFB).

Heavy & Angle-Grinder = Dense Fire Brick.

GOOGLE for "insulating fire brick" and look at images.

IFB's are generally off-white and porous, hard fire bricks are generally pale off-yellow and have a smooth-ish surface.

To me, that picture shows a hard fire brick.

Hope this helps,

Tink!

[CamCarpenter]

Tink,

Thank you for the quick reply, I am certain, by your description, that this is not a light fire brick. It is a pale off-yellow colour (maybe with some red?) and it's heavy. I've had to grind a few down (those cuts were already there when I bought them) and they are quite hard to shape.

I was just hoping it wasn't some off-type standard brick, because I doubt that would be very good for a forge, haha.

Cam