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10¢ forge, made of Ytong


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I was carrying some repairs in my kitchen and I used the messy situation to build a forge.

A one-brick Ytong forge.


I am making this pictorial to share it with you guys and at the same time it will act as an insuarance against my laziness. If I share it with the public, I will not be allowed to stop building the forge and posting photos until it's finished. I am trying to cheat myself into finishing it. ;)



Advantages of building an Ytong forge:


1. Ytong is cheap - a huge brick like the one I am using costs about 10¢

2. Ytong is extremely easy to work with - you can make holes or fullers in it using a spoon. It is as soft as cheese.

3. You don't need to pay for or deal with Kaowool or other kinds of insulations - Ytong is an insulation itself, it's foamy and filled with air bubbles.

4. You don't need a metal container (like a containing tube, tin box, a frame, etc...) for holding the forge in place - it is self-holding because Ytong is a building material after all :)

5. Ytong is easy to obtain - everybody are using it for their interior walls, you can simply go to a building ground and ask for a brick - they will give you one and then your forge will cost you absolutely nothing



1. Ytong can be dusty when you start digging holes in it

2. Other eventual disatvantages are about to be discussed when I finish the forge and test it



So, the Ytong forge building begins.

I had only one Ytong brick left from the repairs in my home.

It measueres:

Length 60cm

Width 25cm

Height 15 cm




I had two choices: drill a tunnel in throught the brick's core or split the brick in two and carve two symmetrical fullers and then put them together to form a tunnel.

I chose the second option since I had no a tool for drilling such a long tunnel in the 60cm long brick.


So I had to split the brick in two halves.

I decided to use a power jigsaw for the job.

The jigsaw's cutting blade turned out to be too short to saw through the whole brick. I had to saw twice and meet the two cuts exactly in the middle of the brick.

The first cut:




And the second:




Ooops, the two saws do not meet in the middle. The jigsaw's blade was way too short for the job.

I just took the hand saw and sawed throught the small portion left in the middle:



We have two Ytong pieces now:



And then we started carving the fullers in the two pieces. Using this tool (sorry, I don't know it's name in English, would be glad to learn it):



Here is the first fuller:



Then we carved the same into the other Ytong piece and put the two pieces together:



We have a tunnel B)



Not too round or symmetrical, but still OK. I will refine it next time I deal with the forge.


In the next chapter I will use some refractory clay to put the pieces together and to smooth out the fullers.



To be continued...


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Now I know what you were talking about. I have never seen these Ytong bricks in the USA, but we probably have them somewhere. :rolleyes: They look like what we call "soft firebrick," but MUCH larger!


That tool you carved the fullers with is called an "adze" in English. They come with flat or curved blades. Those with curved blades are called a "gutter adze"

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Thanks, Alan.

I guess "Ytong" is a brand name. It is quite popular in Europe.

Officially, it is not qualified as a "refractory" material, i.e. it is not meant to withstand high temperatures but I've seen people using it for making ovens for heat-treating, so it must work as a forge building material too.

I believe that it is what most people call "gas concrete".


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I used refractory clay (or cement?) to plaster up the inner walls of the chamber and to stick the two Ytong parts together.

I believe that the thing is similar to the American Satanite refractory cement.


Additional Ytong pieces were glued on the seam to support the construction and to insulate the thinner walls at the seam.







It IS ugly, I know. B)


I will have to drill the holes for the two burners and test the thing.



To be continued...


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I want to drill the holes for the burners but I don't know what their correct positioning would be.

I am thinking of doing this:



Is this the best positioning, guys? What other and better alternatives do I have?

I need to know this before I drill the wholes for the two burners.

Or should I use only one burner?



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hmm... i think i'd put the burners abit closer together..... seems to me that i did the same once before.... and ended up with a cold spot between the two burners......


- but i was using just a rammable forge... and that wasn't good at all for insulation...


- yours will be much better at insulating...


you can also put a shut off valve on one of the burners.... sometimes you don't need both for forging small stuff



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anybody got suggestions for him? im reading this thread, very interesting. keep posting svet, hope it works out well for you. how hard is the refracory cement that you just coated? does it seem like it will last long? will the heat expansion of the 2 materials cause it to flake off? is this forge just for heat treating swords or are you going to do forge work with it also? im no expert by any means but if your going to forge with it it looks like all the heat will be in the center, so maybe it would help to have 1 burner closer to the front, and keep the back burner at the same spot???? i dont know... but then there would proboablyl be more scaling right? help us out here guys


is there anyway you can do a test to see how far the flames are bouced from where they contact the bottom of the forge? then maybe you could measure it and place the burner so that the flames just touch the end of the forge???

Edited by JacobE
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Thanks for the replies, guys.


@JacobE, the refractory cement I used is used for sticking decorative refractory wall tiles onto the walls of fireplaces.

It is meant to withstand expansion and contraction. Hope that it will hold.


Actually, I don't rely that much on the refractory cement for holding the forge pieces together.

I intend to wire the froge, so the wire would keep it from falling apart while the refractory cement is there just to fill the gaps.


I will use this forge for heat treating of long Japanese-style blades. This means that I need very EVEN heat inside the forge. No hot spots, no cold spots.

Thus, I need to know the best positioning of the burners for achieving even heat.


Your help is very needed, guys.

I have used charcoal since the first day I grabbed a hammer, so gas forges are a complete mystery to me.




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is there anyway you can do a test to see how far the flames are bouced from where they contact the bottom of the forge? then maybe you could measure it and place the burner so that the flames just touch the end of the forge???

Sorry, I didn't see this question.

Well, I guess the only way to test the forge is drill holes in it... This is what i am trying to avoid. not that I can't tap the holes if it turns out that they are misplaced but still I prefer to ask the experts for the Magic Burner Position Formula. :)


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id like to hear that magick burner formula myself.... and emore i love to hear my ideas critiqued. unfortunately there will probobally be hot and cold spots. most of my small experience has been with a gas forge and even a small one with 2 burners has some. i saw in another post for a long forge about positionging the burners at a slant so that the jets go with the flow of the forge so that alot of momentous energy isnt lost by smasing head on to the bottom of the forge.... waiting to hear from the experts on that one. ive also "heard" but not tested using a small amount of charcoal in a gas forge helps scaling by getting rid of some of the oxygen.



how wide is your opening? it looks like you'll be ok but will the curve of the sword fit well into the chamber? but then again i think that the curve is made by diferential quenching right? still got lots to learn

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The tunnel of the forge is about 15 cm in diameter (about 6 inches).

That is right - in most cases Japanese blades are straight before the quench. The curvature is a result of the differential hardening.


The slanted burners setup sounds quite reasonable. Guess that I will have to put a lid on the rear opening of the forge and positionthe first burner close to that end. The second burner would be in the middle.

Both would be slanted with their openings againste the front end of the forge.

Hmmm... sounds like a good idea, thanks.

let's see what the experts think about it.


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this is just my personal opinion - but i dont think that cold spots are such a big problem.


you are always going to get differences and variation inside the internals of a forge .. even if its just a few degrees ..

but so long as the billet, steel, whatever, is able to heat up enough to get the area you intend to be working on hot ... then its doing good.

afterall .. unless you are using a powerhammer or roller etc then you should keep in mind just how much of an area that you can work on at one time ..

otherwise you are just heating up metal for no good reason.

and its best to avoid that.


thats one of the best things about my f-type forge .. the diameter of the piping means its a small enough area that it can heat an area equal to what im wanting to forge ... and yet it still has the power to heat up an area large enough for my roller to deal with.


and there is a small cold spot in my forge ... but its a nice place to stick the point of your blade when you are heat treating ... that way it tends to not heat up as quick as if it had the full force of the forge behind it.


if that makes sense.


but its up to how you do your forging as well .. and what you really intend to do with it.

if you can work 15" of steel in one heat .. then you will be ready to rock



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Dee, I will use the forge for heat treating only.

heat treating of very long blades (like katanas and wakizashis).

That's why I need even heat and no hot or cold spots.


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It is too late for me to ask more questions about the positioning of the burners now. :)

I just made the first hole.

It is at about 1/3 from the end of the forge.


I used a plumbing PVC pipe with its rim serrated with the edge of a file.





And the semi-finished hole. I used sunflower seed oil to lubricate the pipe and the opening. Thais helps for better rotating and thus - better cutting.





The finished hole. It turned out very smooth, closely following the shape of the pipe.





And the forge sporting the new hole:





Soon I will test the forge with only one burner. If I am pleased with the results, I will leave it like this. If not, I will make the second hole.


To be continued...


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Cool! B)


You have seen Don Fogg's drum forge for heat-treating long blades, right? It does away with cold spots completely. However, since you can't get inswool/kaowool where you are it would be difficult to make. Maybe you could line a barrel with that Ytong brick? It might work, you never know!


Don's drum forge

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What a failure!


I did a double test (or two tests) - I tested my new gas forge and I tested the ability of refractory cement to serve as a coating in differential heating. I decided to go the modern way - no more charcoal, no more messy Japanese clay formulas.


Both tests were unsuccessful.


I grabbed a 1050 Wakizashi blade I had lieing around and coated it in refractory cement (Satanite). Good material, no wonder why many bladesmiths use it - applies easily and you have great control over the pattern. Wish that it worked in the quench too.


I made the clay pattern like this:

On the one side I made a Suguha (straight) pattern:



And on the other I made a Suguha with Ashi + Midare pattern:



Then I wired the still wet Satanite coating to add some support in the quench.




Yesterday the first snow fell in Bulgaria.

I used the situation and put the blade infront of my gas heater - it was there and working anyway, why not use it for my blademaking needs? :)



After the Satanite coating was dried, I fired my new gas forge.

I used only one burner, both ends of the forge were open.

Sorry, I don't have photos of the process - I was too busy cursing and swearing to care about photos.


All I have to say is:

The forge never heated the blade until red hot.

The gas burner's end was the only thing got heated. Oh boy, it got yellow hot, but not the interior of the forge and not the blade! Just the damn burner. It overheated and was ready to melt while the interior of the forge was filled with blue swirling flame and seemed to be way beneath useful temperature. I had the feeling that if I put my finger inside of the forge, I wouldn't get burnt. :angry:


I set the gas pressure to near maximum and waited for 20 minutes. A monstrous roaring could be heard, blue flame was blowing out of the forge but the blade remained at dark heat and never got near Critical temperature. Not even dark red.

I decided to quench it anyway - just to see if the Satanite will hold.

It didn't.

It fell off to the last piece. And it was WIRED, remember?


Here is the blade after the quench:



Yeah, it looks like any other clay coated blade after the quench but I wish that it was hardened too...

Goddamnit, what a failure!


I don't know what was wrong with the whole setup, but I am very disappointed by my first gas forge. Apparently,there was a serious problem with my setup.

Whish I knew what that problem was.


Any advices on turning my forge into a real and useful tool are MUCH appreciated.



Thanks guys!


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Your forge interior is too small. It is burning way to rich. That's why it wasnt getting hot. There is no way you could get an even heat with that forge I.D. and one burner. You basically made a giant burner. I'll bet that was cranking out some CO2.


To get an even heat you need volume so fluctuating tempertures are evened out and the gas has a chance to burn evenly and completely. Well maybe a tiny rich to cut on scale.


Read up on Don's heat treating drum and you will get the idea.


The satanite will fall off or at least some of it. It only needs to be there for an extremely short time.


If you try to treat that again make sure you anneal it real well.

Edited by Hurl Vreeland
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Thanks, I will try to build a new forge, this time with a bigger diameter tunnel.

I don't need even heat any more - seems that it's impossible to achieve. Just any heat.

It is strange that my Ytong forge can't reach Critical... Maybe I should close the two openings at the end leaving just a smal one for the pressure to escape from.

About Satanite falling off - my natural clay and charcoal formula does not fall off. maybe I should add sand to the Satanite?

About annealing - the blade was annealed in a charcoal fire. Seems that it is going back to the charcoal for hardening too.


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A picture is worth a thousand words.

This is the situation at the moment:




Maybe if I put the burner on the thinner wall of the Ytong brick things would change?

Should I stick the burner tightly into the forge's opening so to prevent the fire from blowing out around its tip?


Comments and advices are welcome.

Thanks, guys!


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my 2 cents


if the burner is heating up... the cone of the flame is sitting in the burner bore.......this is not right... the cone of the flame should be in the furnace bore !


-- if it sits in the burner.... it maybe that you do not have enough air/propane speed to sit the flame out further... also... if you have a large flame exiting the furnace... it just tells you that most of the burn is occurring out of the furnace bore....... so you will need more air in the furnace bore via burner...


- a small cone shape burner flare helps to seat the flame in the bore........ from what i understand..... the propane/air travels fast through the narrow tube...... the slows down when it exits the cone flare.... sorta shapes the flame ........ you can make the cone in the refractory as i've done this alot with crucible furnaces..


its not hard to build better burners... matter of fact... its very easy..


heres an example





my self ... i prefer burners with a blower... so you can tune it

-- a simple blower could be a hair dryer with a ceiling fan speed control.....



also...... to heat treat with this style forge.... your going to have to stoke the blade in and out of the forge to even the heat out..... which is tough... .. but a forge like Don's will even the heat out for you..


one last thing...... have you tried mixing charcoal in the satanite... ... i've done this in the past with 36 cement and it worked well

-- also......did you used copper wire to hold it on?



hope that helps abit



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Thanks a lot, Greg.

I didn't get the cone burner part too well. Sorry, my English is poor.

Did you mean I should do something like this?



If this is the idea, then I think it will make the burner get even hotter because it will blow back even more flame. :(


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actually the cone should be the exact opposite of your diagram.. ... with the wide part entering the forge bore...


also......there shouldn't be any air gaps between burner and intake port...


-- but this still will not help the low oxygen issue... that must also be looked at..


i'll look around for a diagram



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What if I put am air blower behind the burner? Guess that this would enrich the flame with oxygen and it will also increase the pressure and make the flame go further inside the forge.


I think I will disassemble the forge and drill the holes on the thinner wall. Are there any other improvements that I should make while the forge is disassembled and while I have free access to its interior walls?



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I just disassembled the forge and then assembled it back but this time putting the opening on the thinner wall of the forge.

I also coned the wall behind the opening giving the flame more space to spread and less chance to get compressed and blow back.




The only problem I see in this design is that the flame will hit the opposite wall of the forge directly and maybe it won't swirl too well.

But I have seen on the net square brick gas forges that worked well, so let's hope that the direct hit would not be such a big problem.


Will see how the new setup performs tomorrow.

I will also try to run the forge with its both ends closed.


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