Is a ceramic wool forge viable for a first-time blacksmith?

[Asmiralde]

Hello everyone.

I've recently become very interested in forging as I made my first knife using a propane torch. 

I started planning out my forge, probably one with two 3/4 T burners. When I was planning the insulation and casing I was originally going to go with a 13l propane tank for the casing and then insulate it with a 1-2" ceramic insulation and then coat that in a certain refactory. I wasn't quite sure about the refactory as I'm from Europe and it's hard to find here. I would have to contact Morgan about a possible local supplier.

Im usually trying to be very safe when I do projects as such so I have read a lot into the health and safety risk associated with ceramic wool and silica dust from refactories (the refactory being the lesser problem).

I now have doubts about my original design because of the carcinogenic properties of ceramic wool. I would of course use appropriate PPE.

Being safety paranoid as I am, what are the steps I should take after building the forge to use and maintain the forge in a safe manner.

Obviously wearing a respirator and goggles etc while the forge is running is a must. But also after forging (outside) do I need to cover it in plastic or so to keep particles from floating around or is the forge pretty safe after building and whilst not active?

Kind regards 

Stew

Edited June 30 by StewBdo
Forgot an I

[JHCC]

If you rigidize the wool and apply hard refractory, floating fibers aren’t going to be an issue. It’s not going to give you cancer just sitting there.

[Frosty]

It take prolonged exposure to ceramic refractory fibers to cause lung issues similar to mesotheleoma. Once rigidized and encased in hard refractory they can't get into the air to breath. I don't know what kind of refractory you plan on using but the silica based ones aren't very high temperature, they're more suited for fire places or BBQ pits. The better high temp water setting refractories use a calcite based "cement" and are pretty safe chemically. I'm not speaking for all of them of course but you can pull the material data sheet and find out what is in them and avoid the serious health risks.

Frosty The Lucky.

[Irondragon Forge ClayWorks]

Welcome from the Ozark Mountains.

Like has been said once the wool has been ridgidized and cured it is no longer a danger and the same with the refractory. One of the dangers while the forge is running is carbon monoxide (CO) so adequate ventilation is a must and a CO alarm is insurance against CO poisoning.

If you made your first knife with a propane torch, a propane forge is like one on steroids. My wife & I have been using propane forges both in our shop and at ESSA Eureka Springs School of the Arts, where we volunteered in the heavy metals shop (Blacksmith Shop)  for many years without any ill effects.

I can't control the wind, all I can do is adjust my sail’s.
Semper Paratus

 

[Asmiralde]

Thanks allot for all your advice.

I plan to use the forge outside or in a garage with the door wide open. But a carbon monoxide sensor is a good investment for general purposes anyway.

Regarding the refactory, I stumbled across an older thread from another user who was trying to get a refactory in Europe. He ended up contacting Morgan and was able to get his hands on some Arelcrete LC17T (datasheet attached). It seems to be heavier than the regular kast-o-lite 30. Could this be a viable option as a refactory to cover the wool? I have the option of importing Kast-o-lite for a bit cheaper through some friends, but is it worth the hassle?

 I was planning on getting some K26 IFB's as a base in the forge. Would this be a good base or would it reduce efficiency too much? Also, what type of bricks should I get if I need to use Fulx. I've heard it eats through soft bricks like nothing. 

Kind regards. 

Stew

LC17T.pdf

[Frosty]

Looks pretty good to me. It's 63% alumina so it'll be abrasion and caustic resistant, I'd be better (IMNSHO) if it didn't contain so much silica but that's easy to cure with a kiln wash.

I can't say for sure not having any experience with the refractory you're asking about but I do know Kastolite - 30 and it's all and more than I need lining my forge. s

No, I advise against putting bricks of any kind IN the forge. 3/8" or so of that or any hard refractory is all the armor a forge floor needs. Use the K-26 insulating firebrick with a kiln washed flame face for door baffles.

Do you have sketches or pictures of your forge, burner, etc. we can take a look at? 

Frosty The Lucky.

[Asmiralde]

I have some very basic sketches I did a few days ago showing dimensions and such (attachment).

For the burners I will follow your design from the PFD. Im just going to attach a gas shut off valve and a gas hose which is connected to a splitter (to supply both burners).

Im still a bit unsure about a few things such as what angle to put the burners at so they point towards the base of the forge and not the corner so as not to put stress on it. Also how should I attach the burners to the forge. I dont have a welder and most examples Ive seen have a fat tube welded to the forge with a 4 screws holding the burners inside. 

Ill be using two burners so a 30psi regulator should be good enough? 

In the T-burner PDF it says that if the burners get too hot you should have copper tubing leading from them. I dont plan on doing this any time soon but if I forge weld do I need such copper tubing because of the heat?

What should the ends of the burners look like when inside the forge? I see the original design uses a thread protector. Is this used while in the forge or do you just attach the 6" pipe to the forge and use the edges of the hole as the last piece?

The little bit of extra refactory I plan to put on the base of the frog should be ok? Or would it reduce efficiency? I plan to cut out the two round sections of the gas bottle and put two bricks in front of the openings to regulate pressure and heat. 

The sketches arent well made as I wasnt at home while making the but the measurements should be correct. I did also translate cm to “ for you guys.

Kind regards 
Stew
 

[Frosty]

I can work with your drawings. Did you take drafting classes? I stopped using the radius for dimensions on circles, it confused too many folk on the forum. 

There's nothing I can see that won't work in your drawing. Is the floor going to be wide enough for what you plan on making? 

I made and generally suggest using the refractory blanket to make the floor. I cut a piece the width of the floor and feather the edges so it rests on the curved forge bottom with a flat top. Make sense? Then it gets rigidized and the final refractory layer like the rest of the forge.

This does a couple things: 1st. it increases the insulation under the floor. 2nd it weighs less. The increased insulation where the burner flame impinges means it heats up faster and helps prevent the damage caused by getting refractory blanket as hot as our forges do. Yellow heat tends to melt most refractory blanket but worse it vitrifies it making it brittle like glass and any particles have broken glass sharp ends. This is what rigidizing helps prevent getting into our breathable air.

There are a number of plans for aiming the burners but I don't see anything wrong with yours I might lower the burner port(s) so the flame meats the floor at a shallower angle but I don't build tubular forges. Mikey is better aligning burners, I prefer rectangular forge chambers.

I'm having a little trouble reading your dimensions but it looks like you are planning a forge with a little more than 1,000 cubic inches which will require three 3/4" T burners to bring to welding temperature.

The ID looks to be about 8" and the length about 18". That is a VERY large forge, what are you planning on making that requires heating 18" of stock? A person can only forge about 6" at a time before losing heat unless they have a power hammer or forge rolls. 

Please don't take it wrong, I think virtually everybody makes a WAY too large first propane forge. Happily I made my SILLY too large shop forge so I can divide the interior easily. The 18" square top lifts on a jack so I can arrange insulating fire bricks to make the size and shape chamber I needed. Sound pretty good? Wellll, I discovered that 90+% of what I did fits in one 4.5" x 4.5" x9" section nicely and if I wanted to heat a long section say to twist or bend I simply angle the half brick separating the section I'm using from the next inline so I can move the stock back and forth.

The only time I've lit all 4 burners after testing it was at a couple hammer ins where 5-6 people were working at once. Boy was that a bad idea, there were only 3 anvils and not nearly enough room so we were constantly surrounded by burn hazards beyond normal blacksmithing.

Anyway, I build much smaller forges though my current one is almost as long as yours though about 1/2 as wide and high as the diameter of yours. I find myself putting a brick partition in it to use one end. 

Using copper tubing as the final fuel supply circuit is an individual choice. The way I make a T burner means the brass fitting that holds the mig tip jet and connects to the supply line doesn't have many threads holding it in position and because they're tapered they bump out of alignment easily. Also my too large shop forge has really HOT exhaust gasses though the dragon's breath isn't as bad as it looks. I found it gets so hot on top propane hose was degrading too quickly.

Copper tubing took care of it all. Once bend to reach from the propane manifold to the top of a burner it applies almost no sideways pressure on the gas jet. And it doesn't matter how hot the copper gets, by time it reaches the burner the propane has cooled enough it won't pre-ignite so the burners perform properly. I don't know if any of the copper gets hot enough to pre-ignite propane but it is discolored by heat so maybe. What is for sure is 4 rubber hoses would be constantly trying to knock the burners over and suffer from the heat.

You don't need to weld burner mounts to your forge. Simply cut the pipe at the angle that aims the burner flame where you wish and fits tightly in the forge shell. Then drill (3) is a good number 2 is too few, of angle iron or bent steel tabs. Position the sleeve where you like it, mark the tab's position through the holes on both sleeve and burner shell. Now drill and tap the holes and use machine screws to attach everything. 

Sure it's more work and harder to get everything right but it works nicely. Self tapping metal screws work but it's hard to keep them in position while they drill. I've had good luck drilling the holes and using sheet metal screws, they're plenty strong if you don't knock the propane hose around. My propane tank is in a NO GO zone, I yell at anybody who even looks like they're going to violate the zone.

I hope my long rambly post answers your questions or at least narrows them down. Please feel free to ask more, I'm happy to help folks get these things working.

Frosty The Lucky.

[Asmiralde]

That helped, thank you.

A few more questions.

For the Ceramic Wool Rigidiser. How much do I need? I think I read somewhere that you should brush some water on the wool before spraying on the rigidiser.

Would it be possible of you could explain how to reattach the burners. i dont quite understand what i have to do with the angle iron or what is meant by sleeves and cutting the pipe at an angle.

Im currently on holiday using my phone as a ruler and planning the forge to perfection so when im home i can build it safely and know what im doing.

Kind regards 
Stew

[Frosty]

Be happy to. Wetting the ceramic blanket is called "buttering it" It's a masonry term. What buttering does is it prevents whatever you are applying be it mortar to bricks, tile, etc. from flash drying the mortar on contact. That leaves a thin layer of dry mortar between the mortar and the brick so it doesn't make a good bond. Buttering the brick, rock, ceramic blanket causes the mortar to dilute on contact and it runs into the pores of a brick or flows along the fibers in the refractory blanket. It collects at intersections and remains when the blanket dries.

When you fire cure the rigidizer the silica melts and fuses the fibers together. The fibers in the blanket don't melt but they're coated in silica that melts and sticks to to everything.

If you've ever messed with molten glass you know it's some of the stickiest stuff around.

I've bought rigidizer and boy was it expensive and had a short shelf life. What most of us use now is colloidal silica powder. Colloidal meaning it stays in suspension in water once mixed. I bought mine at the local plastics supplier but you can find it at masonry suppliers. It's used to make material thicker, say you want fiberglass resin to stay where you put it on a vertical or overhead surface without runs and drips. You would mix the silica powder to the resin until you got the consistency you wanted, then add the hardener and apply it.

Another common use and why you find it at masonry suppliers is it's used to thicken plaster. If you've ever seen the ornate moldings on crown moldings, arches, etc. and wondered how they got it to stay put without sagging, they thickened it with colloidal silica.

Anyway, that's what most of us mix with water and spritz on our refractory blanket liners and as far as I know I don't think you can overdo it. Please don't take that as a challenge, I'm sure it's possible if a person tries. 

When I'm rigidizing I use two different colored spray bottles and add a couple drops of food coloring to the one with the rigidizer so I can see the coverage when I spray the refractory blanket. How much did I apply? It was running out of the drain holes in my forge's shell. I soaked it and soaked it good. 

I let it dry a day and used the forge burner to bring it to red heat. Rigidized refractory blanket is stiff but not hard. The hard refractory inner liner (flame face) is concrete hard.

When you build your burners, T or other, don't put the 1/4 turn shut off valve on the burner, put it in a place out of the heat. If something goes wrong and you have to turn the burner off faster than turning the propane tank valve off and waiting for the supply lines to bleed you might not want to reach through flames. The valve and fittings to make up to the mig tip and propane hose are also a lot of weight hanging off tapered pipe threads.

I've discovered the less weight I have attached to the burner the better they work.

This post has run too long as it is. I'll answer your questions about a no weld burner mount. I'll even use graph paper and make a couple sketches to hopefully make it clear.

Frosty The Lucky.

[Asmiralde]

I really appreciate all the help you've given me on this topic, but once again specific questions have arisen.

How much water should I use when buttering the blanket? Should I soak it or just give it a fine coat?

As you recommended, I will be using collodial silica for my rigidizer. I had a quick look around for the ratio with water but I didnt find anything that would assure me (granted I only looked for about 10min). How much collodial silica do I need for a froge of my proportions (shown in earlier post). I had a look around and found West System 406-2 Collodial Silica it is sadly only 1.7oz which im going to assume is way too little. I attached a SDS and and another from of datasheet belonging to the silica it should be correct from what I’ve seen and the descriptions I’ve read of it on amazon but you can never be too sure when it comes to safety.

Regarding the refactory I luckily found a shop in Germany that sells Froge cement rated at 1600C (2912F). It looks pretty good, has about 80% alumina and 7% silica. 
I had to email them for a datasheet so most of the stuff is in German but its pretty self explanatory I belive (attached below).

In the post above you mentioned that the more weight the burners carry, the worse they perform. Im not quite sure how to solve this problem as I was going to run about 1 meter of gas pipe from both burners into a Y connector. One option would be to put the shut off valves on the Y splitter, but that would still be weight that would affect the burners. I dont really know if im going to have the forge on a table or on a stand etc. so I cant reliably attach the y connector to something to ease the weight on the burners.

Now that my forge is smaller im considering not cutting both ends of the forge but cutting off the front and then reattaching it with a hinge and making holes in the front and back. It could be better insulation and if I have something bigger to forge I can just open the door and use fire brick to cover the entrance to a proper amount. I saw a post about the size of openings on a forge on the Gas Forges 101 thread, I did not read all 90 pages but I dont think an exact value or ratio was given to estimate the size of the opening. I improvised a bit and made an opening that I think makes the forge look cooler but still gives me the custom opening option by opening the door and using bricks. I drew a sketch of the size of the opening (see attached). 


This post was also very long, but I think its better to ask than to fiddle around with dangerous materials. 
And again, I really appreciate you taking the time to help and answer questions.

Regards. 
Ben

 

 

406-SDS.pdf WEST SYSTEM 406 TDS.pdf

[Frosty]

Join the club, everybody wants specific ratios, quantities, etc. when doing this the first time. I don't think there are any, I don't know them anyway. Excess water literally drains out of refractory blanket, it isn't absorbent like a sponge or paper towel. If you put a few drops of a wetting agent like "Finish" dishwasher soap helps a lot. Same when mixing the colloidal silica. I don't know what you have available but it only helps it isn't necessary.

I suggest giving the blanket a good wetting with a spray bottle, if water starts running out of the bottom of the forge shell it's more than good.

It's been a few years and my memory stinks so I can't say how much colloidal silica I used but I added it till it started interfering with the spray bottle working, then added water till it stopped plugging the sprayer. I can't say how much the spray bottles hold even. I bought a bundle of 4 at a big box department store. I'd guess about 20oz, say 600 mil. and I'd have to guess about 1/4C. or less say 60 mil.

By eye, add the silica until the water won't hold any more and add some water till none settles on the bottom. 

Mike has more precise numbers for this, maybe he'll join in. 

I sprayed the entire bottle on my forge's ceramic blanket, keeping the color even. When water stopped draining out the bottom I lit the burners till the blanket glowed red. 

West Systems 406 is good stuff. The BIG thing to watch for when buying colloidal silica is whether it is hydro-PHILIC or hydro-PHOBIC. You want hydrophilic, it "likes" water and mixes easily. The hydrophobic silica doesn't mix with water without extreme mixing!

Get HYDROPHILIC colloidal silica!! It is IMPORTANT.

When I said your sketch of a burner build had too much weight on the mig tip jet. I was referring to all the plumbing, a sub to connect the brass fitting and mig tip, the valve, 90* elbow, to the hose. The top of a T fitting is actually darned thin, maybe 1/8" thick. This isn't much metal to thread and support the weight of the fittings and especially the hose it can bump the propane jet off center in the burner and degrade performance. The propane hose is the most susceptible to being bumped and it weighs quite a bit. 

My burners use a brass 1/4" MPT "Male pipe thread" to 1/8" compression fitting and 1/8" copper tubing to the manifold. From there to the tank is the hose, the regulator and gage is on the tank. I run off a 100lb tank and it's close enough to the forge nobody wants to walk between them. 

The copper tubing is bent to end at the position of the burner's top and actually helps support them. I started doing it this way on my silly too large shop forge because the top of the shell is thin flat sheet steel and tends to warp when the forge is running. I don't put flares on my T burners and the ones on the big forge just screw into "female floor flanges". These are the fittings that you'd anchor in concrete and screw pipe into to make a railing or similar. picture below. They just sit on the forge, screwing them to the top shell didn't work, the warping tore the screws loose. Anyway, the copper tubing keeps the burners in position no matter what the forge shell does.

The point is, the lighter the weight and less leverage the propane supply has on the jet mount fitting the better the jet stays centered down the center of the mixing tube. And centered is the most important thing to get right for proper burner performance.

Frosty The Lucky.

[Asmiralde]

I think I am coming to the final stretch of questions.

I was looking for a better description of the exact process of rigidizing on the homemade rigidizer thread and found one of your old explanations on how to properly use the refactory. One thing I did not quite understand. Do I need to flame cure the first outer layer of ceramic wool? Or do I just need to do that step for the inner layer? Do you happen to have an approximation of how long the rigidizer needs to cure?

To attach the burners, I think after your latest post I understand the description you gave in an earlier post about how to attach the torches. I have drawn a sketch that I hope you can identify.

One thing i am still not so sure about is how big of a hole should be for the burners you mentioned above that should fit tightly but is the just of the metal shell or also for the refactory and ceramic wool layer? So should I carve a kind of reducer shape into the ceramic wool or is it fine to be tight? I also made a questionable sketch below.

I believe these are my last questions until I build my forge. I really appreciate all the info and time you have given to this thread.

Ill probably post a pictures or more questions before and after the forge is finished.

Regards.

Ben

[Frosty]

That is what I was thinking for tabs to mount the sleave for the burner. 

Yes, I flame cure the blanket in the outer layer of blanket before inserting and rigidizing the inner layer. It may not be necessary to encapsulate fibers but making the refractory blanket stiffer makes it more structurally sound and the hard refractory flame face less likely to crack or spall. 

AND we get to the burner ports, I don't use a flare on my burner nozzles I use a thread protector which is one of those things you have to sweet talk the guys at a plumbing supply out of, it's not legal to sell them. They are only to protect the threaded ends of plumbing pipe during shipment. They resemble pipe couplers but have no structural strength and could fail disastrously if used instead of a coupler. 

Anyway, I started using thread protectors welded to the NARB plenum so I could screw a T burner to it directly and darned if it turned out they make a nearly perfect nozzle. I can fill the threads on the output end with Kastolite refractory with the aggregate sifted out to protect the nozzle from the heat and they last well.

All that said they're about 1 1/4" OD IIRC. I use a hole saw the same OD to drill a hole in the shell insert a thread protector to the depth I like and weld it on. 

Others use bell reducers and have to use a different method.

Before the hard refractory flame face liner is fully dry I drill the forge liner, through to the interior. While the hard liner is still green (not completely dry) it can be carved and I open it to about 1 3/4" or so and shape the port into a cone shape. Then I spray and cure the cut refractory blanket with rigidizer to encapsulate the now broken fibers. Lastly I apply a thin coat of Kastolite 30 hard refractory to make it smooth and flame proof. The trick is making sure there is room for the burner nozzle in the burner port.

I do it differently than others recommend, Mike likes a little air gap between the burner and the refractory liner for a couple reasons. 1st it provides extra combustion air to the flame and secondly it helps keep the burner nozzle cooler. 

I THINK I got that last right, Mike will jump in if I didn't.

If you use a sleave to hold your burners there are several advantages besides the air gap. It allows you to adjust your burner's depth and alignment, even while it's burning if you wish. The sleave is a piece of pipe your burner will slip through easily. It has holes drilled and tapped at 120* intervals for set screws. Two rings of set screws allows very precise adjustment by loosening one screw and tightening one or two on the far side. Using all 6 screws makes it easy to get silly accurage directing the flame where you wish. Make sense? 

If you use the tabs I described to mount the sleaves I forgot an important detail that makes it all tight and solid. Mark the location of the tabs and center punch the hole locations in the forge shell. When you drill and tap the hole in the burner mount sleave drill it a mil or two high. Screw the tabs to the sleave first and when you screw them to the forge shell it will pull the sleave down HARD against the forge shell when the screw closes the 1-2mil gap between the tab and shell. Make sense?

Hopefully I haven't raised more questions than I've tried to answer but please feel free to give a shout out if more arise. One of the reasons I hang out here is I like helping folks get going in the craft.

Frosty The Lucky.

 

[Asmiralde]

This is gonna be very brief.

Is there any reason this (attached) reductiondoublenippel shouldn’t work as a replacement for the 1/4 flare x 1/8 mpt union ?

kind regards

Ben

[Frosty]

I don't know, what are your plans for it? If you're going to use copper tubing the part that threads into the T has to have an ID that can be tapped to receive the mig tip's threaded end.

It's hard for me to say what will work in another country there are often differences in how fittings are measured so I'm never sure. There is also variations in fittings made by different manufacturers and it's gotten very odd since China started making most of what we can buy. I started taking my tap to the supply to see what would work. 

Frosty The Lucky.

[Asmiralde]

Another quick question regarding flame curing the ceramik blankets.

I do not own a bernzomatic torch. Is it ok if I just use one of the burners on medium setting (held with pliers) to flame cure the insulation. I understand you just need to get it to red heat so the silica will melt.

Regards.

Ben

[Frosty]

That will be fine, I've never used anything but the forge burner to cure rigidizer.

Frosty The Lucky.

[Asmiralde]

Hello everyone

I've successfully built my forge. I am now at the stage where I am testing my burners. Unfortunately, and as always, there's a bit of a problem.

They make this clicking sound. I have attached a video file.

Other than that its gone very smoothly and im happy to have finished the forge.

[Frosty]

Your burner is tuned very much too rich, the sound you're hearing is the flame burning in the mixing tube in small detonations when enough combustion air is induced to reach a combustible mixture. The little pop (click) increases the pressure in the tube enough to prevent enough combustion air to burn so the flame goes out instantly and more air is induced. inhale, pop&go out. inhale, pop&go out. inhale, pop&go out.

At this point I believe your gas jet (mig contact tip) is significantly too large. It is putting more gas in the burner than can burn with what air it can induce behind it. Rich means too much fuel to air. Lean means too little fuel to air. 

The shape and color of the flame in the forge chamber is all you need to see to know it's running WAY rich. The sputter is a symptom of extreme imbalance if fuel air ratio. Sooooo, there is no need for movies, a still pic of the flame is more information than the sound. 

I suggest you try the next size smaller mig tip and I'll talk you through tuning it when it's close enough to fine tune. 

Frosty The Lucky.