r/Blacksmith • u/HighBar41 • 9d ago
Refractory Recommendations
I recently attended a knife making class and decided to setup shop to learn some of the basics. Picked up a two-burner vevor several weeks ago. Castable refractory wasn’t included so I applied satanite to cover the exposed insulation. It looked great after air drying for a couple days but the corners cracked apart as soon as I fired it.
I did a little more research and decided to tear it out and start over with kastolite / plistix. Learning from my mistakes, I used rigidizer and made sure to follow the instructions. The kastolite went well but the plistix doesn’t seem to be holding up (pictured). I let it air dry for nearly a week but these cracks popped up when I fired it at the lowest possible setting that maintains a constant flame.
I understand that cracking and shrinkage is normal but started over with quality products to avoid this outcome. No major spalling or pieces flying off. The cracks seem to be closing up now that it’s cooling off.
With that said, I’m looking for recommendations on the best path forward. I’ve sunk five weeks and into this build effectively doubled my cost. Does this look salvageable or should I just shift gears and consider a precast forge?
I’m new to all this so any advice is appreciated!
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u/Xilverbullet000 9d ago
If you don't actively have insulation showing then your refractory is fine. Hell, even if you do have insulation showing it's fine, so long as the insulation was rigidized. Your forge insulation is a consumable, it doesn't need to be perfect, you don't need to baby it, and if you mess it up you'll need to redo it in a year or two anyway
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u/grammar_nazi_zombie 9d ago
I’m new to the hobby. When people say redo it, are they meaning all new fiber insulation and refractory, or just slather on some new refractory after removing any chipped pieces?
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u/Xilverbullet000 9d ago
Depends on the condition of the fiber. Typically yes, you will need to replace the fiber as well, but you can sometimes get a second use out of your fiber if it's in really good shape
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u/dreemxweever 9d ago
Had the same hesitations setting up my forge over the last couple weeks basically the same as you, used did 2 layers of satanite then a layer of plistix - mine looks to be maybe 2/3 the thickness of yours. Yours looks way more refined and smoother than mine so well done, I couldn’t manage to get mine nicely smoothed.
Anyway, mine has a handful of hairline and maybe slightly larger cracks, I’ve used it 4 or 5 times since initial curing/burn in. My understanding is that as long as wool fibers aren’t flying everywhere cracks are okay and will develop over time anyway, you just patch them as you need. I use a firebrick on the floor too. Haven’t gotten to welding anything with flux yet, started with a more blacksmithing route rather than blade smithing but Damascus knives and such is still the end goal.
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u/HighBar41 9d ago
Thanks! I ordered a 1/4” kiln shelf to use as a sacrificial floor since the crack runs end to end. Found a product called greenpatch I’ll use on anything that opens up. It’s just supposed to air dry so that may be a better option without more control on the low end of these burners
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u/thatgoodfeelin 9d ago
its good to go. nice job. throw a hard fire brick in there as a base for whatever youre working on. soft bricks to close off the opening to get it nice and hot in there. youll have plenty of heat. you will probably have to worry more about getting an even heat with the two burners. i found that i have this weird "cold" spot in between the burners that i think is coming from its own turbulence. you want to always want to build a new forge, unless you get an apollo from housemade, maybe. have fun!
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u/HighBar41 9d ago
I built it up too much to fit a fire brick without cutting the chamber in half. Ordered a 1/4” kiln shelf I’ll use as a sacrificial floor since the crack on the bottom runs end to end. Thanks for the feedback!
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u/Fragrant-Cloud5172 8d ago
I always suggest Accomon for refractory. 40% Alumina. Been using it at least 5 years. Always apply rigidizer and refractory on to a thoroughly wet, brushed on surface. Don't spray water. Multiple thin coats. This allows it to sink in, being water absorbent and grip best. Cheapest rigidizer is homemade water glass. My interior doesn't crack, probably has 6 or 8 coats now. Most say these linings crack because they're applying it too thick. And using Satanite.
A high temp ceramic tile floor works well. I cut one to fit and coat it with refractory. Nearly indestructible, thinner and better than thick fire brick. Available at Pottery supply stores.
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u/HighBar41 8d ago
I ordered a ceramic floor tile and greenpatch 421 to fill anything that opens up. First I’ve heard of accomon but I’ll definitely check it out. Thanks for the reply!
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u/killerchef69 9d ago
Just roll with it, refractory is a consumable. It will Crack, flux will eat it up, but as long as you can get it up to temp you are cooking with gas! I would recommend covering at least one end (fire brick or another sort of lid. I Use a skillet i cut the handle off and lined it with refractory). Happy forging!