100 lb propane tank sword oven

[Johnathan T]

In short, I've considered my options (I can explain if you want), and I'm planning to make a vertical sword oven using a 100 lb propane tank as the shell. Video 1, Video 2, thread. I don't plan to make it electrically controlled. I want to get swords up to critical temperature for normalizing and the quench. If I can temper them too, that's a bonus.

There are some things I want to ask about/confirm. This group suggests 2 inches of kaowool for forges. I assume the same goes for this oven. It would be nice to not have to worry about airborne fibers (I'll wear a respirator if there are), but it would be difficult to apply rigidizer or castable refractory the usual way because of the size. Because this is an oven, I don't think it needs castable refractory. I think I could only use rigidizer and be safe. I think the rigidizer doesn't harden the kaowool immediately, so I think I should be able to apply rigidizer to the pieces while they're flat, then bend them into the shell and let the rigidizer dry/cure. I've read that a gallon of rigidizer will make a hard surface (but not a hard hard interior) on 25 square feet. If I were to rigidize both layers completely, it would be a lot of rigidizer, and I don't know if that would be necessary for this application. My guess is that if I were to harden the surface of all the exposed kaowool, I would be safe from airborne fibers. If that won't work, how do I make it safe? As for ITC-100, it would be a lot, I don't think I could apply it because of the dimensions, and I don't think it's necessary for this application.

I have problems with my coal forge, and have been wanting to switch to propane. I thought that while at it building the oven, I could finally build a propane forge from a 20 lb propane tank. I won't be using the forge and the oven at the same time, so I considered buying one high quality burner (rather than 2 cheap burners) and moving the burner (held in with thumb screws) between the forge and the oven as needed, and eventually getting another burner if I think it's worth it. I was thinking of getting a 3/4" t-rex burner for that.

[ThomasPowers]

So have you talked with many professional sword makers to find out how they are doing it?  Perhaps talking with them about how the did it getting started?  Profit from the mistakes and bad assumptions of others!

[Johnathan T]

Thanks, that's a great idea! I haven't. I didn't think about it because I don't know how.

[ThomasPowers]

Search out folks making custom swords; many will have contact information.    I wonder what the American Bladesmith Society school in Texarkana uses.

[Yanni Rockitz]

Jonathan -- how'd this go? I suspect you've figured it out by now, maybe? Curious what you did and how it worked out...

For what it's worth, 2" of ceramic fiber blanket -- each rigidized, dried/cured separately, so that layer 1 is 'rigid' before adding layer 2 is the ideal solution, but you can also get away with just rigidizing layer 2, then coating it with refractory. Instuff Rigidizer is a good pre-made colloidal silica rigidizer for the money -- works great -- two quarts will more than cover two layers for a 20lb propane tank gas forge. Paint it on with a little cheapo 2" brush. I cut most of the handle off a wooden one so it's easy to manipulate inside the forge.

• Rigidize, air dry 24-48 hrs
• Low burn for a minute, let cool, low burn again for five minutes, let cool, low burn for 10-20 minutes to really cook it in.
• Add the second layer of blanket, rigidize using the same drying/curing process
• Refractory coatings:  Either two 1/4" layers of Kast-O-Lite 30 (~1/2" total) or two ~1/8" layers of Satanite refractory covering all exposed blanket. Kast-O-Lite is way more flux-resistant, if you're forge welding. I did my forge bottom and halfway up the sides with two layers of Kast-O-Lite 30, then two layers of Satanite over everything after that -- finished with two painted-on ~1/16th" layers of ITC-100. The forge gets crazy hot.
• You REALLY want to make sure to follow the drying and curing instructions diligently. Air dry in warm, dry air at least 24 hours, then the successive low burns until steam appears - OFF - let it cool, repeat, longer each time up to full operating temps. If you rush the drying process, it'll fail -- the steam will blow apart the refractory structure, if 'boiled.'
• NOTE:  Kast-O-Lite has to hydrate and cure in a 100% humidity environment for a good 24-48 hrs, so wrap a wet towel around the forge and tie it up in a trash bag to let it sit that duration. Once cured, air dry, then cook it at 200 F in an oven for a couple hours, maybe another hour at 300 to really dry it out, let cool, then the low burn cycles to fully cure.

It's a lot of long, slow dry times and burn cycles, but you'll have a way better lining that'll get hotter, be more fuel-efficient, safe and last way longer. ITC-100 is stupid expensive and there are cheaper alternatives, or so I hear. Greenguard, maybe? It's in this forum...

Hope it's all going well!

[Frosty]

Nice job on your forge Yanni. How's it working for you?

Frosty The Lucky.

[Mikey98118]

I like the yellow incandescence shown within the forge, but am not crazy about all that blue flame exiting it.