Consider using an 8"x 8" square of Morgan superwool.
Water glass (sodium silicate) will glue the wool to your barrel directly over the riser.
This should eliminate the super hot spot, yet still let plenty of heat thru quickly!
If this sounds like something you would like to try, PM me your address and I'll send you a square of super wool for the shipping.
The advice from Paul was to clean out all those piled up flakes, as they are creating an insulative layer and thus making the situation worse. If there are no flakes, the heat can dissipate into the oven better, and the metal won't get quite as hot and maybe won't spall as much.
Thomas, I think your idea is terrific, and I would love to take you up on your offer. I'm not sure how to access the spot, though. The heat riser is cobbed onto the barrels, with hardware cloth reinforcing the cob.
I asked Eliot if there's a way to access from the back, because you can open the barrels up there, but there's a wall in the way.
Stainless steel would spall in that location, too, unfortunately. The temp at the top of the heat riser is going to exceed the working temp of any [affordable] metal alloy one could use there. (Inconel or 330 series nickel-stainless might work, but the cost is just *outrageous.*
One thing that might help would be to use high-alumina castable refractory — and coat the inside and outside of the barrel wall in that spot. The spalling itself is a result of oxygen attacking the metal when it’s white-hot…causing those oxidized chips of metal to flake off. In theory, if you can prevent the O2 from contacting the metal, then the spalling would be mitigated.
Edit: I didn’t see the 2nd page button of this thread. My post was meant to reply to Greg’s post at the end of the first page:
Greg Martin wrote:Do you think it would be hard to find a stainless steel inner drum that size? Otherwise, I wonder if an internal stainless steel bent sheet deflector would work to help distribute the heat a little to help eliminate the focused hot spot and avoid the spalling?
Hi Julia, do I understand correctly that you bought this oven and moved it to your farm? How did you move it in one piece? Isn't is super heavy and not to mention awkward? What was needing to be finished after you bought it? What is the oven part made of? Are plans available to follow to make another one like it? I don't mind the 'ugliness' as long as it functions well. Thank you for sharing your creative way of decorating the front of it. It turned out very nice.
Location: Moved from south central WI to Portland, OR
Hi Denise! The oven came in a van, it's about as heavy as two 55 gallon steel barrels, so, too heavy for *me* to lift, but not too heavy for a couple of strong men to lift.
You can watch a movie about these ovens and you can buy the plans as well. The links to both are in my post right above yours in the thread. (This thread has gone to multiple pages, which can be confusing.)