Benjamin Dinkel

Hi Mike,
what about a recycled old shower pan? Or bathtub?

I would highly discourage anyone from using tadelakt or polished plaster in horizontal areas where water remains for extended periods. Also a floor is subject to abrasion. It can potentially work with constant upkeep but it’s not user friendly.

I agree with Thomas and Kevin.
An option could be to insulate the jacket itself and the flue pipe.

Thank you Daniel for your insight.

Sure, the necessary air channels would be built into the frame of the door. And the whole door and frame unit would be leaning against the core. I hope it will be airtight enough. I’ll see what I can come up with.

Good news that you’ve built BBRs with just cob as framing. Do you have experience with the shorty too?

And a new question: did anyone try refractory shelves (kiln shelves) for the roof of the burn chamber of the shorty? Most I’ve seen are self cast refractory.

Thanks in advance

Hi Carla, a nice thought experiment. But I think the downsides are immense. Specifically the necessary handling and drying of the material prior to incineration.
What are the arguments again using a Jenkins style dry toilet with hot composting using a couple of buckets? That way you can always have an empty bucket in the middle of the night or when you’re sick. With minimal interaction and a great end product.

There’s definitely a maximum of pressure loss (that translates to a maximum length of pipe and number of turns). But it depends also on what rocket you want to build.

Hey Mike. A rough sketch would help.

From what I imagine it sounds like very little heat exchange surface (inside of the pipe) to a lot of thermal mass. That would mean the mass never gets hot.

Hey, thanks for clarifying. The flour is essentially for structure in the mix I imagine. A lot of lime paints use fine sand or other powders for that. In the combination with linseed oil I can’t imagine a lot of problems. But I haven’t used it, so I can’t vouch for it. You could try a patch and worst case sand it off if it discolors in an unwanted way.
Please share your findings! And good luck!

Hey Tiffaney,
I’m struggling to understand what exactly you’re asking, I’d like to help.
What is it that you want to paint? A cob bench?
What exactly is flour paint? And what are you trying to achieve?

For a while now I've been pondering a BBR for my home.
I want to build a 6" BBR with a bell, possibly as a bench.

I really like some of the features of the 7 inch batch box rocket mass heater in the woodshop at wheaton labs such as:

gravity plunge door

no metal bracing used, but cob holds the core together

I'm wondering whether the plunge door could be implemented on a "Shorty core" if the necessary air channels are built into the frame it leans against.
I like that the Shorty doesn't rely on the secondary air channel that needs replacement.

Could the "cob" bracing work on a shorty core? Or are we entering weird experimental ground here?


Thanks in advance fellow RMH enthusiasts