Adobe stove

[Donkey]

I've recently been turned on to adobe brick for quickly building stove parts.. Adobe is just cob, stuck in a form and allowed to dry.



So I thought that (just for fun) I'd try building the standard rocket J tube out of adobe brick.. Just to add a little twist, I've made a few out of rice hulls and clay slip. These extra light, insulative bricks I've placed in the hottest part of the heat riser, the bottom half.

Here's my usual test bed, showing the adobes in the background.


Here are the two types of brick I made. On the left are the rice hull bricks and on the right, standard adobe.


And here is the J tube stuffed with wood and burning, you can't see any smoke.


It burned VERY HOT. It isn't in this image, but at one point there was flame shooting about a foot out of the top.


After the fire burned down and it was mostly cool enough to handle , I took it all apart to see how the bricks fared. They actually did pretty darn well. The regular adobes bisqued and retained their strength, seems like they could be used instead of red-brick in these stoves, though it's probably too early to really say that.. It was only one firing after all. the rice hull bricks charred through and became very fragile (they were fragile to begin with) though where they were, it might not matter as they wouldn't be getting any impact's etc.. This pic's looking at the char pattern on the rice hull bricks. The brick on the far right there was at the bottom, right in the burn tunnel, so it was getting it from two sides.

Notice the red color.. It's the clay firing and becoming pottery. It's notable to me how well they hold together.

Here's that rice-hull brick broken open to reveal the inside. It's charred through. It took more to bust than I originally thought it might, still broke easy.

[swizzlenutz]

Very cool test. I'm still working on my "cob". So far I have sifted the dirt and added some hand cut tall grass to the mix and now I just need a little sand. What are the dimensions on your form? I'd like to build me one of those. Right now if I leave the bricks outside to dry they will just freeze. I have to find a place in here for them. Swizzle

[Donkey]

The bricks are 10 inches by 5 inches by 2 1/2 inches. Or close to that.
The frame holds those dimensions though the bricks may shrink a little and warp some when they dry.
Wet the frame to make 'em come out of the frames easier, pop 'em out onto a sandy surface so they don't stick. When they are dry enough not to get screwed up, flip 'em onto their sides so air can get all around 'em to dry fully.

[swizzlenutz]

Sounds good. Maybe I'll grab a bag of sand today so I can finish making a test brick(s). Do you pack those as tight as you can or just pack it in and level it off? Swizzle

[josephcrawley]

I recently insulated my cook stove firebox with a 3 to 1 blend of vermiculite and pure clay. Then I lined it with some stainless sheet steel to protect the clay and act as a radiant barrier. I didn't have time to let the clay dry(gotta eat) so I fired it up wet and low in behold a few fires later it had bisqued. It did crack some probably from no drying but this got me to thinking about making my own insulated bricks for burn tunnels. Oh and it really helped my stove heat up faster and use less wood.

Joseph

[Donkey]

Yep.. Pearlite/clay works great too, fine pumice/clay, same, same.
I'm still looking for "an all indigenous, no bought products that any fool can make in an afternoon and is totally reliable" kind of solution.. Tall order, I know.. But it seems worth it to me.

[woodman]

What if I took a 6'' dia. pipe and made a sheet metal 10'' dia. band ,say 10'' tall for a mould that would fit arround the outside of the 6'' pipe.. The band would alow 2'' thick clay to be packed arround the pipe in 10'' tall sections. When the clay is dry take a 14'' dia. pipe and slide down over the clay and fill with wood ash. Could this work?

[Donkey]

Maybe.
You will need to try some tests, figure out the right mix for clay/sand or better yet, clay/grog. You don't want too rich clay content or it will likely crack. In fact, it might surprise you just how little clay really needs to be in it. (It did me)

Wood ash insulation tends to pack over time and eventually stops insulating. It takes a while and works quite well in the mean time. When it finally stops working, the ash can be packed quite tight, just from settling.. I had to dig my home stove out with a garden spade.

[woodman]

I don't know how I could dig it out ash out of a 2'' space.
What could be added to the wood ash to keep it from compacting.

1. How about another layer of clay only this time add some thing to give the clay air pockets?

2. What about after the clay have 1'' space then a pipe then a 1'' space then a pipe. Like the triple wall effect?

[Donkey]

Rice hull/clay or sawdust/clay should work.
The triple wall thing might work.. Dunno how well.

[erniesshop]

Donkey, have you done anything else with this?

[Donkey]

how do mean??
The stove is in my yard, I start a fire in it on occasion; today it's hiding from the rain, under plastic.
I'm impressed with the stove so far but what is REALLY needed is a place to put it permanently, indoors somewhere.
Hopefully by fall, this stove will have a new home. It would be really nice if I can move it in as few pieces as possible and re-assemble in it's new home. More likely, it will need to be re-built to fit the space; though the space itself is not yet built so maybe IT can be designed around the stove... We'll see.

[erniesshop]

I like that you used all free materials.