Will SE Montana Gumbo work for cob?

Anyone every been stuck in mud? Not like the "gumbo" mud of South Eastern Montana I will bet. Anyway, my question is this:

1. can I use the gumbo (bentonite?) to use as the clay part of cob? True bentonite is volcanic ash of 100 million years ago that has gone through some chemical processes of pressure and time to become the material of drilling mud. True clay is a sedimentary material laid down in ancient oceans.

2. Has anyone made cob from gumbo? In constructing our rocket mass stove heater for my friends 100+ year old homestead last weekend we mixed some gumbo and sand 1:1 ratio. It seemed grainy, not smooth like pottery clay, but held together. We didn't add straw as we only wanted to plug up leaks to test our stove (several times as we didn't have the correct CSA, which we found here later in the forums).

3. Anyone ever try firing the gumbo clay for pottery type purposes?

4. A little off topic, but has anyone tried using old bailing twine instead of straw in the cob? We didn't want to use this next to the rocket stove where it might melt, but were considering "recycling" the piles of used twine on his ranch for the mass in the heater portion of the stove.

1. can I use the gumbo (bentonite?) to use as the clay part of cob?

Yes

Do some test batches always when unfamiliar with a clay source and it's characteristics. Empirical knowledge is priceless.

True bentonite is volcanic ash of 100 million years ago that has gone through some chemical processes of pressure and time to become the material of drilling mud. True clay is a sedimentary material laid down in ancient oceans.

Not all Bentonites are the same or have the same firing/drying characteristics.

2. Has anyone made cob from gumbo? In constructing our rocket mass stove heater for my friends 100+ year old homestead last weekend we mixed some gumbo and sand 1:1 ratio. It seemed grainy, not smooth like pottery clay, but held together. We didn't add straw as we only wanted to plug up leaks to test our stove (several times as we didn't have the correct CSA, which we found here later in the forums).

Define CSA? so I'm clear. and again each clay is different, testing is a must, it would be hard to give you a set formula to use without being there. Your on the correct track, just test batch some different ratios.

3. Anyone ever try firing the gumbo clay for pottery type purposes?

"Gumbo," is too generic to have an applicable answer. Yes I have fired Bentonites up to cone 11 which almost made a nice porcelain, but others can explode, again you have to test the batch the run of clay you would want to fire and probably add other clay types to it to achieve a good "body," and also know what your goal is...stone ware for example.

4. A little off topic, but has anyone tried using old bailing twine instead of straw in the cob? We didn't want to use this next to the rocket stove where it might melt, but were considering "recycling" the piles of used twine on his ranch for the mass in the heater portion of the stove.

Works great, as does any long fiber source, in most cases, including human/animal hair.

Regards, jay

Jay,

thank you so much for your input. It is especially nice to know about the recycling baling twine.

I understand the part about different gumbos. That in Texas is way different than ours in Montana. My next step before adding the mass to the stove is to do the quart jar test, allowing the sand to settle first, then the silt, and last the clay and find out what percentages I have in our test sample.

BTW, CSA = Cross Sectional Area, which should be about equal from intake, to burn chamber, to riser. The riser being 6", pi x r (2) = 28.4, so we had to make the intake and burn chamber about 4.5 x 6 inches. When we did, boy did it "rocket"! Also, discovered the length of the intake and length of burn chamber has to be less than the length of the riser. We are now going to have to experiment a bit to find out what it will take to burn coal, as my friend has a seam that the original homesteaders used to keep warm in winter. The increased heat may mean that the riser will have to be built out of fire brick to keep the riser from melting!

Not planning on making any earthenware, was just curious if anyone had, especially from our area. Never hear of anyone doing it, so volcanic ash content may be too high/low.

Thanks again for your response. Would love to meet you if you make it out to Montana. Unfortuneately we have few trees for an arborist to look at! But there are lots of prairie dogs to act as targets. Figure an ex-Marine might enjoy that.

Hi Dale,

Thanks for the invite, I hope all your test work out. Pictures of your projects would be great. Living traditionally, and my heritage, I don't kill anything I don't either eat or feed to something, (which was a bit of a running joke in the Marines.) Besides I wouldn't want to deprive any Black Foot Ferrets a home or meal. I do miss eating Prairie Dog, they are tasty.

Regards, jay