Vincent Musser

Also, could my clay simply be in need of a lime wash once finished to hold its surface in tact from normal wear? (Never tried lime wash)

Well, I can tell you this about my clay:

When I work it over with a trowel, I am able to pull moisture out of it, then let it dry a bit, and repeat, just like finishing concrete. About the best that it gets once dry after troweling is very smooth, but no sheen at all. I had assumed that a good sand\clay mix would dry this way.. but maybe I should be seeing a good sheen on it once all dry?

And thanks for the help!

I had about 1\4" of newspaper\clay slip on this barrel. It popped off after maybe 10 minutes of hard burning. I had the rocket effect going for a bit with the old duct I threw in there.. first time to hear it in person! Baby, I'm ready! Sounded nice.

Here it is now after 10 hours. Looks like about 1\4 clay to accumulated sand and silt. I know from my test bricks that any more than 1 part builders sand to 4 parts of this earth becomes crumbly. I think this stuff is right on the edge of having a perfect ratio dug right from the ground.

Just did the test with a masons jar. Here is the photo after 10 minutes or so. Arrows indicate first heavy sand, then the lighter sand that came down after 10 minutes. I am guessing all the water-born brown is clay?

Allen, I have done this test twice, with the jar and water. Both times it has taken a good 12 hours or so for the majority of the material to settle. I will play around with it a bit more just to make sure. I think most of the sand from those bricks was coming off the higher sand ratio ones. The one that I used 1\4 sand to 1 earth was pretty tough. Then it went the whole way to 1 to 1 and that was very crumbly. I will test more though, with larger jars. I had been using a small amount for the jar test.

allen lumley wrote:V.M. Remember to save 1 1/2'' - 2'' for your structural cob, the stuff with the straw, and your final waterproofing finish coat ! Big Al !

Do you mean in general, as I never showed these layers in the drawing? If so, I was just planning to have the outermost 1.5" of cob on all the surfaces to have chopped straw in them. This refers to the outline of the bench\cumbustion unit shown in the drawings.

Then, I was planing on adding 1\2" of earth plaster to it all when the rough cob is finished. Didn't show this on the drawing, but I expect it to "grow" 1\2" more all around once finished and lime-painted.

Also, I am planning on using "form boards" to build this thing. I want to use 1\4" plywood and templates to shape it all. Will this create any problems for the earthen finish plaster adhesion? I wonder if cob with a plywood formed surface could be to smooth for earth plaster to stick to. If so, will scratching the surface of the structural cob be enough to promote earth plaster adhesion? (One of those worries that won't leave my mind all day)

Thanks

Ahh, clean it from the top, no ash pit needed.. got it.

My barrel does have a removable lid, but I was contemplating doing the extra work to use it that way. Now I have a reason.

I am wrapping the barrel with clay slip and newspaper right now, getting ready for the first burn..

Thanks

Thank you Allen.

This is all great! Another core will be born soon..