Recently we gave Gina’s cob hogan a new layer of plaster. We started off by poking at the existing earthen plaster; raking off the loose stuff. It was worn out, but what do you expect after 15 years? All around the base of the walls the earthen plaster had touched the ground. Moisture worked it’s way in. We had to remove about 3 inches in and 1 to 2 feet up in some spots. The wall underneath was still in good shape. We filled in with a stiffer cob mix, rich with sand. We under cut the new cob, rather than plopping it on the ground again.

Day two the plaster mixer and crew ( Megan, Reese, and Amidao ) arrived. Our mix was a little off at first. We experienced some cracking so we augmented the mix. Long straw, horse manure and sand were increased. This performed really well with out any cracks. The west wall receives a lot of wind blown rains here so we paid special attention to that area adding more fiber.

The third day we finished the south wall. We did some sculpting, shaping and repairing of Day 2 cracks. We took sponge trowels and smudged any imperfections out. This left the wall smooth and uniform with small bits of straw revealed. The finish was very attractive.

Our Plaster Mix

2 plaster sand to 1 local clay rich earth
One cup El Rey 200 glue
Two cups wheat paste
Chopped straw - 6 handfulls
Unchopped straw - 1 flake
4 shovels of fresh horse poo
5+ gallons of water

More Photos »

I do. I Love Cob! If you haven’t checked out I Love Cob! - please do.
It’s my blog centered around the magical mixture of clay, sand and straw.
There you will find a collection of photos, stories, drawings, video and tales about MUD.

Kelly, the owner, sculpted a very nice relief on the finish plaster.

More photos »

We’ve been focusing on the upstairs of the earthship, code named Raven’s Loop. We went searching for local earth resources for brown coat plaster. Most of the available earth material is aggregate and large rock. We did find a spot that had small amounts of clay and was just sticky enough to fill some of the gaps in the can walls. The earth is so much warmer feeling than the concrete.

Can walls are a earthship thing. The rough cement and cans surface leaves a nice key for the earthen plaster.

I’ve been working on a earthen wall by my casita.
The barbed wire is visually abrasive so I thought I’d remedy it with some cob.
I’ve been collecting stones and old concrete for the stem wall.
Next to source the mud…

I had some adobes and left over mud from a repair and threw it on the stem wall.
Clay-rich earth, mixed with pit run and straw.

The cob part of the cob wall is starting to take shape. It is left pitted with holes to create a key for the next layer and it helps it dry.

More mud…