Slip Coat on Fist Wall Section

Our marvellous mud makes magnificent render!

This first coat is primarily to get the straw covered. The shape will be sorted out by the second coat (which in some places mat have to go on in several layers to build up low spots) So for now we just smeared our lovely sticky earthen render onto the bales either with our hands or by trowel. We did try spraying the render through a compressed air sprayer, but the straw in the mix Constantly clogged the holes.

We have tried several mixing methods, including using the bucket of an excavator to mix in a hole in the ground (this made an acceptable cob, but didn’t mix nearly thoroughly enough for render) This big Detroit mixer did the job the most successfully.

Far right of this pic is our paint mixing drill which we used for our early trials. Then we bought the Detroit mixer (Pictured centre) and it’s extra large spiral mixing paddle (far left) so here’s our method:

1. 3 buckets of soaked clay soil go into our cast iron bath. (the fibreglass bath was cracked by the mixer head action)

2. Add 1 cup of flour made into a paste with some water.

3. Add 6 buckets of sand and mix to break up the last clumps of softened clay.

4. Add water if need to achieve a thick slurry.

5. Add 3 more buckets of sand and mix, adding more water if needed to have a slightly sloppier consistency than required in the final render.

6. Add 3 buckets of chopped straw and mix, adding more Water only if needed.

Even with the best tools and method we could find, mixing the render is fairly heavy work.