Cob: white clay

[Brad Calvert]

Nearby I saw some excavation work and noticed lumps of white clay among the
usual brown clay.  Maybe white clay occurs in seams that could be dug out
with a spade, but this was relatively mixed up.  There were quite a few
brick-sized lumps of pure white clay, slightly creamy in colour.

I made two experimental mud pies, tennis ball sized, with white/light sand
from the beach, the end result looked very much like sandstone, which I
guess is not surprising.  A cob structure made from this might look like it
was carved from a single piece of sandstone.

One pie was one part clay to two parts sand, the other 1:4.

I would say the 1:4 pie had barely enough clay to hold it together and took
a lot more mixing to make sure the clay was smeared and broken up
effectively.  I just used my fingers on a piece of flat stone.

I was thinking about cement mixers, maybe they would be Ok to mix dry(ish)
ingredients, to avoid it all sticking to the sides, but wet enough so clay
dust does not go everywhere.