Tuesday, November 27, 2007
Bunch Straw for Making Cob
I did a cob test today, using the adobe dirt from my land. Cob is part sand, part clay, and part straw. There is some clay in the adobe dirt here, but not much. Instead of straw, I used bunch grass ( chino gramma ) , which grows all over the place here. The grass tends to be long and dry this time of year, which is ideal. While grain based straw is recommended for cob, the default rule for natural building is to use what is available. There is a bunch of bunch grass available around here, so that decides that. The cob test worked. It didn’t take long for the test cob ball to dry. I dropped it from about 3 feet onto cement to test its durability. It held together great. Pure adobe would have shattered.