In the afternoon Barbara, Michela and I started to cob the fire heated tub. We made the cob like we did yesterday, by forming a well in the sifted dirt and filling it with water.
This method is similar to the way you would make pasta, but obviously on a much larger scale. Cob can be made a variety of different ways and everyone has their own style. The pasta way is the way that Jill showed us yesterday. Barbara usually layers the dirt and straw sprinkling water between the layers. You can also add dirt at the end if it is too wet and you have added enough straw. There are no rules to how you do it, which is one of the reasons it is such a wonderful material. Every person does it differently. Barbara recommends sprinkling a layer of straw on the tarp before you pile the dirt so that the cob doesn’t stick too much to the tarp. Here are photos of the work we did today…
After we mixed the cob with our feet we kneaded it into balls. This process further incorporates the straw with the mud and gets out any air pockets that may be trapped inside.
You should wet the surface you are cobbing so that it does not suck moisture out of the cob and it helps the cob adhere to the other surface, regardless of it being concrete or cob.
We use a string to get an idea of what slope we needed to form with the cob. The rocks around the bottom will act as a shelf for the cob to sit on.
Its good to smack the cob on to the concrete to create a good bond and ensure the cob gets in all the nooks and crannies. Cob is applied in horizontal layers.
Using fingers or a stick to create indents in the cob weaves the fibers together and strengthens the bond between the layers. Indents should be made in a downward direction into the cob. The next layer of cob can be pushed into downward indents far better than it can be pushed into upward indents.
Tomorrow we will be holding a cob workshop here at Bean Tree so I will post photos of that. Bellow are video I encountered and thought I should share…