Cob cob / ceramics

[Carol M.]

Lars Fields wrote:

>  > lars wrote:
>  >        this is kind of an aside - maybe pat newberry might know best:  does
> > anybody know why it is inappropriate to mix straw with clay if one is making
>  > bricks for a fired structure 'a la nader khalili'?

Hi Lars,

I don't know all that much about cob but I do know something about firing ceramics -
have had my own kiln for over 10 years and do a lot of things hand built with clay
that I later fire.

Any air bubble at all left in clay that's being fired will cause it to explode - in a
big way.  So if you got the cob hot enough to bake hard, most likely at least some of
the straw would vaporize and the expanding gases would cause explosions also.  I sure
wouldn't want to be anywhere around when you were firing a cob structure.<g>  One of
the most important steps in working with clay is to be sure all contaminates (leaves,
twigs, sticks, etc.) are out of it before you start building a pot.  So I'd think
that firing cob would be a rather hair-raising experience.  And one where a lot of
people could be badly hurt.

Mind you, I'm not at all experienced with cob, but you sure do need to check with
some other people before trying to fire it.  If you know a potter in your area, who
does hand building with clay, that might be a good place to start for basic info.

Carol