Cob Clay, Fibers, & FC

[Keftydia at aol.com]

Greetings All,

First off, I'd like to say how great it is to find you guys online.  I've been
interested in cob for some time and finding a discussion group of fellow mud
puppies was a thrill!

So, for my first question/contribution to the list, I have a concern about
clay.  In this area, we have two types of clay:  an orangey-reddish clay that
is most often found in the upper levels of soil, and a sticky grey clay (it's
called gumbo around here) that is often found a bit deeper.  While I suspect
clay is clay, instinct tells me that the gumbo would be a better choice to use
for cob.  From the broad range of experience out there, I'm wondering if you
all feel there is any benefit to using one or the other?

Second, I'm curious about what plant fibers work well in cob.  I've read the
archives (yes, ALL of them!) and while I've read of folks using plant material
other than straw, I'm curious if anyone has tried pine straw?  With all the
pines in South Carolina, we have an abundance of the stuff.

Finally, regarding fibrous cement: if I understand correctly, one of the main
drawbacks to the material is water absorbency, making it unsuitable for
exterior walls and such in wetter climates.  However, what about using it for
lightweight, non-structural interior walls?

Metta to all,

Ron Cameron