Using Refractory Clay in Cob??....

I am having a lot of trouble getting my hands on local clay in my area, however, I have found a source for Refractory Clay and have heard other talk about using it, but not in any detail. Can I use this to make my cob? If so, what are the ratios I need to use?

Thank you all so much for all the help you've already given me!

Refractory Clay will work just fine, and the ratio will be very similar to that of a good quality found clay. You may find this informative:

http://www.traditionaloven.com/articles/101/what-is-fire-clay-and-where-to-get-it