[Cob] Curious about the clay

[Damon Howell]

Isn't there a simple test for the presence of enough clay...

Yes, there are simple tests you can do. You CAN have plenty of clay  
and be deceived by unsticky soil by simply not wetting it enough  
before the test. And you can also have a disaster if you wet it too  
much. The fastest way to spot clay is wet it down grab some in your  
hand and make a fist. If it ribbons out through the cracks in your  
hand you have good clay. If it stays inside your fist it probably has  
no clay. Take note: not much clay is needed for cob. The best way is  
make a brick, let it dry and see how hard it is to destroy. The  
harder the better.

Damon in GA