Cob Do I really need sand in my clay?

[FROG]

Hi Folks:

I have done some experimenting with cob/earth plaster mixes and it seems to me 
that there is very little correspondence in how many cracks develop and the 
ratio of sand to clay.  Does anyone have any reason why I can't therefore just 
dispense with the sand?

Thanks

sam

                                               
   0<    0-      0<    0-      0<    0-      0<
->>)   ->>)   ->>)   ->>)   ->>)   ->>)   ->>) 
  L      L      L      L      L      L      L  
                                               
 Sam Droege  FROG at NBS.GOV                      
 w 301-497-5840 h 410-798-6759 fax 301-497-5784
PWRC, 12100 Beech Forest Dr., Laurel, Md 20708-4038
Http://www.im.nbs.gov

          But nature is a stranger yet; 
          The ones that cite her most 
          Have never passed her haunted house, 
          Nor simplified her ghost. 

          To pity those that know her not 
          Is helped by the regret 
          That those who know her, know her less 
          The nearer her they get. 
                --Emily Dickinson