Cob Do I really need sand in my clay?

[Adam Aaron Weiss]

In answer to your question about the cracks, I think it has more to do
with the rate of drying than the ration of materials.  That is to say if
you let the clay dry too quickly the wall will crack.  In Germany where I
worked building houses out of a straw and clay mixture, and plastering
them with a sand/clay plaster we wet the walls down with a brush and a
slip coat to stop the cracking.  Good Luck.

Adam Weiss

On Mon, 28 Jul 1997, FROG wrote:

> 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
> 
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>  Sam Droege  FROG at NBS.GOV                      
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> 
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