Cob: organic materials for earthen plaster ???

[Darel Henman]

"dello.mo at libero.it" wrote:
> 
> Hello
> 
> I am an architect, I want to apply earthen plaster on a wall for
> reasons of study. I want to use the white of egg, the blood, ash of
> olive ,emulsion of figs ,…...
> As it mentioned in the ancient traditions….

It's hard to help unless you give us the proportions of the mixtures for
each ingredient.

> 1)Can be used organic materials in earthen plasters...
>     which are the negative effects?

I've heard that in general it weakens the mix.  They will decay in
several years.  But, I'm sure this would depend on the exact substance. 
For example for seaweed glue, it is mainly used only to aid in
workability of a lime mortar, but it doesn't last as long as a simple
water mixed mortar.  It's just easier to apply. I am talking about a
plaster mortar.  Egg whites have also been used as was mentioned earlier
for a paint base.

I think that would be the use of egg whites.  It would enable the mix to
hold water for longer which would give the plasterer more time to apply
it.  If a mix looses water too fast a good even application may not be
possible or at least as easy.  Egg whites are soluble in water, unless
they reach 60 deg_C or 140 deg_F.

> 2) how can we protect them from these effects ?
Keep it from getting ultra-violet sun rays and heavy rain, might help.

> 3) there is an earthen mortar in Ancient Anatolia called
>     “Horasan” composed of: earth, lime, powder of bricks, and
>      sometimes mixed with the  white of egg.

The powder from burned bricks is a pozzolan, and will make the resulting
mix into a harder more durable material when dry.  There is information
about this somewhere in cyberland, but not much.

>  I hope to hear something new about the prescription of that mortar.
What proportions where your given?

Darel