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Re: GSBN:Earth plasters



Hello Andy;
I have built several ecological buildings in Morocco a couple of tears ago.
We used plenty of Taddelakt  to waterproof  baths and hammams (sweat bath).
It is a very ancient tradition and when well done, a perfect waterproofing.,
and a great decoration too (looks like polished marmor, but slightly
smoother, and less cold to the eye and the skin.).
The basis is lime, rough lime as they use to have in morocco Must absolutely
be air lime, not hydraulic. Hardens slowly, as carbon in the air
re-carbonates it.
You add some pigments (natural earth oxides are the best) and mix it with
water to a porridge constency.  allow a night rest.
The wall has to be fairly hard, and rough enough so the mix sticks to it
when pressed on it. Rough cement is good, or an undercoat of lime and gross
sand, dry since a week or two. Humidificate before starting the job.  It
needs a bit of training though.
. The mix has to be uniformely spread on the wall, in a thickness of min. 5
milimeters, and a max of 10, typically. Then the jobs starts really, as you
must press it gently but firmly (there lies the tricky side) to erase all
primary tracks, and make a more compact  coat.Have in mind the will be only
one coat,  so better training on odd pieces of walls, bricks etc before
doing the wall you want to look good.
If you can have someone who did it before, let him show you,  it 'll save
time and efforts.
In a way, the finishings is similar to fine earth plaster, as it requires
hand polishing with a smooth, flat stone. Instead of oil, moroccans use
black soap. a thick "honey like" soap, maid with olive oil and plants. then
the plaster  is left to dry for a week,  and  will harden more and more as
time passes.
Cheers
Lorenzo
----- Original Message -----
From: "Andy Horn" andy@...
To: "'GSBN'" GSBN@...
Sent: Wednesday, October 17, 2007 12:07 PM
Subject: GSBN:Earth plasters


Does anyone know about the Moroccan takalak plasters, which are apparently
used in bathrooms? I believe they are supposedly used in waterproofing of
baths and showers too?
Andy

-----Original Message-----
From: GSBN [<a  target="_blank" href="mailto:GSBN@...";>mailto:GSBN@...] On Behalf Of Graeme North
Sent: 11 October 2007 09:32 PM
To: GSBN
Subject: Re: GSBN: Earth plasters

Hi Mark &#xD0; I&#xD5;ve not found mould on earth plasters to be a problem &#xD0; I have
seen
darker surface &#xD2;patches&#xD3; on fermented earthen material eg mud bricks or
cob
where the  mix had sat for a while (weeks) before using and had fermented
a
bit, but I do not think these darker patches that arise from this are
mould.
Mould may occur if the walls are very slow to dry and/or are not fully dry
beneath earth plasters, or else the building does not have sufficient
eaves
and moisture keeps the wall wet.
I&#xD5;ve got earthen plasters (with paper pulp) in my own bathroom where they
get
really steamy at times, (from showering) which not only dry out really
quickly, but also suck moisture out of towels and wet floors keeping the
room
really dry &#xD0; there is no mould after three or more years of this, even
though
we live in a wet and humid climate &#xD0; virtually never less than 60%, often
well
over 80% - 90%.

cheers

Graeme






Graeme,

Thanks for your submission and insight. The first I'd heard of
'fermenting'
straw (or paper) was from some friends from NZ, Sven and Sarah Johnston,
who hosted a workshop and a guest presenter was Tom Raven, the colorful
Frenchman, who uses a fermented mix, like bakers use a yeast starter for
baking breads. Tom swears by this fermenting and concurs with you on added
durability of the earth plasters. The Johnstons found they had some mold
issues, maybe as a result of this mix tho. Have you experience any issues
with molds?




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