Wednesday, October 6, 1999 6:10:58 PM
GSBN Item
From: GSBN@...,Txinfinet Incoming
Subject: Digest for 10/6/99
To: GSBN
-> fwd from Martin Oehlmann
by (email address removed)(Bill Christensen)

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Date: 6 Oct 1999 11:44:06 -0500
From: (email address removed)(Bill Christensen)
Subject: fwd from Martin Oehlmann


Hi all!

Back from Brittany again having had great fun to build together with Pascal
Thepaut the walls for a round, beautiful post and beam structure I would like
to
respond on the clay - lime discussion:

At the butterfly house in Ouwerkerk, The Netherlands, we left the idea of
using the reported enzyme protection as we discovered some chemicals mixed in
which can invoke cancer. However these chemicals will not remain in the wall
but
disappair in the air after treatment.

Surprisingly the whey(casein)/limewash performs now extraordinary well on the
clay walls
exposed to rough weather. To the lime - delivered in sacks - whey
has been added instead of water. An expert on clay protection sayd, this
method

is the best he knows, better than the product his company (KEIM) is
offering.

We tested an area spraying 1 hour water with a tube on the wall. 0% increase
of humidity measered over a period of days. Caused by the pressure of the
water

some miniscule particles of the wey/limewash protection had been removed. So
end
of October we will brush in a second layer on the weather side to really make
sure no water will penetrate the walls.

Conclusion: Due to a not properly dryed underlaying claystucco and to rain
exposure cq high humidity, the wey/limewash could not perform its protection
last winter. The drying period of clay stucco takes some month if outside
humidity remains too high. In Ouwerkerk it took about 9 month in general, much
to long for general use which indicated a 40% moisture peak and the following
removal of 3 rotten bales. The clay / straw mixture (light clay) being used to
fill gaps between the top layer of the bales and the roof are still not dry
yet, yet the underlaying bales are dry.

It seems to be too riscy to apply a clay stucco at strawbale houses in or
beforerainy periods. Alternatively limestucco dries much quicker than clay and
performs very well during the last 12 years in Brittany. At the house in
Lannion Pascal uses the proved 3 layers when the weather will be dry
again. The last weekend he did offer a workshop on lime-stuccoing for adepts.

What will be interesting in these wet climates is to find an additive that
shortens the drying period of clay, as clay feels to be the most wonderful
natural stucco for straw-bale buildings. Again lime is used to produce cold
pressed (not baked) adobe bricks at a small factury in Brittany, maybe an
avenue
to follow.

In December I will have the opportunity to held a lecture at the university
of Kassel at the faculty of prof. Minke, the clay specialist in Germany.
Hopefully this visit will add some more insights.

Best wishes,
Martin
martin.oehlmann@...

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