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Re: GSBN: Earth plasters
- To: "GSBN" GSBN@...
- Subject: Re: GSBN: Earth plasters
- From: Athena & Bill Steen absteen@...
- Date: Fri, 12 Oct 2007 08:19:10 -0700
- Reply-to: "GSBN" GSBN@...
- Sender: "GSBN" GSBN@...
Couple of things. First of all (laughing), plastering in NZ I think
is a tad bit different than dehydrated parts of the world such as
where I live. I suspect Andy's part of the world is in the dehydrated
But on to what you said about fermenting plaster. I have found that
the longer any earth plaster ages the better it seems to get.
Especially this applies to those containing some fiber whether it be
straw or paper. Even for short periods of time we've had large
batches of clay and straw plaster rise like bread dough, quite
amazing. The only objectionable thing about longer periods is that
there is a definite organic odor that comes with it. Personally it
doesn't bother me, but others don't get overly excited about it. To
see if I can help those who are sensitive we've started some
experimental batches with EM, a product known as Essential
Microorganisms to see if it alters the process somewhat.
Anyhow, what I like about the fermented mixes is that the character
of the mix changes entirely. It is hard to describe, but it becomes
much more pliable, plastic, easy to work and the breakdown of fiber I
suspect makes it less susceptible to mold when drying in wetter
The only down side about adding too much paper for an interior
plaster is that you're going to sacrifice thermal mass and since that
is an impt ingredient when it comes to the performance of a SB
building it would seem we don't want to sacrifice that.
On Oct 10, 2007, at 2:05 PM, Graeme North wrote:
We have found the addition of pulped paper as a fine fibre very
Its made either from office paper or newspaper it can be made by
soaked paper into a concrete mixer with lots of water and just
roll until completely broken up , then draining off excess water
It gives a very fine fibre which is enormously beneficial in terms of
increasing strength, and durability of earth plasters. If it
ferments a bit
even better (all ferment seems to help earth plasters using water
had a bit of straw left in it for a week or two to start to fizz is
well) Ð there appears to be some enzymic reaction that takes place
paper or ferment water and clay that helps workability and durability.
Paper pulp eliminates dusting from earth plasters helpful
the soil is a bit silty. It also sticks well we use it over
pre-compressed straw without meshing.
We also use it as a finishing plaster over drywall a very nice
it sticks like ...glue.
It is also very effective as an additive to earth bricks as well
robustness, durability, and also lowers density giving better
The amount of paper pulp that can be added can be quite high - we
up to around 30% or so by volume to plaster , and have made mud
up to 50% paper pulp cardboard houses anyone?
I am currently looking at building with cob and mud brick mixes using
roughly 2 parts clay-soil, 2 parts wood shavings (long fibered
straw, and 1 part paper pulp very tough, very light, easy to work,
looking promising. Very good insulation, and very nice to use as
increases remember that there is plenty of evidence that gravity
in strength very thirty years.
As to lime over earth IÕve found it works well so far IF there is
keying and wetting if the initial earth is a cob type mix with
(straw) fibre with plenty of fibres left hanging out of a rough
then that is good too for tying the layers together.
IÕve just lost a patch off a bit of a small experimental earth
whitewashed straw wall where the earth plasters layers were not
together. Keying is good.
Graeme North Architects,
49 Matthew Road,
New Zealand 0981
Ph/fax +64 (0)9 4259305
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Athena & Bill Steen
The Canelo Project
HC1 Box 324
Canelo/Elgin, AZ 85611