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Re: GSBN: Japanese plasters



Andy,
When it comes to the sea it was traditionally boiled in water and then the concentrated water/gel added to the plaster. However, it does come now in packages that can be added to the plaster much like boxed wheat paste. Rice was added as a cooked paste but that practice is basically discontinued so it is difficult to say how it was done. It is not added to lime/clay plaster, only the shikkui. Actually I take that back, there are some clay plasters that it is added to as well. It is not applied like a glue to the wall, only mixed into the plaster. As for Confort magazine I don't think you fill find that kind of detail in the text if you were to get it translated. As for fiber, the shikkui contains hemp fiber, but it is the grade used to make clothing. It is not short by any means, but very long and integrating it into the plaster is not an easy task. As for the clay fibers, it is rice straw and I would guess that the only method would be screening it done to different mesh sizes once it has been initially chopped. Without some very fancy processing device that would be the only way to make it happen.

Bill
On Oct 10, 2007, at 3:22 PM, Andy Horn wrote:

Oh another thing Bill,

A couple of years ago I was fortunate to travel to Japan and was hugely impressed by their Shikkui plasters you talk about....even saw a bamboo roof successfully plastered with it. But battled to find anyone to explain the
techniques they use.

Can you explain more about the rice glue or seaweed glue they use/d???

You say they mix it into their plasters....are those with lime clay plasters
or both???

Is it like making a flour paste?

You also seemed to imply they use it to get the lime to stick to their earth walls/plaster layers.... is it put on like a glue just before applying the
lime or is it only added to the lime and or earth plaster layer/s?

Sorry if that is too much to download over an email....and so maybe you know a book where one can learn more about their techniques? I have 2 "Confort"
earth building magazine but still need to find a translator.

One thing I noticed was they used many very thin fine layers of plaster. The other thing I could see was that the plaster seemed to have a very high percentage of the finest of fibres imaginable mixed in with it....which I imagine accounts for its resistance to rain and durability....many of the plasters except the white "shikkui" appeared to be earth plasters without lime, but invariably there was always plenty of very very fine fibre when one examined it closely. Have you any idea how they made such fine fibres and what it was made of ....I was lead to understand it was mostly rice
straw ....but could never understand how they shredded it so fine.

Thanks
Andy


-----Original Message-----
From: GSBN [<a target="_blank" href="mailto:GSBN@...";>mailto:GSBN@...] On Behalf Of Athena &amp; Bill
Steen
Sent: 07 October 2007 04:00 PM
To: GSBN
Subject: Re: GSBN:Re: Lime plaster problems

I'll plead busy as well and before I made any comments I wanted to
make sure they would be somewhat thorough.  There are a few things
that have become evident to me over the years when it comes to lime
over clay plaster.  In mho I would have to say that results are
unpredictable and undependable.  I'm not saying it can't or doesn't
work, but rather that outcomes vary widely. David Bainbridge
mentioned in his earlier post the Getty people in Los Angeles as a
resource.  I've made it a point to talk with them every few years
about lime plaster and in particular their work with prickly pear
cactus gel.  Anyhow in one of the last conversations we had they told
me that there was a growing sentiment amidst the conservation
community that the use of lime plaster over earth surfaces was not
such a good idea.  They mentioned that although lime had better
permeability than cement and allowed the earth to dry better when
wet, it was still too different from an earthen substrate for it to
work dependably.

My experience basically says the same thing.  For me the whole issue
comes down to what type of earth plaster is underneath.  Apparently
some are much better than others and just what all the variables are
I can't say.  I think it will take some time to get a better grasp on
it.  Clearly I would suggest that if the substrate has a lot of clay
there is a likely possibility that if water is absorbed through the
lime plaster and passed on to the earth substrate then obviously the
clay will expand and have a tendency to push the lime plaster away
therefore causing the two to separate.  If the earth plaster is weak
then the connection will break down over time.  So in short I guess
what I'm saying is that the earth plaster has to be of a really good
quality for any chance of success.  It needs to be strong and not
have an overly high content of expansive clay.  Another very
important piece is that the earthen plaster substrate must be
thoroughly dry as earth plasters shrink when drying. If that process
is not complete the earth will pull away from the lime plaster and
leave it hanging in the air. And as others have pointed out the
surface needs to be extremely well keyed for the lime to adhere.  I
don't think you can under-do that aspect.  Additional measures like
that of placing sharp jagged stones in the plaster would also help
such as the practice of "rahuela" used in Mexico where stones are
placed in the mortar joint between adobes.

I think it was David that also mentioned the Japanesete We have
worked closely with a pair of Japanese plasterers over recent years
and it is important to note that the Japanese approach relies heavily
on use of a glue when mixing what they call "Shikkui." Traditionally
rice flour was used but was replaced with seaweed gel during a time
of food shortages.  In general I would say that their plastering
practices are far more meticulous than anything I've seen in this
part of the world and in the words of the best plasterer from there
that I can think of, "there is great difficulty in the connection
between the two coats and at best it does not last for a very long
time."

Having said all this I will say that my comments apply primarily to
exterior finishes and I've not yet experienced any problems with
interior or protected locations.  But I should add that we also
typically include a percentage of some glue material in the lime
plaster.

John Glassford suggested the use of lime/clay as an alternative and I
think that it can be a very good one.  Much here depends upon the
reaction between the clay soil and the lime. Over the years I've
watched varying reactions, some soils produce exceptional results,
others marginal.  I recently cornered Harry Francis who once worked
for the American Lime Association while we happened to be together
recently in Washington DC.  I told him that the using pH as an
indicator of the right type of mix was not proving true all of the
time.  Like he always does Harry went home and searched his extensive
resources and just emailed me a paper that addresses some of those
variables particularly soils with high levels of potassium and sodium
carbonates.  I haven't had time to really absorb the content, but if
any of you want a copy I would be happy to forward it.

I've already said more than I had intended, but to sum it up I would
not suggest that we recommend the use of lime plaster over earthen
substrates as a general practice.  I would suggest that it be adopted
only after some testing and experimentation has been done and with a
warning that the results are always guaranteed.

Bill
On Oct 7, 2007, at 7:10 AM, Rikki Nitzkin wrote:

Sorry to chime in so late...been busy. Its just that I haven't seen
anywhere
that in the responses to remind Andy that it is very important to
wet down
as well as scratch the base layer of plaster before applying a new
coat, and
if the material is different (lime on clay in this case) really rub
the
first bit in so it binds well.

Hope your problem has been solved.

Rikki Nitzkin
Aul?s, Lleida, Espa?a
rikkinitzkin@...
(0034)657 33 51 62
www.casasdepaja.com (Red de Construcci?n con Balas de Paja)


-----Mensaje original-----
De: GSBN [<a  target="_blank" href="mailto:GSBN@...";>mailto:GSBN@...] En nombre de Brian
Hodge -
Anvill
Enviado el: jueves, 27 de septiembre de 2007 22:20
Para: 'GSBN'
Asunto: RE: GSBN:Re: Lime plaster problems

Hi Andy,
I agree with John. We have been doing a very similar thing for
about 5
years and have not found it necessary to add the lime putty top
coat. We
have even done it without chaff with a great deal of success.

Regards

Brian

Anvil Straw

-----Original Message-----
From: GSBN [<a  target="_blank" href="mailto:GSBN@...";>mailto:GSBN@...] On Behalf Of John
Glassford
Sent: Thursday, 27 September 2007 7:53 AM
To: GSBN
Cc: Andy Horn
Subject: Re: GSBN:Re: Lime plaster problems


G ' day Andy

My two rands worth mate.

You will need to remove the lime coat and scratch up the earth as
others
have said.

I would then apply a mix of earth/lime/sand and chaff or chopped
straw.

All depends on the clay content of your earth but I would look at
something like this 3 parts soil 2 parts lime 3 parts sand 1 part
chaff.
I use buckets for this mix.  It works well and binds well with the
earthen render. Then if you want you can apply a finish coat of lime
render however I have not found that necessary in most cases
except for
look.

You can see a house we renedered with earth, then earth/lime/sand/
chaff,
then lime/sand, here:

<a  target="_blank" href="http://glassford.com.au/Jumbo.htm";>http://glassford.com.au/Jumbo.htm</a>

No delamination no cracks and it is nearly 6 years since we finished
there.

Was in Cape Town a few weeks ago but did not have time to see much it
was a Rotary trip with Hout Bay.  We will be back next year for an
extended visit, see you then.

Kind regards
The Straw Wolf
Huff 'n' Puff Constructions
<a  target="_blank" href="http://www.glassford.com.au/";>http://www.glassford.com.au/</a>

61 2 6927 6027

Mount Kilimanjaro Climb 28/8/07 <a  target="_blank" href="http://www.coolamonrotary.com/kili/";>http://www.coolamonrotary.com/kili/</a>
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Athena &amp; Bill Steen
The Canelo Project
HC1 Box 324
Canelo/Elgin, AZ 85611
absteen@...
www.caneloproject.com


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For instructions on joining, leaving, or otherwise using the GSBN list, send email to GSBN@...HELP in the SUBJECT line.
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Athena &amp; Bill Steen
The Canelo Project
HC1 Box 324
Canelo/Elgin, AZ 85611
absteen@...
www.caneloproject.com