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GSBN: Digest for 10/10/07



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---------------------------------------------------------------------


-> Re: GSBN:Re: Lime plaster problems
     by Bergeron m.bergeron@...
-> Re: Marks post about biophilic buildings
     by MattsMyhrman@...
-> Re: GSBN:Re: Lime plaster problems
     by MattsMyhrman@...
-> Re: GSBN:Re: Buffalo Grass Bales and Sudan Grass Bales
     by MattsMyhrman@...
-> Re: GSBN:Re: Buffalo Grass Bales and Sudan Grass Bales
     by Ben bobregon@...
-> RE: GSBN:Re: Lime plaster problems
     by "Andy Horn" andy@...
-> GSBN: Japanese plasters
     by "Andy Horn" andy@...
-> GSBN: Lime plaster problems
     by "Andy Horn" andy@...
-> Re: GSBN: Earth plasters
     by Graeme North ecodesign@...
-> Re: GSBN: Lime plaster problems
     by thangmaker@...


----------------------------------------------------------------------

Date: 10 Oct 2007 08:37:08 -0500
From: Bergeron m.bergeron@...
Subject: Re: GSBN:Re: Lime plaster problems

Hello Bill,

I am very interested by mr Francis paper. If you mind forwarding it to me, I
would appreciate.

Best regards to you and Athena,

Michel Bergeron
Designer
6282, de Saint-Vallier
Montreal. Que.
H2S 2P5
(514) 271-8684
m.bergeron@...


Le 07/10/07 12:00, << Athena &amp; Bill Steen >> absteen@... a ecrit :

> 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
>> Aulas, Lleida, Espana
>> rikkinitzkin@...
>> (0034)657 33 51 62
>> www.casasdepaja.com (Red de Construccion 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>
>>> ----
>>> For instructions on joining, leaving, or otherwise using the GSBN
>>> list,
>>> send email to GSBN@...HELP in the SUBJECT
>>> line.
>>> 
>>> ----
>>> 
>>> 
>>> 
>>> 
>>> ----
>>> For instructions on joining, leaving, or otherwise using the GSBN
>>> list,
>>> send email to GSBN@...HELP in the SUBJECT
>>> line.
>>> ----
>> 
>> ----
>> For instructions on joining, leaving, or otherwise using the GSBN
>> list, send email to GSBN@...HELP in the
>> SUBJECT line.
>> ----
>> 
> 
> Athena &amp; Bill Steen
> The Canelo Project
> HC1 Box 324
> Canelo/Elgin, AZ 85611
> absteen@...
> www.caneloproject.com
> 
> 
> ----
> For instructions on joining, leaving, or otherwise using the GSBN list, send
> email to GSBN@...HELP in the SUBJECT line.
> ----
> 




----------------------------------------------------------------------

Date: 10 Oct 2007 09:23:26 -0500
From: MattsMyhrman@...
Subject: Re: Marks post about biophilic buildings

In a message dated 10/7/2007 12:53:19 PM US Mountain Standard Time,
mark@...:

>
> Mark has shared the following
> member-only page from BuildingGreen Suite. If you find this page
> valuable, we encourage you to
>
>

I thank Mark for this fascinating post.  It's this kind of thing that makes
checking every post to the GSBN worthwhile.



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Date: 10 Oct 2007 10:31:29 -0500
From: MattsMyhrman@...
Subject: Re: GSBN:Re: Lime plaster problems

In a message dated 10/7/2007 3:10:08 PM US Mountain Standard Time,
thangmaker@...:

> This is the clay I wanted to use for the fire test last year in San Antonio
> but as Matts pointed out it would not well in a hot fire.

Rather than "it WOULD not perform well", I certainly meant to say "it MIGHT
WELL not perform well".  My concern was/is based on the likelihood that the
heat could rapidly convert any larger particles of calcium carbonate (a
mineral
that is called limestone when it occurs as a layer of rock) to calcium oxide,
with the production of carbon dioxide gas.  I was concerned that, especially
for any larger particles near the surface of the plaster, this process might
cause a spalling off of the clay between the particle and the surface.  This
might weaken the plaster.  Since the stakes were very high in these expensive
tests, I thought it unwise to take any chances that could be avoided.  The
clay-rich soil that Frank provided as an alternative to the caliche-clay 
performed
quite well, in my estimation.


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Date: 10 Oct 2007 14:36:22 -0500
From: MattsMyhrman@...
Subject: Re: GSBN:Re: Buffalo Grass Bales and Sudan Grass Bales

Looks like Ben got some thoughtful posts, but we might have been able to
craft better ones if he could have provided the scientific name for what they
call
Buffalo Grass down in Tejas.  Or, at least, have provided a detailed
description of the stuff.
So much for constructive (?) grumpiness.

That said, the second Out On Bale workshop,circa 1990, put the walls up of a
drum-making studio for Steve Kemble.  The bales were Sudan Grass.  As I
recall, the stems were quite coarse, but the bales seemed fine.  I have also
seen a
privacy wall made with bales of pinto bean stalks, and buildings made with
baled cardboard.  It would, indeed, seem that if you can make a tight bale of
reasonable weight, it should work.  Think rice straw bales, eh?



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Date: 10 Oct 2007 15:13:22 -0500
From: Ben bobregon@...
Subject: Re: GSBN:Re: Buffalo Grass Bales and Sudan Grass Bales

Thanks Matts, I stand humbled. I do appreciate the info from you all and
should have provided a better description of the characteristics of
'Buffalo Grass'. I've included some additional info below but I think
the most important thing I got from everyone is that I should look at
the specific characteristics of the grass on their land to insure the
stalk's characteristics are close enough to straw..

Thank You all

Ben Obregon



    Bouteloua dactyloides (Nutt.) J.T. Columbus


      Buffalo Grass, Buffalograss


      Poaceae (Grass Family)
     
<<a  target="_blank" href="http://www.wildflower.org/plants/search.php?family=Poaceae&amp;newsearch=true";>http://www.wildflower.org/plants/search.php?family=Poaceae&amp;newsearch=true</a>>


      Synonyms: Buchloe dactyloides


      USDA Symbol: BODA2 <<a  target="_blank" href="http://plants.usda.gov/java/profile?symbol=BODA2";>http://plants.usda.gov/java/profile?symbol=BODA2</a>>


      USDA Native Status: Native to U.S.


<a  target="_blank" href="http://www.wildflower.org/plants/";>http://www.wildflower.org/plants/</a>

>Looks like Ben got some thoughtful posts, but we might have been able to
>craft better ones if he could have provided the scientific name for what they
call
>Buffalo Grass down in Tejas.  Or, at least, have provided a detailed
>description of the stuff.
>So much for constructive (?) grumpiness.
>
>----
>
>
>
>


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Date: 10 Oct 2007 15:14:44 -0500
From: "Andy Horn" andy@...
Subject: RE: GSBN:Re: Lime plaster problems

Dear Bill and others
Much appreciate your well considered most informative response.
Please do forward me the paper you were talking about thanks.

I have done some investigation into the mineral content of the soil talking
to a knowledgeable engineer / farmer who said that the red  soils we used,
which are common to the area are generally quite acidic  .... He also
explained that there used to be pine plantations in that specific area and
guessed the PH would be about 4,5 to 5. He also suggested that we could
check the PH of the water we used...if you think that will also influence
the results. He said with farming that meant they usually have to add quite
a lot of extra agricultural lime to the soil to help balance the PH. If what
you are saying is that with acidic soils/water we should use a stronger lime
mix ...then I guess our mix did not have enough lime in it. We used 25% lime
mix and probably should have used a 33% lime mix???? The mix was 2 parts
soil, 7 parts sand and 3 parts lime. (The receipt I used was to substitute 1
part of the 3 parts of sand with the adobe mix)

Our adobe mix was 2 parts soil and 1 parts sand and made excellent bricks
which were very well cured and the whole wall had had months of curing
before any plastering. 

Apparently the soils (from Dolerite bedrock) apparently have a very high
aluminum content...not sure if that would have played a part in it???

Not sure about the sodium carbonate levels but the potassium and phosphate
levels are very low (2-3 parts per million).

The soils also have a fairly low P.I. and we did not experience much
shrinkage. However we did wet the walls down very well before applying the
plaster and may have even over done the wetting of the walls afterwards as I
wanted to ensure the lime cured well......however this was negated in the
most part by the unusually occurring and excessive winds, which occurred
during the middle of the days over the period I was there. With the pressure
to get the job all done while I was up there, we pressed on, instead of
postponing the whole thing as in retrospect is what I should have done.

Furthermore in retrospect the keying was certainly not sufficient.

Historically in the Cape, which I am more familiar with, most of our old
earth buildings (of which there are many 100 - 300 years old) were always
protected with a good coat of lime plaster. Sometimes however lime plaster
was not used and rather a cow dung earth plaster was used followed by
regular coats of lime wash...though at the coast where we experience strong
wind driven rains a lime coating was the norm. No doubt our forefathers knew
a thing or two about lime that helped them get it right.....so I have always
had the greatest of confidence in lime plaster....up until now!

Kind thanks
Andy

ECO DESIGN
Architects &amp; Consultants
A. R. HORN B.A.S. (UCT), B.Arch (UCT), Pr.Arch (SACAP),       MIA, CIA
Telephone: 021 462 1614, Fax: 021 461 3198
Cel: 082 67 62110
4th Flr, The Armoury
160 Sir Lowry Rd
CAPE TOWN
7925
web site:  HYPERLINK www.ecodesignarchitects.co.za
www.ecodesignarchitects.co.za
email: 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
> Aulas, Lleida, Espana
> rikkinitzkin@...
> (0034)657 33 51 62
> www.casasdepaja.com (Red de Construccion 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>
>> ----
>> For instructions on joining, leaving, or otherwise using the GSBN  
>> list,
>> send email to GSBN@...HELP in the SUBJECT  
>> line.
>>
>> ----
>>
>>
>>
>>
>> ----
>> For instructions on joining, leaving, or otherwise using the GSBN  
>> list,
>> send email to GSBN@...HELP in the SUBJECT  
>> line.
>> ----
>
> ----
> For instructions on joining, leaving, or otherwise using the GSBN  
> list, send email to GSBN@...HELP in the  
> SUBJECT line.
> ----
>

Athena &amp; Bill Steen
The Canelo Project
HC1 Box 324
Canelo/Elgin, AZ 85611
absteen@...
www.caneloproject.com


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Date: 10 Oct 2007 15:32:27 -0500
From: "Andy Horn" andy@...
Subject: GSBN: Japanese plasters

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
> Aulas, Lleida, Espana
> rikkinitzkin@...
> (0034)657 33 51 62
> www.casasdepaja.com (Red de Construccion 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>
>> ----
>> For instructions on joining, leaving, or otherwise using the GSBN  
>> list,
>> send email to GSBN@...HELP in the SUBJECT  
>> line.
>>
>> ----
>>
>>
>>
>>
>> ----
>> For instructions on joining, leaving, or otherwise using the GSBN  
>> list,
>> send email to GSBN@...HELP in the SUBJECT  
>> line.
>> ----
>
> ----
> For instructions on joining, leaving, or otherwise using the GSBN  
> list, send email to GSBN@...HELP in the  
> SUBJECT line.
> ----
>

Athena &amp; Bill Steen
The Canelo Project
HC1 Box 324
Canelo/Elgin, AZ 85611
absteen@...
www.caneloproject.com


- ----
For instructions on joining, leaving, or otherwise using the GSBN list, send
email to GSBN@...HELP in the SUBJECT line.  
- ----


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Version: 7.5.488 / Virus Database: 269.14.1/1050 - Release Date: 2007/10/04
05:03 PM
 

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Checked by AVG Free Edition. 
Version: 7.5.488 / Virus Database: 269.14.1/1050 - Release Date: 2007/10/04
05:03 PM
 



----------------------------------------------------------------------

Date: 10 Oct 2007 15:45:26 -0500
From: "Andy Horn" andy@...
Subject: GSBN: Lime plaster problems

Interestingly the locals in Kokstad who build with adobe ...but don't add
sand to help with cracking will search to find a much rarer creamy coloured
clay that can be found in the area to do their plaster coat with....and will
then typically apply a lime wash to finish with. However they have not
learnt to add sand so the walls are usually quite crazed with
cracks.....Sometimes they also add cow dung which helps somewhat with the
cracking.

Not sure if we can get any marble dust in that area,,,,but as I understand
it you would want that in the earth plaster to get the bond to the lime
coat......

Interestingly I hear from an archaeologist/conservator friend of mine that
the Romans often used to add marble dust to their lime plaster. The other
thing the Romans did was add fine fired brick or tile dust/powder to their
mixes.....not sure what that was for or if it was simply instead of or when
they ran short of sand???
 
Andy Horn

- -----Original Message-----
From: GSBN [<a  target="_blank" href="mailto:GSBN@...";>mailto:GSBN@...] On Behalf Of Athena &amp; Bill
Steen
Sent: 08 October 2007 02:02 PM
To: GSBN
Subject: Re: GSBN:Re: Lime plaster problems

Franko,
I think a major plus in your area is the calcium component in the  
caliche soils.  So therefore we have a chemical connection going on  
beside the mechanical.  And that is what is basically lacking with  
most soils.  One way to increase the possibility of a better chemical  
bond is to use marble aggregate instead of quartz sand.

B...
On Oct 7, 2007, at 2:50 PM, thangmaker@...:

> Thank you, Bill.  I have had good results and no problems to date  
> putting lime over earthen plaster made with our native caliche  
> clay.  We have done what Bill
>
>
> suggests:  scratching the surface well and letting the earthen  
> plaster dry completely.  For those unfamiliar with caliche it  
> occurs in the same soil as limestone.
>
>
> It is the same basic material as lime (calcium carbonate) but less  
> dense and not well bonded to itself...flakey if you will.    
> Occasionally clay is found with this
>
>
> material and is the best clay I have seen in terms of PI index (low  
> expansion and contraction).   This is the clay I wanted to use for  
> the fire test last year in San Antonio but as Matts pointed out it  
> would not perform well in a hot fire.   I am guessing the material  
> is similar enough to lime plaster that it both bonds well to it and  
> their rate of movment and reaction to moisture is similar.
>
>
>
>
>
> Cheers
>
>
> Frank Meyer
>
>
> PS we are hosting a Natural Building Colloquim later this month  
> www.naturalbuildingtexas.org and have a great caliche clay pit on  
> site.
>
>
> -----Original Message-----
>
> From: Athena &amp; Bill Steen
>
> To: GSBN
>
> Sent: Sun, Oct 7 12:11 PM
>
> 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
>
>> Aulas, Lleida, Espana
>
>> rikkinitzkin@...
>
>> (0034)657 33 51 62
>
>> www.casasdepaja.com (Red de Construccion 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>
>
>>> ----
>
>>> For instructions on joining, leaving, or otherwise using the GSBN  
>>> >> list,
>
>>> send email to GSBN@...HELP in the  
>>> SUBJECT >> line.
>
>>>
>
>>> ----
>
>>>
>
>>>
>
>>>
>
>>>
>
>>> ----
>
>>> For instructions on joining, leaving, or otherwise using the GSBN  
>>> >> list,
>
>>> send email to GSBN@...HELP in the  
>>> SUBJECT >> line.
>
>>> ----
>
>>
>
>> ----
>
>> For instructions on joining, leaving, or otherwise using the GSBN  
>> > list, send email to GSBN@...HELP in the  
>> > SUBJECT line.
>
>> ----
>
>>
>
>
>
> Athena &amp; Bill Steen
>
> The Canelo Project
>
> HC1 Box 324
>
> Canelo/Elgin, AZ 85611
>
> absteen@...
>
> www.caneloproject.com
>
>
>
> ----
>
> For instructions on joining, leaving, or otherwise using the GSBN  
> list, send email to GSBN@...HELP in the  
> SUBJECT line. ----
>
>
> ______________________________________________________________________ 
> __
> Email and AIM finally together. You've gotta check out free AOL  
> Mail! - <a  target="_blank" href="http://mail.aol.com";>http://mail.aol.com</a>
>
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> ----
>

Athena &amp; Bill Steen
The Canelo Project
HC1 Box 324
Canelo/Elgin, AZ 85611
absteen@...
www.caneloproject.com


- ----
For instructions on joining, leaving, or otherwise using the GSBN list, send
email to GSBN@...HELP in the SUBJECT line.  
- ----


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Checked by AVG Free Edition. 
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----------------------------------------------------------------------

Date: 10 Oct 2007 16:13:34 -0500
From: Graeme North ecodesign@...
Subject: Re: GSBN: Earth plasters

We have found the addition of pulped paper as a fine fibre very very good.
Its made either from office paper or newspaper - it can be made by throwing
soaked paper into a concrete mixer with lots of water and just letting it
roll until completely broken up , then draining off excess water before use.
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 that has
had a bit of straw left in it for a week or two to start to fizz is good as
well)  - there appears to be some enzymic reaction that takes place between
paper or ferment water and clay that helps workability and durability.

Paper pulp eliminates dusting from earth plasters - helpful especially if
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 finish and
it sticks like ...glue.
  
It is also very effective as an additive to earth bricks as well - increases
robustness, durability, and also lowers density giving better insulation.

The amount of paper pulp that can be added can be quite high  - we often use
up to around 30% or so by volume to plaster , and have made mud bricks with
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 rippings) or
straw, and 1 part paper pulp - very tough, very light, easy to work, and
looking promising.  Very good insulation, and very nice to use as gravity
increases - remember that there is plenty of evidence that gravity doubles
in strength very thirty years.

As to lime over earth - I1ve found it works well so far IF there is good
keying and wetting - if the initial earth is a cob type mix with lots of
(straw) fibre with plenty of fibres left hanging out of a rough surface,
then that is good too for tying the layers together.

I1ve just lost a patch off a bit of a small experimental earth plastered and
whitewashed straw wall where the earth plasters layers were not keyed well
together. Keying is good.

Best


Graeme,
Graeme North Architects,
49 Matthew Road,
RD1, Warkworth,
New Zealand 0981
Ph/fax +64 (0)9  4259305

ecodesign@...
www.ecodesign.co.nz



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----------------------------------------------------------------------

Date: 10 Oct 2007 20:28:39 -0500
From: thangmaker@...
Subject: Re: GSBN: Lime plaster problems

ah yes, on to Roman cement...=C2=A0=C2=A0 this is going to get good... come on
you experts.


=C2=A0


=C2=A0










- -----Original Message-----

From: Andy Horn 

To: 'GSBN' 

Sent: Wed, Oct 10 4:40 PM

Subject: GSBN: Lime plaster problems





Interestingly the locals in Kokstad who build with adobe ...but don't add 
sand to help with cracking will search to find a much rarer creamy coloured 
clay that can be found in the area to do their plaster coat with....and will 
then typically apply a lime wash to finish with. However they have not  learnt
to add sand so the walls are usually quite crazed with  cracks.....Sometimes
they also add cow dung which helps somewhat with the  cracking.    Not sure if
we can get any marble dust in that area,,,,but as I understand  it you would
want that in the earth plaster to get the bond to the lime  coat......   
Interestingly I hear from an archaeologist/conservator friend of mine that 
the Romans often used to add marble dust to their lime plaster. The other 
thing the Romans did was add fine fired brick or tile dust/powder to their 
mixes.....not sure what that was for or if it was simply instead of or when 
they ran short of sand???     Andy Horn    -----Original Message-----  From:
GSBN [<a  target="_blank" href="mailto:GSBN@...";>mailto:GSBN@...] On Behalf Of Athena &amp; Bill  Steen 
Sent: 08 October 2007 02:02 PM  To: GSBN  Subject: Re: GSBN:Re: Lime plaster
problems    Franko,  I think a major plus in your area is the calcium
component in the    caliche soils.  So therefore we have a chemical connection
going on    beside the mechanical.  And that is what is basically lacking with
   most soils.  One way to increase the possibility of a better chemical   
bond is to use marble aggregate instead of quartz sand.    B...  On Oct 7,
2007, at 2:50 PM, thangmaker@...:    > Thank you, Bill.  I have had
good results and no problems to date    > putting lime over earthen plaster
made with our native caliche    > clay.  We have done what Bill  >  >  >
suggests:  scratching the surface well and letting the earthen    > plaster
dry completely.  For those unfamiliar with caliche it    > occurs in the same
soil as limestone.  >  >  > It is the same basic material as lime (calcium
carbonate) but less    > dense and not well bonded to itself...flakey if you
will.      > Occasionally clay is found with this  >  >  > material and is the
best clay I have seen in terms of PI index (low    > expansion and
contraction).   This is the clay I wanted to use for    > the fire test last
year in San Antonio but as Matts pointed out it    > would not perform well in
a hot fire.   I am guessing the material    > is similar enough to lime
plaster that it both bonds well to it and    > their rate of movment and
reaction to moisture is similar.  >  >  >  >  >  > Cheers  >  >  > Frank Meyer
 >  >  > PS we are hosting a Natural Building Colloquim later this month    >
www.naturalbuildingtexas.org and have a great caliche clay pit on    > site. 
>  >  > -----Original Message-----  >  > From: Athena &amp; Bill Steen  >  > To:
GSBN  >  > Sent: Sun, Oct 7 12:11 PM  >  > 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=C3=A1s, Lleida, Espa=C3=B1a  > 
>> rikkinitzkin@...>  >> (0034)657 33 51 62  >  >>
www.casasdepaja.com (Red de Construcci=C3=B3n 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>  >  >>>
----  >  >>> For instructions on joining, leaving, or otherwise using the GSBN
   >>> >> list,  >  >>> send email to GSBN@...HELP in
the    >>> SUBJECT >> line.  >  >>>  >  >>> ----  >  >>>  >  >>>  >  >>>  > 
>>>  >  >>> ----  >  >>> For instructions on joining, leaving, or otherwise
using the GSBN    >>> >> list,  >  >>> send email to
GSBN@...HELP in the    >>> SUBJECT >> line.  >  >>>
----  >  >>  >  >> ----  >  >> For instructions on joining, leaving, or
otherwise using the GSBN    >> > list, send email to
GSBN@...HELP in the    >> > SUBJECT line.  >  >> ----
 >  >>  >  >  >  > Athena &amp; Bill Steen  >  > The Canelo Project  >  > HC1 Box
324  >  > Canelo/Elgin, AZ 85611  >  > absteen@...>  >
www.caneloproject.com  >  >  >  > ----  >  > For instructions on joining,
leaving, or otherwise using the GSBN    > list, send email to
GSBN@...HELP in the    > SUBJECT line. ----  >  >  > ______________________________________________________________________
  > __  > Email and AIM finally together. You've gotta check out free AOL    >
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Project  HC1 Box 324  Canelo/Elgin, AZ 85611  absteen@...
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