[GSBN] lime plaster over compressed earth blocks
tracy at tactileplastering.com
Fri Apr 4 20:04:09 CDT 2014
I've just been revisiting the use of sodium and potassium silicates,
siloxanes etc. for use internally and topically in earthen renders. The
re-investigation on may part is due to a recent 'slip' erosion on a site
soil earthen exterior plaster on an exposed wind driven site in CA. I feel
like this topic emerges every few years in our discussions over that last
2+ decades as many can attest to.
Beyond our contemporary exploration of these materials I've been
researching earthen architecture and historical preservation techniques in
earth mortars and renders using these materials for water resistance.
There is some interesting information and a number of academic studies
that report better success with the use of the silicates/ siloxanes over
other materials such as oils, natural polymers, dungs, glues etc. They
have both been added to earthen mortars and renders. I even read a study
years ago regarding the preservation of the clay murals in the Magao caves.
I'll look for the study again but what I remember is in places of
delamination they injected a silicate material behind the plaster layer
under the paintings to slow/ remediate the seperation and keep it attached
to the wall.
I could go on but what I really want to know from this group is - are there
tests that have not been performed to answer some of these long term
questions regarding these materials? I'm heading into the studio sometime
in the next month or so to run some of my own with the materials and
research. I'll be running them with the site soil I am working with and of
course each site soil is different and may yield different results, but if
I could use these tests to answer a larger group context of questions
...... Anyone want to join me and run the same tests in different
And here is a fun 3 minute water test from our friends Ashley, at Dirt
Craft in Canada http://m.youtube.com/watch?v=q7cKpJ8ymOA. The test is
performed on a casein fortified EP using Eco House's (in Canada) product.
Would love to hear the answers to Derek's questions as well.
signing off from mud loving Nor CA.
Tracy (Vogel) Thieriot
Ochres & Oxides
On Friday, April 4, 2014, Frank Tettemer <frank at livingsol.com> wrote:
> Here's a story that might help address your query, Bruce.
> I agree with Graeme that design is the first solution. Design and plan to
> keep the walls as dry as possible.
> With climate change comes stronger, windier weather. Now we have to plan
> on the walls becoming wind-blown with rain, (in between periods of drought).
> In addition to adequate roof overhangs, eavestroughs, and proper site
> orientation, I do believe there is a good use for the magic of silicate
> dispersion paints, either from Bioshields in the States, or Eco-House in
> Canada. I'm certain there is an outlet in Europe, since that's where that
> technology came from. I've used it a number of times, as a colourant top
> dressing to plaster. The specs claim it to be vapour permeable and water
> resistant, (Like gortex for plaster). I'm a skeptic, so I prefer visual,
> tactile test results.
> Here's an inadvertent, but likely valuable test result:
> In 2004, we completed a straw bale home for a client in Ontario, Canada; a
> climate of high humidity, and frequent rain through the Spring, Summer, and
> Tina Therrien and Camel's Back Construction were on site, plastering, when
> someone discovered that over the weekend Cheryl and I had both quietly
> passed our birthdays.
> Tina and her crew made two "birthday cakes" for us, out of the plaster.
> They were so cute that we took them home, and set them on the deck to
> When obtaining a series of samples of different colours of Eco-House
> silicate dispersion paints, Cheryl decided to paint the "birthday cakes"
> with a variety of these pastel paints, as a colour sample.
> To make a short story longer, I set these samples out in the weather, (in
> 2004), on the deck, where they have remained to this day. Slightly
> chipped, and with the red colours slightly faded, these samples are
> perfectly intact today. See the attachment photo of them, that I took this
> morning ... yes, that's still three feet of snow in the background, with a
> shovel handle sticking out as a depth gauge.
> When it rains, the water beads up and runs off the surfaces of these
> samples, and appears not to be soaking in. When covered with snow, frost,
> ice, the samples have remained intact.
> I've liked these "cakes", so I've never immersed them into a tub of water,
> or attempted the "soak test" like Bill's friend, Paul Salas. I think they
> would turn back into the plaster components that they came from, and get
> pretty soggy. But standing up on the deck, in direct sun and rain, they
> have survived over Ten Years.
> So too have all the SB homes survived that we've treated with this
> silicate paint over the past decade. It does wear, yes, and probably will
> need a touch up coat after ten years.
> It's no real replacement for good overall design, but I am a believer in
> the help that they offer in the form of rainscreen cladding.
> For what it is worth,
> Frank Tettemer
> Living Sol ~ Building and Design
> 613 756 3884
> for what it is worth
> I have looked a many many walls treated with just about every magic potion
> known to man where people have tried to remedy what really is poor design
> in an attempt to try and reduce water ingress into earthen materials.
> Small samples of some potions can give impressive short term results, esp
> potassium silicate brews.
> In nearly every case, when dealing with a whole real building over several
> years, it also reduces moisture outfiltration (to reuse a great word) and
> the very least result, in by far the majority of cases I have looked at,
> is delamination of the treated surface layer, whether stabilised or not,
> if not more severe degradation, or leaking issues.
> If there already is a plaster delamination problem caused by moisture I
> would not be brave enough to suggest that any magic potion alone will solve
> The best performing surface treatments over natural earth are earth
> plasters, but they are prone to erosion, closely followed by lime plasters.
> Whitewash will also delaminate over natural earth.
> Keeping most of that darn rain off with roof overhangs appropriately sized
> for the conditions and /or rain screens is THE surefire treatment that
> really works.
> I really wish that there was a magic potion that really really worked.
> And that I had $10 for every time someone had asked me to name them one.
> Graeme North Architects
> 49 Matthew Road
> Warkworth 0981
> tel/fax +64 (0)9 4259305
> www.ecodesign.co.nz <http://www.ecodesign.co.nz>
> On 4/04/2014, at 1:54 PM, Bill Christensen <lists at sustainablesources.com<mailto:
> lists at sustainablesources.com>> wrote:
> Dang, I'm just catching up on my GSBN email tonight. Sorry we missed you!
> Alert me directly next time, will you?
> Paul Salas out of UNM told me about potassium silcate at one point, and
> gave me a quick demo as we passed through Santa Fe one time. He was
> looking into the same, and I believe he was trying to figure out if/how it
> was chemically changing the soil. It was definitely effective in reducing
> water problems - he had a small adobe that had been treated and another of
> the same soil which hadn't, and when he dropped them both in water the
> untreated one came apart. The treated one came out whole.
> I suspect a brush-on application would help the plaster hang together as a
> monolithic sheet. It would also reduce water infiltration, I believe. Of
> course, it might also reduce outfiltration... If it holds water in the
> untreated interior, well, I don't need to spell out for you what could
> result. You're a smart guy.
> On 3/26/14 9:59 AM, Bruce EBNet wrote:
> I'm trying to help a builder near Austin, Texas with a delimitation
> problem on a 7 year old building. He says he has since learned to use
> potassium silicate as a brush-on stabilizer for the blocks, helps the
> plaster hang on.
> Thoughts? Experiences?
> Austin folks: I'm coming into town tonight. Dinner?
> Bruce King
> www.ecobuildnetwork.org <http://www.ecobuildnetwork.org/>
> (415) 987-7271
> Skype: brucekingokok
> Twitter: @brucekinggreen
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