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GSBN:Siloxane - Potassium Silicate

Dear GSBN members,

Sorry for my reply on Derrek Roff's message about Wiki.  I was a bit
lost in my mailbox and replied to a mail sent by Derrek ages ago.

During the ISBBC I was very impressed by the presentation of 'ECO House'
paints by Jeff Kennett. They commercialize a mineral paint that acts
somewhat as a limewash (in that it helps the plaster resist to rain) but
holds on to it's substrate a whole lot better. In fact, that is not
totally correct, their product goes INTO the substrate. I was even more
impressed that they actually mention on their products what they
contain. Something I think every manufacturer should be obliged to.
Anyway, after the presentation I had a very interesting conversation
with their director (of whom I forgot the name) and he confirmed me that
the main agent is POTASSIUM silicate (not SODIUM silicate). Why am I
talking about all this? Because I'm searching for a transparent product
that can make an earthen plaster more/very rain resistant while keeping
it 'breathing'.

Bill Steen told me some years ago that 'waterglass' (potassium silicate)
can make earth plaster (more) rain resistant but I don't remember if he
told me in what proportion it should be used and how to apply it. The
Ecohouse talk brought this back to my memory and the director was so
kind as to tell me one can use potassium silicate if diluted with 4
parts unmineralized (with an osmoser for instance) water for 1 part
potassium silicate.

Back in France I found the potassium silicate (by the way on the label
it says to wear protective gloves and glasses and to wash the stuff of
your skin if you touch it) and I applied it yesterday (with a brush). I
noticed, when I applied a second layer, that the earth would not rub off
anymore when I insisted. Some whitish areas appeared once dry.

In the evening I continued to read Bruce King's new bible "Design of SB
Buildings'(*) and discovered 'siloxane'.

I googled a bit on siloxane and found some interesting stuff:
<a  target="_blank" href="http://www.ecobuildnetwork.org/pdfs/Straube_Moisture_Tests.pdf";>http://www.ecobuildnetwork.org/pdfs/Straube_Moisture_Tests.pdf</a>
<a  target="_blank" href="http://www.cmhc-schl.gc.ca/publications/en/rh-pr/tech/00-132_e.pdf";>http://www.cmhc-schl.gc.ca/publications/en/rh-pr/tech/00-132_e.pdf</a>

Today we have a clear blue sky so I simulated some rain with the garden
hose. The earth plaster now resists very well to water (nothing came
down while showering it) even though the plaster has some cracks and has
already weathered somewhat before I applied the potassium silicate. When
I put the 'full concentrated blast' on it it did make a hole in the
plaster (where I directed it on a pothole). It did also dig into the
plaster that received 2 layers of potassium silicate but it did take
significantly longer.

This experimenting leaves me with some questions :
Does any of you have experience with potassium silicate and/or siloxane?
How do you apply them? Would spraying work better? How many layers?
Does anyone have info/thoughts on the ecological footprints of these
Anyone have any experience with the transparent casein/lime mix that
Gernot Minke mentions in his book?
Did any of you make paint for outside use by mixing finely sifted earth
or clay with any of these additives?
Is it a good idea to mix potassium silicate and/or siloxane in the
finish plaster before applying the plaster? Should one than wear gloves?
Is siloxane the same thing as potassium silicate?
Any other suggestions/products?


(*) Thank Bruce, it is a great resource!

Lars Keller a ?crit :
Makes sense. Shared quality information rarely has sideeffects.
By the way: good luck to us all regarding the US midterm elections today.
Lars Keller

2006/11/6, Andr&eacute; de Bouter forum@...:

I totally agree with Derek.


Derek Roff a ?crit :
> Duncan's wiki might be a useful repository for this kind of
> As mentioned in a related posting, we need both books and more dynamic
> references for changing information.  As the Strawbale wiki develops, I
> think it can meet several reference and information sharing needs.
> Derek
> --On Wednesday, March 8, 2006 12:47 PM -0500 Chris Magwood
> cmagwood@... wrote:
>> On a subject related to details talk:
>> My own details book is reaching the end of its shelf life. I'm
>> contributing to the CASBA book, which I think will be a great
>> resource. However, I'm also contemplating doing an update of my book
>> but offering it for free on the web (or by donation, or some such
>> thing). Perhaps there is a place for a TLS/GSBN-sponsored site on
>> which details are posted visually and accompanied by text/debate? I
>> don't want to undermine the CASBA effort at all, but since there are
>> so many possibilities and variations and changes happen faster than
>> books can be published, perhaps we'd all be doing the whole movement
>> some good by making an open-to-the-public details shop?
>> If there's any interest in this, I'm happy to throw the contents of
>> my details book (plus the revisions I'm working on) into the public
>> domain as a place to start.
>> Chris
> Derek Roff
> Language Learning Center
> Ortega Hall 129, MSC03-2100
> University of New Mexico
> Albuquerque, NM 87131-0001
> 505/277-7368, fax 505/277-3885
> Internet: derek@...
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