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Re: GSBN: Earth plasters
> Hi Bill and others - thanks
> I agree totally that long mixing and aging is good for plasters.
> And sometimes yes we long for a bit of dehydrated climate Ð esp when the mould
> starts growing on us!
> An earth/straw house actually makes one hell of a difference in comfort in
> this soggy climate Ð no more condensation on even single glazed windows (with
> passive solar design to trap some heat into the mass of the house) Ð no more
> mould on items such as leather shoes Ð plenty of spiders to share the house
> with -
> Be really keen to hear how you find EM Ð IÕve just discovered it for the
> garden Ð it seems to be magic Ð it may take away that good old fermenting
> As to significant thermal mass in straw houses Ð IÕm a bit of a fan myself of
> straw for exterior walls, earth for interior walls and floor, and donÕt try
> and pursue much out of the earth plasters where it is going to be pretty
> minimal anyway Ð and of course only the final plaster of only a few mm thick
> needs the paper additive anyway come to that.
> And - IÕve never found swelling of cellulose fibres to be an issue, even with
> quite high percentages Ð its really saturated when we use it Ð esp if its been
> sitting a while Ð and anecdotally Ð a building near here that burned down had
> the firemen puzzled because the dry wall was in much better shape than the
> firemen expected to see after a fire Ð the clay/paper plaster had added
> significant extra protection.
> Finally - Limewash over clay- yes toughens up the surface no end - -however I
> have found on experimental and historic walls that IF the wall gets so wet
> that water gets into the underlying earth plaster, differential swelling takes
> place and the whitewash spalls off in my humble experience. If the walls are
> getting this wet probably something wrong with the design anyway.
> 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.
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