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Re: GSBN: Lime plaster problems



--On Wednesday, September 26, 2007 6:37 PM +0000 Andy Horn
andy@... wrote:

On the first morning after applying the plaster the weather
turned at night and brought frost...2 months ahead of when it is
normally expected! There were sheets of ice in the water buckets
that morning!

I am curious about the comment that this freeze was 2 months _ahead_
of the expectation.  I'm thinking that, as of the date of Andy's
message in late September, South Africa is moving into Spring and
looking forward to the warmer temperatures of summer.  Perhaps the
plaster was applied in April or May?  Andy, can you clarify what
temperatures were "normal" when the plaster was applied, what the
normal freezing season is like (and when), and what weather you
expect from now into the next few months, when you will be
re-applying the plaster?

A few more questions come to mind from your description of the
problem.  There is a great deal of variation between different lime
sources/stocks.  Is there an alternative to hydrated lime that you
used?  Is this brand of lime generally reliable when used in the
manner that you applied it?  Is it possible that the bags of lime
which you used had been stored improperly or were very old?  Does
soaking this specific lime for days or weeks prior to application
have a significant positive effect on this lime's working properties?
(While hydrated lime is slaked at the factory, some members of the SB
lists report that their hydrated limes get better with soaking).  Did
anyone do test samples of this lime, using your mix and application
techniques?

You mention adding a small amount of adobe soil to the render mix.
Soils vary tremendously, and some of them are not happy companions
with lime.  Some soils and mix ratios can decrease the strength
and/or adhesion of the render.  Is there a compelling reason to
include the soil in your mix?  If so, testing various mixes and
ratios could be enlightening.  Please tell us more about how much
adobe soil was added, and if possible, what the pH of the soil is.

Derek


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@...