Dan,

Objective note on vapor permeability:

The Sealants Waterproofing and Restoration Institute (SWR) has developed a 
testing and validation protocol for wall coatings. Part of their protocol 
involves ASTM E96 testing of permeability at the specified film 
thickness/application rate for each product being evaluated. The testing is 
all done by DL Laboratories in New York City, and they are supposed to test 
actual production materials taken off the distributor's store shelf, rather 
than samples prepared specially by the manufacturers.

So my point is that while some heavy acrylic latex elastomeric coatings may 
only test out at 3-5 perms (still in the breathable range), others test out at 
10 times that rate. The one of ours we had tested, applied in two coats/69% 
solids/100 sq.ft. per gal. tested out at 30.8 perms. Our internal testing came 
up a little higher (42 perms), but lab-to-lab reproducibility of permeability 
test data is notoriously bad, varying by as much as 75%. A popular silicate 
coating also tested by DL outide of the SWR program came in at 18 perms, and 
that manufacturer claims something like 98 or 99% breathability.

I am not a big fan of reinforcement in general, but clearly, as you build more 
film to saturate the mesh, permeability is reduced. But to answer the 
question, yes, you can formulate coatings of this type for higher or lower 
permeability, and that is a key difference between properly formulated 
elastomeric wall coatings and elastomeric roof coatings, even if they share 
very similar chemistry.

As for your "Rhino Truth-O-Meter" flashing you all kinds of warnings, I would 
say your instincts are right on target. Personally, I can't stomach this kind 
of marketing drivel. 

Mike E.
---------- Original Message -----------
From: "Becker, Dan" <[log in to unmask]>
To: [log in to unmask]
Sent: Thu, 4 May 2006 10:06:38 -0400
Subject: Re: [BP] Eco-Armour Cote/Rhino Shield? WTF?

> > -----Original Message-----
> > From: edison
> > Sent: Wednesday, May 03, 2006 6:13 PM
 I 
> > have seen elastomeric coatings (including a couple of ours) 
> > out-breathe some 
> > of the so-called 99% breathable silicate coatings. Pore 
> > structure, pigment 
> > volume concentrations, microfoam and film thickness are 
> > factors that affect 
> > moisture vapor transmission rates. Some elastomerics are 
> > extremely breathable, 
> > some aren't.
> 
> Is this true of 100% fluid-applied acrylic elastomerics? Can vapor
> permeability be engineered into those films? The products that I have
> seen are intended to serve as waterproofing membranes, usually on roofs
> or concrete. Is vapor permeability possible at the thickness rates they
> are recommended for? (15 mils minimum, up to 50 mils when incorporating
> reinforcing mesh.) Is vapor permeability a desirable characteristic for
> such films? 
> 
> The little bit of info on the Rhino Shield site suggests it is a
> two-part application with an initial "adhesive base coat" layer. I too
> would like to see the technical specs, but having fended off some of 
> the products that John Leeke refers too, they are loathe to provide 
> any info about what it really is ("proprietary information"). So in 
> the absence of being able to "show you the data," I will choose to 
> remain highly suspicious and skeptical of any so-called "miracle 
> lifetime solution."
> 

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