> -----Original Message-----
> From: M. P. Edison [mailto:[log in to unmask]]
> Sent: Tuesday, October 29, 2002 10:42 PM
> Subject: Re: Coating analysis interpretation
> 
> 

> It seems to me a fair conclusion that this stuff is some sort
> of latex 
> paint. There is good latex paint and cheap latex paint. We don't know 
> which variety this particular one is. If the purpose of the paint is 
> decorative, why apply the equivalent of 10 coats at once? One or two 
> coats now with a refresher every 10 - 15 years would make more sense. 
> If there is some other reason for using such a thick paint, I guess I 
> just don't get it from the information provided.

I would tend to agree with you on the face of it, but from my inspection
of the material in situ, it struck me as much MUCH harder than one would
expect a really thick coat of latex paint to be. There was another
product back in the mid-80s, "Siding in a Can," that we were able to get
specific product data for, and it _was_ a thick latex paint. This
material presents a different appearance than that product did. My
nagging intuition, which admittedly is all I have to go on, is that
"Spray on Siding" is more akin to a petrochemical-based sprayable
plastic coating. It had no give at all under the Official Fingernail
Press Test, which I would expect a thick latex to have some give.
Perhaps my sense of the hardness of latex is at error.

I've never thought of paint as decorative, and it steams me when I see
painters treat it as a decorative color change only. It is first and
foremost a protective coating, which has a collateral benefit of being
able to have color applied to a decorative end. But the idea of a
continuous coating, with care exercised in ensuring that caulk is well
done, that the coating is seamless and adequate in thickness for the
purpose of protecting the substrate from water infiltration, seems to
elude a lot of people. So I guess the reason for a thick coating, if in
fact it has vapor permeability, would be a higher percentage assurance
of adequate protection.

So then I get back to the failure mode discussion and the reversibility
issue; if it's plastic and it cracks, what the hell do we have then? And
what do we do? Does it scrape off like paint when it finally reaches its
point of adhesion failure? Only time will tell.

Cheers,

___________________________________________________
Dan Becker,  Exec. Dir.     "What's this? Fan mail
Raleigh Historic             from some flounder?"
Districts Commission         - Bullwinkle J. Moose
[log in to unmask] 
919/890-3678

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