> -----Original Message-----
> From: John Horton [mailto:[log in to unmask]]
> Sent: Friday, August 11, 2000 3:02 PM
> To: [log in to unmask]
> Subject: RE: Lead paint regulations
>
>
> Question to John Mascaro:
>
> If the elastomeric acrylic grips the surface like a vise, is there also a
> danger of it yanking the old oil paint from the wood like a vise?
> I would be
> concerned with the extreme differences in the flexural strengths
> of the two
> types of paints. Of course, if the acrylic coating has that much integrity
> in itself, I guess it would remain freestanding -- until the surface is
> damaged. How thick is this coating applied?

Sorry to butt in.  Vice, which connotes a certain rigidity, is probably not
the right term.  How about "hold tight like ivy-suckers?"

The elastomerics have tremendous properties of adhesion, tensile strength
and elasticity.  It has the ability to move with the substrate, which is
desirable for a film.  So if the paint beneath is not moving, the
elastomeric should not be a problem.  The film _is_ thick, ranging in a
two-coat application up to 25 mil, and with three coats and a mesh fabric
(on a deteriorated metal roof, for instance) up to 50 mil or greater.  It is
vapor impermeable, which is in my mind is one drawback for using it on
siding where moisture migration is present.  But usually there are going to
be gaps on the underside of clapboards, which would probably mitigate the
moisture problems.  The other drawback as I see it is that if you already
have paint film build-up, and add the weight of this new thick film, that at
some point you are going to breach the mechanical ability of the underlying
paint film to hold fast, and the whole mess begins to delaminate from the
siding.
__________________________________________________
Dan Becker,  Executive Director      "Conformists die, but
Raleigh Historic                              heretics live on forever"
Districts Commission                             -- Elbert Hubbard
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