On Tue, 9 Jul 2019 14:20:14 -0500, Terry Coombs
wrote:


* Live and learn , it's expensive ! So about 14 years ago we bought a
camping trailer . One of those super lightweight units . The problem is
, nobody ever said a word about checking the caulking (roof mostly)
every year or two ... now this unit is made of bonded foam/plywood
panels with 1 1/2" thin-wall aluminum square tube framing . And there's
water damage that has caused the plywood to delaminate . I've repaired
the floor panels and laminated a layer of 3/8" plywood using a
latex-based engineered wood adhesive . Next step is regluing those
delaminated plywood panels . The interior ones I'm going to just replace
using the same/similar water-soluble(when uncured) adhesives . The
outside skin is another matter entirely . I have purchased both epoxy
and polyester resins and have formulated a plan to hold the panels
firmly against the substrate (the styrofoam) while the resin cures .
HOWEVER I have been cautioned by a local (kinda) RV repair place that
the resin MAY cause damage to the foam core - like dissolve it . I know
there are at least a couple of folks here with chemical backgrounds ,
I'm looking for an answer - is the resin going to dissolve the foam
cores of these structural panels ?

Polyester resin will disolve styrene. Epoxy will not

A corollary question is : are all
styrofoams created equal ? I have several pieces of styrofoam insulating
board leftover/used and removed , etc that I can use for testing ,
ass/u/ming that it's all made from the same stuff . FWIW it looks like
the original bonding agent was a rubbery adhesive ,
There is ipen cell (blown) expanded styrene and closed cell expanded
styrene. Otherwise known as "bead board" and" Styrofoam SM". Both are
styrene and will be disolved by the solvents in plyester resin. There
are also IsoFoam, urethane foam, andseveral other foam board products
that will stand up to polyester - but they are not as commonly used in
things like travel trailers. Take a small chunk and put it into a jar
of gasoline. If it melts, DO NOT use polyester resin!!!
I'm guessing a
latex-based contact type adhesive .* And I'm working to a deadline - my
wife wants to go visit her old and sickly mother later this month . I
can't leave the dog home and Max would run her mother bugnuts crazy in
under an hour ... and there ain't a motel I know of that'll let us have
a 70 pound dog in the room . I guess I could just send her off to
Kentucky alone and Max and I could stay home ... which would suit me
just fine , but y'all know how women can be about this sort of thing .