[NSRCA-discussion] thinning epoxy, how?

[J N Hiller]

Thank you for the very informative information. I have never used epoxy for
fuel proofing. I've used Polyester finishing resin and K&B epoxy paint until
I ran out and recently Formula-U Polyurethane paint. What are your thoughts
on these alternate materials?
I find fuel proof compromising gouges are more visible using colored paint
rather than a clear coating.
Jim Hiller


-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of Gray E Fowler
Sent: Monday, March 16, 2009 6:24 AM
To: General pattern discussion
Subject: Re: [NSRCA-discussion] thinning epoxy, how?


Fast curing epoxy adhesives such as the 30 minute are a bad initial choice.
I realize that thousands have used it in these applications, but that still
does not make it a good choice. The non reactive components in the fast
epoxy plasticize with age and methanol and nitro will seriously degrade the
stuff. Using one of the thinner slower curing laminating resins will require
less solvent, if any and provide a much longer lasting barrier. Any solvent
added to an epoxy needs to evaporate completely or you will created a
problem. Denatured alcohol (ethanol) evaporates very slowly. Cutting a fast
cure epoxy with a slow evaporating solvent is a recipe for trapping alot of
solvent, making the chemical resistant even worse. Methanol evaporates much
faster and epoxy is much more soluable in methanol. Be very careful using
ketone solvents (acetone, MEK) or aromatics (Toluene, Xylene) because many
kit manufacturers use styrofoam as a core material that will be destroyed in
seconds with  all solvents except the alcohols.

SO!

1. Use a thin slower cure laminating resin
2. Use Acetone, MEK or Laquer thinner
3. NO puddles, super thin coat
4. Alcohols if you have a styrofoam core
5. rule #3 again

6. If you only need the plane to last 1 year, then use 15 minute epoxy and
do not worry..it will last 1 year or so.

Gray Fowler
Senior Principal Chemical Engineer
Radomes and Specialty Apertures
Technical Staff Composites Engineering
Raytheon


"J Shu" <jshulman at cfl.rr.com>
Sent by: nsrca-discussion-bounces at lists.nsrca.org
03/15/2009 02:15 AM
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[NSRCA-discussion] thinning epoxy, how?






I want to add another layer of sealer to the firewall and tunnel on my
plane... what's the best way to do it with epoxy? I've got 30
minute but not sure how to thin it to seal it.

Regards,
Jason
www.shulmanaviation.com
www.composite-arf.com
[attachment "IMG_4498 (500 x 299).jpg" deleted by Gray E Fowler/US/Raytheon]
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