[NSRCA-discussion] thinning epoxy, how?

[Gray E Fowler]

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> 
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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
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