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Aircraft Epoxy, Marine Epoxy what's the difference?


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Aircraft Epoxy, Marine Epoxy what's the difference?
I am starting the research for building a LongEZ or Cozy Mk IV. The groups and instructions all talk about "Aircraft Rated Epoxy".

What's the difference between aircraft and marine epoxies?

I understand the stresses are somewhat different, flex, shear and stress vs pounding a 2 - 3,000+ lb boat into crashing waves at 30- 80 mph.

I can buy marine epoxy "wholesale" for $40 per gallon, vs paying retail (from spruce) for aircraft epoxy.
Could sure use some help here.

New Facebook Group for Cozy Mk IV Pilots & Builders


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Aircraft Epoxy, Marine Epoxy what's the difference?...

Nothing, because there's no such thing as "Aircraft" epoxy or "Marine" epoxy. There are epoxies that designers have chosen based on their properties to ensure that the specifications of the device in question (aircraft or boat) will be met. If you use an epoxy that was not approved by the designer, then maybe those specifications won't be met, and you may either fall into the water or out of the sky.


Since you're interested in LE's or COZY's, there is a clear list of approved epoxies that can/should be used, and you should pay attention to it, particularly to the fact that the best epoxy for the strakes/fuel tanks is the EZ10/87 due to its fuel resistance capabilities. There are reasons NOT to use particular epoxies as well - the West 105/205/206 are NOT approved due to the low pot life and high exotherm probability on structural (read thick) layups.


In the grand scheme of things, the cost of the epoxy is a tiny percentage of the total cost of the aircraft - don't skimp here.

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