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Resin Coating on Cowling

R

rcarson

Well Known Member
RED ALERT, RED ALERT !!!!!!!!!!!!!!!! If you are at the point where you are about to mix epoxy resin and cut it one to one with acetone to fill in the pin holes with the mixture, DON'T DO IT !!!!!!!!!!!!!!!!!!!!
The manual says Van's uses West Systems but "any epoxy will do". This is not true. I used an aerospace epoxy manufactured by Fiber Glast in Ohio just outside of Dayton and it WOULD NOT CURE. Upon calling the manufacturer I was informed that the resin should never be cut with anything let alone acetone. West Systems is a marine epoxy and does not have the same chemical makeup. So far I have about 14 hours in scraping this goo off of the cowling and about $45.00 worth of sandpaper which simply loads up and has to be discarded. Save yourself some trouble and alot of time and call the manufacturer if it is not West Systems.
 
West system cut

I am told by some epoxy specialists in the boat biz
To cut or thin west with alcohol not acitone. Apparently acetone
Breaks down the bond.

I am considering mixing in some easy sanding 401 filler
To make it much easier to sand. Has anyone done this?
 
Guys, one more time.....don't thin epoxy. If you want thin epoxy, buy thin epoxy.
 
I strongly recommend you DO NOT use a microwave oven to heat the epoxy:eek:

Been there, done that.

Dont ask:mad:
 
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Epoxy

Why are you trying to thin epoxy? If it's too thick you have the wrong stuff or it's too cold.
Read the instructions.
 
epoxy

First of all that document is discussing adhesion to wood.
The first statement is "A question frequently posed to our technical staff is "can I thin West System epoxy so it will flow or penetrate better?" The answer to that question is "yes, but not without consequences." Many of the advantages of thinning epoxy are offset by disadvantages in other areas of epoxy performance."
Lastly why would you think this document supersedes the instructions that are included with the epoxy?
 
EZ-Poxy works with 50% acetone thinning just fine

It goes on like thin paint and seals the surface that already has the pin holes filled with microballoon & epoxy. Flew for a year that way then had it painted with Imron color and clear coat. Seven years later it still looks like new. I did that in southern California where it is fairly warm and dry and I put it on thin as was described in an RVator article.

Bob Axsom
 
Resin Coating

The manual from Van's instructs you to thin the epoxy one to one with acetone to allow a brush coating to fill pin holes in the cowling and that any epoxy will work. That is specifically why you are thinning the epoxy. If I were to question everything in the construction manual I would never complete the aircraft. Since Van's should be the authority on their own aircraft construction it follows that I would follow their instructions.
 
Mike S said:
I strongly recommend you DO NOT use a microwave oven to heat the epoxy:eek:

Been there, done that.

Dont ask:mad:
Click to expand...

I do it regularly, but only heat it for 10 seconds or less before mixing (heat the resin only) Works great.

But for pinhole filling I find it easier to spray high-build primer, then squeegee the resin, and wet sand after the epoxy cures. To accelerate curing I will drape an old blanket over the layup and throw a small space heater in.
 
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Resin only might work, I heated about 6 oz of mixed SafetyPoxyII for 30 seconds--------as I said, DONT do it that way:eek:
 
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Different Resins

Another way to get into trouble is not paying attention to the type of resin. There are polyester resins and epoxy resins. Either one uncured doesn't like the other uncured. So if you use one thinned to fill cowl interior pin holes, as I use West Systems + alcohol, don't top it with the other before the first completely cures. Welcome to gooey, sticky mess if you mix 'em.

John Siebold
 
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