[NSRCA-discussion] epoxy question

[Dr. Mike Harrison]

I have read with interest all the comments and some of you have educated me on this issue.  If I may, I will share what I have learned.

1.  Thinning the epoxy saves no weight by evaporation.  There is virtually no evaporation and no weight loss-a big time erroneous assumption on my part.  So if you mix 2 ounces of epoxy and add 2 ounces of thinner and put it all on the airplane, you have added 4 ounces to the airplane.  
2.  The properties of the epoxy are changed-it becomes rubbery.
3.  Changing the properties is not an issue regarding finishing the airplane(painting)
4.  Using thinned epoxy is fine for applying glass cloth.
5.  I have tried MEK(epoxy thinner), denatured alcohol, 91%alcohol, acetone.  My preference is denatured alcohol because it is the safest and most economical, I think.  I thought MEK would be the answer.  It is the worst of the bunch.  
6.  The best way to glass surfaces is to thin the epoxy and apply as sparingly as possible.  A way to do that is to apply and wipe off excess with paper towels.  
7.  It is almost exactly 2 ounces to glass a wing panel complete, so 4 ounces for a whole wing.  About 2 ounces for a stab.  Properly done wings and stab glassed and painted is 2-2.5 times the weight of monokote.  
8.  A second thinned coat of epoxy on the glassed wing is .75 ounces each wing panel-1.5 oz total.


Pick your poison.

Later,
Mike
 
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