[NSRCA-discussion] epoxy question

[Jay Marshall]

Fantastic info!

I note that the instructions on the Z-Poxy Finishing Epoxy (PT-40) for
applying fiberglass cloth make no mention of using a thinner.

 

Jay Marshall 

-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Dr. Mike
Harrison
Sent: Friday, November 23, 2007 2:57 PM
To: NSRCA Mailing List
Subject: [NSRCA-discussion] epoxy question

 

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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