[NSRCA-discussion] epoxy question

[rcmaster199 at aol.com]

For what it's worth I'll share what I have learned also. My observations in bold below


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MattK










-----Original Message-----

From: Dr. Mike Harrison 

To: NSRCA Mailing List 

Sent: Fri, Nov 23 2:58 PM

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.


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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.? This isn't true for thin layers


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. The weight of the thinner is no consequence. It flashes just fine due to thin section


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.? Use Klass Kote clear epoxy paint. Better than old K&B and lighter than thinned epoxy. 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.? I use silkspan in my covering and finishing. Painting cost nothing in terms of weight gain over MK. But care must be taken every step. MK is relatively easy; Silkspanning and painting to the same weight is more difficult and labor intensive


8.? A second thinned coat of epoxy on the glassed wing is .75 ounces each wing panel-1.5 oz total.


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Pick your poison.


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Later,


Mike


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