Wayne Hicks Posted June 13, 2005 Share Posted June 13, 2005 I recently read about the finishing technique that Cory Bird used on his OSH grand champion Symmetry. The technique is dry micro, contour to 36 grit (yes, 36 grit), then skim coat and squeegee up to 5 successive coats of pure epoxy (yes, pure epoxy) to fill all pin holes and scratches. Curious, I tried a variant of it this weekend on the bottom of my wing. 4 pinholes TOTAL! Except for two small low spots near the aileron spars, I was almost ready for paint on the very first try. I am so psyched I can hardly stand it. If I was starting from scratch I would definitely give the full technique a try! I was already contoured to 120 grit on my wings when I came across the article, so I didn’t use that many coats. In my "test case", I applied the pure WEST with a roller, waited 10 minutes, the squeegeed it all off. The pinholes were almost filled. So I applied another layer, this time lightly squeegeeing to leave a very thin layer. I probably left on too much WEST. I need to find the balance between scraping it all off and leaving barely enough on. Anyway, I started sanding off the WEST. True, it was a little hard to sand off. But a MIRACULOUS thing occurred. Almost all the pinholes and large scratches got filled. And I'm talking about very big pinholes, like the size of small peas. Even more miraculous, because the WEST is so tough, my 3-foot sanding board (100 grit, then 120 grit) "cut" the tops off the most inconspicuous of high spots that my first contour to 120 never caught! I continued to sand, sand, sand until all the WEST was almost, almost, almost sanded away. Steve (an exceptional hangar mate if ever there was one) sprayed the wing with primer. Like I said above, I sanded it off and was rewarded with a wing bottom that had only 4 pinholes TOTAL. For test comparison, I didn't WEST the lower winglet. Just sprayed primer over it. Of course, it was loaded with pin holes. So what does this all mean? Since this is the first time I've ever filled, sanded, and primered ANYTHING, I have no basis for comparison. But I can vouch that skimming with WEST really does fill scratches and pinholes of all sizes. And if you're an aggressive sander like me (meaning, I have no patience, no finesse!), the hard coat left by the WEST helped me to achieve an even better contoured finish. The other obvious benefit is leaving the tiniest of WEST layer helps to harden the micro. I've heard others say that this helps prevent print-through later on in life. Quote Wayne Hicks Cozy IV Plans #678 http://www.ez.org/pages/waynehicks Link to comment Share on other sites More sharing options...
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