>-----Original Message----- >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
>it looks like the problem is >under control. >Basically, it appears to be the wax. Or, more correctly the waxing >technique. I have been following this thread, or at least the apparently small part of this thread that has been publicly posted. I had not posted a response since I couldn't think of what was causing your problem. Based on the few publicly posted responses, I still don't have any understanding of the problem and especially can't imagine how any manipulation of any sort of wax can cause the problems you described. My purpose in responding now is to prevent the over complication of what should be a very simple process. When vacuum bagging solid core wings, the waxing of the mylars is something which should be very simple and nearly impossible to do wrong. You simply need to apply some carnauba wax, let it dry, and then buff it with a paper towel until shiny. The length of time you wait between application and buffing does not matter as long as the wax is dry enough so as not to just get wiped off again. No special drying techniques should be required and no long waiting periods before painting or bagging should be required. I commonly paint mylars immediately after buffing the wax or in the case of unpainted mylars, I commonly do layups immediately after buffing the wax. I allow the Krylon paint to dry overnight before doing a layup but only because it produces a better finish quality on the painted surface if the paint is fully dry before unbagging the wing and pulling the mylars. After going back and reviewing the earlier posts in this thread I can offer some ideas as to what the problem may really be although I still can't come up with an answer that fully fits the description of the problem. The most perplexing aspect of the stated problem is the statement ; "1/32 to 1/16 inch deep". No imperfection in a finished wing that I have ever seen comes close to that kind of depth. I'll describe some things that can cause imperfections on a smaller scale; I noticed in the original post that you were using West Systems 205 hardener. Perhaps you meant to say 206 hardener. The 206 hardener is appropriate for vac bagging. The use of 205 (much faster acting) hardener could cause a few problems; If you warm the epoxy too much and mix it on a paper plate, then a skin of cured epoxy can form on top of the puddle of epoxy. When you then use a foam roller to spread this epoxy on the mylars or the layup, the skin of cured epoxy gets broken up into little stringy bits that are mixed in with the rest of the epoxy. There was a time when I would see these little tiny unexplained stringy things in my unpainted hand launch wings. I finally figured out what was causing it and turned down the heat on my epoxy heater. If you use a similar method (learned from my video) but mistakenly use 205 hardener, it is easy to guess that you might be experiencing this problem and it might be of a greater magnitude (larger stringy things?) than what I have seen. Another problem can happen with painted mylars. If the epoxy gets too thick during the layup process and you are rolling the layup with a foam roller to spread the epoxy then the paint can be lifted off the mylar. This happens because the epoxy is so thick that the layup sticks too heavily to the foam roller and wants to wrap itself around the roller as you roll the layup. Once the paint lifts, air gets in between the paint and the mylar, and becomes trapped there since both the paint and mylar are non-porous. The trapped air bubbles cause a rough area in the finished wing since the air acts just like a foreign object in the bagging materials and gets forced into the wing under vacuum. This problem would once again be more likely to happen if you use a faster hardener. Jeff Stiefel posted the suggestion that I was most tempted to post myself. Whenever you see unexplained indentations in your finished wings, you should immediately think about the possibility of hard bits of crud (frequently bits of cured epoxy from previous bagging operations) in your bagging materials. Even a tiny nit of cured epoxy can cause a big dent in the wing when it is forced against the outside of the mylar under vacuum. These nits hide very easily in the breather cloth and are easy to overlook. I really wish people would post suggestions publicly. Perhaps I have something to learn myself about this. From the little bit that was posted publicly, I am left wondering how the inappropriate use of wax causes 1/16" indentations in a vac bagged wing. Phil RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off.
