Skim Coating the Fuselage Bottom
I can't believe it, but it's the end of January '06 and winter still hadn't really arrived. It even hit 67 degrees one day! I played hooky from work, blasted out to the airport, and skim-coated the fuselage bottom, sides, and lower strake fairings. I wasn't really prepared to do the skim coating THAT DAY. I had only contoured to 40 grit at this point. I had not yet contoured to 80 grit like I usually do. But I decided to skim-coat anyway and see what happened. I had only enough time to put on three coats before blasting off to church for Monday night Bible Study. (Somebody's gotta thank the Lord for blessing us with such warm winter weather!!)
I'm happy to report that three coats was enough to fill the 40 grit scratches, all pinholes, and all but the deepest and biggest of holes and gouges. This raw epoxy finishing technique really, really works. I'd still recommend contouring to 80 grit before skim-coating, but you can also stop at 36-40 grit and be confident that the skim coats will cover adequately.
I did try thickening the epoxy up a bit with cabosil. I've heard of others having one-coat success with lots of cabo, but I was unwilling to mix too much in. Well...I didn't like it. The mixture gets thick and the cabo keeps it from flowing and leveling out. It doesn't flow into pinholes as easily either. You have to work it into holes more than with raw. The raw flows right in with little effort other than squeegeeing. Also, the ridges that form off the squeegee while scraping tend to be more pronounced (higher) than raw, and they take more effort to sand off later. Oh....cabo makes the epoxy MUCH HARDER to sand off. So I question how much time is really saved with one-coat cabo versus the sanding required afterwards? So, for me, no thanx. I guess I'm not a one-coat cabo kind of guy. I won't use a cabo mix on horizontal surfaces anymore. I'll stick to using cabo only in small quantities to keep the raw from running on vertical surfaces.