Chapter 25 - Finishing
Sand, sand, sand. It's the composite builder's lot in life. I filled and sanded as I went, so as not to have a huge amount of it to do at the end. The downside of this is that occasionally I had to redo work as I dripped epoxy on smooth surfaces, or needed to plastic-wire-brush an area to remove filler and rough it up to attach a new layer. But mostly, I'd recommend sanding as you go.
I tried both epoxy and micro, and Stitts SuperFil, as fillers. Both are light and sandable, and of course epoxy-based. With the Stitts, I had some mixing problems, leading to flaking parts later. Since I was using EZ-Poxy, both of these needed overnight cure before they could be sanded; I never tried using the West system. I also never experimented with Cab-O-Sil.
For paint, I used Smooth Prime, by Stitts Poly-Fiber, to prime the airplane. The stuff is water-based, non-toxic, fills pinholes like a dream, and just rolls on with a roller!
I decided to get started early; as you've seen from the pictures, I experimented on the fuselage underside a long time ago. Then put it off when I realized that primer that site long-term collects oils, and thus doesn't adhere as well with the top coat. After a long hiatus, I resumed painting; with everything but the cowl built, I separated the control surfaces and canard, and primed them completely:
Sounds so easy, doesn't it? Roll on three coats, spend an eternity sanding smooth, curse as you sand through near a corner somewhere. Repeat ad nauseum. Eventually, I stopped sanding through.
However, experimentation showed that the gloss coat didn't roll on nearly so well. I'd have to spray. One el cheapo hardware-store HVLP sprayer later, I was in business. I had to use it in pressure-sprayer mode, not siphon mode...I'd gotten a sprayer that said it did both, though, alarmingly, it popped out the recessed butt of the spray bottle the first time I pressurized it. Oh well, it's a pressure-worthy bottle now.
About two and a half eternities later, I had an airplane, primed and sanded, cleaned and ready for top coat.
There was no way I would ever get the hangar clean enough to spray the top coat. I hired the job out. After some delay, I got good parts back!