I finally had some good fortune with the blue paint project. With the legs and body, I have been struggling to get good results on the so-called Krider Blue method--primer, Rustoleum Cobalt Metallic Blue or Deep Metallic Purple, Blue Anodized, and Clear Coat, in that order. All of these paints have pretty different properties when you apply it. The primer is forgiving, but the rest have all screwed up on me in one form or another, and the temperature and humidity are other variables that make the process unstable and unpredictable.
I've been prepping all of the dome pieces for painting for several days now. And when I painted them yesterday, I finally got some good, deep luster results, I think. At least the results are good for me. These pictures don't really show it, but the blue anodized layered on top of the cobalt metallic worked out well--the color is a deep vibrant blue. The theory is that you put your last coat of metallic on and then wait ten minutes to put on the blue anodized. The blue anodized is supposed to mix with the metallic and make the coat deep and reflective. Mine's pretty good for me.
Here's some lessons I think I've learned so far:
1) Read the labels on the paints. Some of these can be recoated immediately, some within 30 minutes, some within an hour, and others only after 24 hours. I take it that there are different curing times for the chemical formulas.
2) I'm impatient and want good results. I have to consciously make a plan for the coats and then discipline myself to stay to it without messing with the order, dry times, or parts.
3) The ten minute period between metallic and anodized is a rough number. When it's hot, I did it sooner--5-8 minutes. And I used a kitchen timer to really get this close.
4) The blue anodized (can't remember the brand--I got it at Kragen) is peculiar stuff. It goes on very thin and the nozzle clogs easily so it was hard to get a good even coat with it, and you can't really see when you have because it's kind of clear. I scraped the nozzle hole clean mid coat yesterday and kept shaking the stuff and managed to start getting an even coat.
5) The balance between too much and too little for a coat is really tricky for me. With the blue anodized the coat was looking grainy. I waited 15 or 20 minutes at one point and then put another coat on that started going on wetter and more even. That's when the coats seemed to merge and starting looking like I thought they should.
6) The aluminum parts have to be primed with self-etching primer from the auto parts store. This stuff eats away at the surface a bit and gets a good bond. I put on a few thin coats of this with lots of sanding to 400 grit before, and then light sanding with 400 between coats to get it smooth. Seems to have worked. I could still see some spin grooves on the pieces after the 400, but I knew the paint would cover it.
7) Temperature ranges for the paints are 60-90 or so. I tried to follow that. It's August so I did some painting early in the morning when it was cool and there was no wind. I don't think I got any good results when I painted when it was hotter than 85, except maybe with the primers.
8) Clear coats, as I have said before, just suck. I had several very good paint jobs with a lot of work in them just wrecked by trying to clear coat them. It would run or lay on all grainy or something. Made me want kick someone's ass at Rustoleum. No clear coat for anything on my droid now.
9) I set up a semi enclosed painting booth just outside my shop. I tacked up tarps to contain overspray and set up a table with an old lazy susan to put pieces on for spraying. That seems to have worked well, but if there's a breeze dust always gets in the finish. I tried to take the pieces into the shop after they started to flash off and then leave everything undisturbed until the coat set. The blue anodized says that it'll take 7 days for the coat to fully cure. It's been a day and a half now. If I had more patience, I'd leave them alone entirely for a week, but I'm too eager to see the dome come together.
10) Painting sucks.
I've been mounting some dome pieces today. Pictures and a report on that shortly.