Tmdhawk, and others,
I'd like to relate to you my high-temperature painting experience from this past week. I painted several parts using Duplicolor Engine Paint (marked with Ceramic). The immediate results may interest you.
First off here's what I painted and how - and I'm going to go into some detail on this. First, all of the parts were sanded beginning with 150 grit and moving up to 400 grit and polished (black, then red, then white Caswell compounds). I painted a front and rear hub, Alternator Cover, Sprocket Cover, and a number of small parts.
On the hubs, the center sections were not sanded, they were cleaned and hit hard with a drill-powered wire brush, the flanges were sanded and polished. After polishing the hubs were wiped down with Acetone to remove the residual wax from the compounds then scrubbed with dish soap and hot water and allowed to dry. The flanges were masked.
The covers received similar treatment, they were cleaned and then the recessed sections of each case (the word "HONDA" in the Alternator Cover and the numbers "1-2,3,4,5" on the sprocket cover) were roughly masked.
All parts were kept in the house over night as was the paint. I wanted all parts and paints at the same temperature the next morning. Next day I took the parts and paints to a friends heated shop (indoor temperature similar to my house). First I shot each part in Duplicolor Primer - two light coats followed by one heavier which I allowed to dry per the can instructions (about 10 minutes between coats). Then I shot my color, which was also applied in two light coats, one heavier, per the can directions. After the second color coat was dried I removed the masking and then shot 2 coats of Duplicolor clear.
Then I left the parts for 6 hours to dry in the heated shop. After the 6 hours I brought the parts home and set them several feet from our wood burner where they sat overnight and got very warm.
Next day I repolished the Alternator and Sprocket covers. All of the excess paint was removed but the paint stayed without any chipping in the recessed parts of the covers, making the inlays really stand out.
Then I laced the rear wheel. You poke and bang lots of parts together when you lace a wheel; I got no chipping with the rear wheel. Next I laced the front wheel. Everywhere a spoke touched the paint it chipped. Anywhere I sat the hub down it chipped. If I so much as looked at it cross-eyed it chipped. I pulled the spokes back out of it and set it aside to ponder the situation.
And that's where it is now, three or four days later. I just picked up the front hub and took a hard look at it. I notice one thing. First there are a hundred chips in it, not just one or two, and second that in every case the chip goes all the way to the bare aluminum. That tells me that it was the primer that didn't stick to the metal, not a problem of the color paint not adhering to the primer.
So ...
Normally, I believe, when you paint aluminum (which I have very little experience doing) you begin with a zinc-chromate primer. I think that will be what I try next. I'm not going to put that wheel back together if I think the center color might chip because you can't fix it without taking the wheel back apart and I do not want to have to do that anytime in the future.
