I've got a 75 Supercourse that I'm restoring as a winter project. After having the frame powdercoated, I decided to paint the lugs a different color, but after masking and priming them, they just wont turn out right.
Kind of tough to explain, but the paint won't settle evenly ... it looks course, flat, or almost speckled, instead of a smooth gloss which is what I'm looking for. Almost like there's a lot of dust under the paint (although I made sure to clean the lugs before painting.) I'm using spray-can hobby paint (gloss black enamel), which I've used on other applications before but never got this kind of result. After it came out crappy the 1st time I sanded, re-masked, re-painted, and it still looks bad. Any ideas before I go through all this work a third time? Thanks much.
Gazelle Champ Mondial, Nishiki Comp II, Moto Grand Record, Peugeot UO-10, Koga-Miyata SS
When I painted my Trek 400 I used rattle can charcoal metallic. Not sure if it's the same situation but in certain spots the paint seemed more like the texture of a pile of arts&crafts glitter sprinkled over glue (if you remember that project). I think some of the problem was the funky angle I had to turn the can to get at places like the BB shell cluster. Someone also told me that with metallics you should heat the can gently in sub-boiling warm water and then shake the hell out of it for a couple minutes before you spray.
Powder coat is basically a thermoplastic, I believe. Could be a reaction with the solvent in the enamel you're using, or maybe you didn't scuff up the area to be painted enough. I'm waiting for Dr. D to weigh in; he'll know fer shure.
What primer did you use over the powdercoat?
And, what paint are you now using?
Was the can VERY adequately shaken?
And is the temperature of both the frame and the room where you are spraying warm enough - and staying warm after painting?
Have you tested the paint on something else, placed in the exact same conditions recently?
What is the humidity in your painting environment?
Does not sound like an issue with the powdercoat at all. You should even be able to spray paint over a plastic soda bottle or a chrome bumper if the preperation is correct, the paint is appropriate for the application, and instructions for the paint are all followed ... Could be just a bad paint can or the primer you had selected is incompatible with the paint you are using.
Adequate and consistent temperature makes a big difference. Don't expect things to work right if you are leaving the bike in an unheated garage in December in Minnesota. 70 degree room temperature is usually fine. And, typical household humidity range is also usually good too. Just be sure to read the specific instructions in tiny print on the can. And, don't leave the frame in front of a furnace blowing out dust onto the project or heating everything unevenly.
Winter sucks. I really will not be able to paint anything for several months.
Any ideas before I go through all this work a third time? Thanks much.
First let me say that when I paint over a powdercoat base, I use top quality (=expensive) automotive paints. These differ greatly from rattle can paints, and need different prep to work properly.
So, to address ChillGreans situation...which I agree, is hard to describe.
Might be that you didn't sand the primer before spraying the color.
You can also scuff with a fine grit ScotchBrite pad. Just enough to break the surface and give the color some tooth.
Might also be that you don't need primer to shoot black rattlecan paint over a powdercoat base.
In which case, you could rattlecan clear the whole frame, once you've done the lugs black.
And if you've redone them a time or two, that might be a good thing anyway.
Or just shoot the black, no primer, and call it good.
UNmasking is another area of interest...
Some say unmask while the paint is wet so that the wet edge "heals" itself a bit before hardening.
Others say wait until the paint is fully dry and the edge will be clean and sharp.
I've tried both ways.
Success & failures either way.
Having a fresh sharp #11 Xacto blade handy helps.
The thing to look out for is, the paint coming off with the tape and pulling off pieces of the paint you want to keep. So you use the #11 to surgically separate the paint at the edge of the tape.
Might also be that you need to spray a thicker, wetter coat of paint.
The first coat or two can be light, but to get that wet glosss look, you need a medium heavy coat so it flows out all smooth & shiny.
Might be that someone nearby shot some WD40 and some particles blew onto your frame between coats.
That would cause the notorious fish-eye effect. Lots of little fisheye dots in the paint.
Without detailed close-up pictures of the problem, I can only guess though.
My money is on..."Thicker, wetter, final coat of paint".
But check with the powdercoater and see if he/she has any insight on rattle can compatabilty with their powdercoating.
A final thought...you could probably get away with doing the lugs witha nice 8-10 dollar paintbrush from the art store. One-Shot Sign Lettering Enamel is one of the best paints. (Better than Testors model paint)
If you have gone to all the trouble to mask, it should be pretty easy to get the black on with the paitbrush. Same trick applies, try to get all the paint on the lug quickly enough that all the paint is wet at the same time. This allows for flow-out and produces that nice shiny gloss.
This may be one of those times to UNmask while still wet-ish.
Good luck & let us know the final result...ie; PICTURES! Please.
Based on what was said here, and what others have told me today, I think it's because the room I was painting in was too cold (about 60).
Not sure if its the powdercoat because I sprayed onto a powder coat before w/o problems. (different frame, different color, same powdercoat painter, same rattlecan paint on my part.) That one came out fine. Only difference I can think of is that the 1st was done in sept, when the weather was warmer than where I'm working now.
Think I need to re-sand and start over, or should I try spraying over the bad lugs once I get the frame and paint into a warmer area?
And I promise for pics when this is done! The lugs are nice capella lugs (which I'm painting black) and the powdercoat is a metallic sparkle green