I have a frame that has been powder coated black. wanted to put decals on it to break up the all blackness of it, but my test decals have been less than satisfactory. I priced some vinyl wrap arounds but the local sign shops want way too much for them. I know there are sources on this forum for decals, but this was kind of a spur of the moment thing. I'm wondering if its possible to paint a 9ish long white band around the down tube apply the decals and then clear coat over the top of it. Anyone ever attempted that, or should I just live with what I got? Last thought is if possible, whats the best prep for it?

yes. you can do it.

the only prep you probably have to do is to make sure surface is free of oils, etc. test some alcohol on an area (bottom bracket) to see if there are any adverse effects. acetone would do it too, but that may be too strong for powdercoat.

you can clearcoat over pretty much anything, so you should be good to go when you're done.

edit: on second thought, just clean the frame up with soap and water. disregard my alcohol/acetone suggestion. make sure you rinse it clean and use gloves so you don't get any oils on your frame before you paint.

I've got a couple frames that I would like to have powder coated but I've always wondered if the surface of a powder coated frame will be smooth enough for decals.

Yes u can paint over PC, the only thing you have to do is to sand slightly with 600 grit wet sand paper, mask then paint and clear coat.

As for the decals u mean water slide decals right??, well it depends a lot of the decal paper u are using to start with, to apply the decals u have to sand a tiny bit with like 2000 grit sand paper (thats how i do it ok? many other ways to do the same), clean really well with alcohol, put the decal in warm water with some soap in to, slide the thing in position, take bubbles out using a squeegee thingy, let it dry and then clear coat it with car paint clear or maybe u-pol #1 clearcoat that is car clear coat in a can, this wont get yellow with the time as hobby type of clear.

Yeah I'm talking about the water transfer decals.

OK yes u can paint that band u want around the tubes but i advice you to sand to etch the surface a little bit so the paint has something better to grab on, then clear over it. On the clear dont even dare to put crylon or anything similar because that could burn the powder coating clear and sure u dont want that. Use U-pol #1 is a spray and is safe to use over the PC job u have in there and wont get yellow because it has UV filters, cheap clear gets yellow after 6 months big time. The u-pol is like 15 bucks, too good for the quality and probalby you will be able to ride the bike next day with this stuff because dries to the touch in 15 to 30 mins. Krylon and other ones are just garbage.

As for the decals, just apply them after u paint, then clearcoat over it.

Sand slightly 2000 grit, paint the stuff u want, apply the decals, then clear. Then to finish you can sand the clear and polish (this one depends on you)