Removing spray paint? (But leaving the original...)
 

I just picked up a frameset that was listed on CL as a 73 Raleigh Gran Prix, but I think might actually a Gran Sport, based on chromed stays and the fact that it's surprisingly light.

Unfortunately it's been rattlecanned black, right over the chrome as well. I know any basic paint stipper would leave the chrome, but is there any way to preserve the original paint? I'm imagining a chemical that interacts with the spray paint but not the different chemical make-up of the original paint.

Grasping at straws, I know! I was taught it never hurts to ask...

You have to go through a hierarchy of solvents. Put a little solvent on a clean paper towel, rub your frame a bit, and see if your paper towel is still white. Do this outside. If it's turning the color of your frame, your solvent is working. You want to find the most innocuous one that will do the job. Start with stuff you have around the house. Denatured alcohol is about the most innocuous but probably won't do anything. Naphtha is more likely to work, but already unpleasant to work with. As you get to nastier stuff, the odds are you'll find something that works... but it might be pretty unpleasant to work with.

If a poorly done rattle can job, I actually had good luck scraping most of the paint off of parts of a frame. In my case, I exposed the decals, and the 531 stickers... :)

I forget specifically what I used to avoid scraping through the factory paint, but I seem to recall stiff plastic, perhaps the back side of a plastic knife...

That's not a bad idea which I hadn't considered, I've got a cheap plastic putty knife that might work especially if it wasn't prepped properly... Otherwise I'll start with the ranger chemicals as RHM suggested, thanks both!

acetone can take off spray paint and not the original.. as long as the cleacoat is still intact under the spray. put some on a towel and the rattle can will wipe right off. its about as non caustic as will actually do anything. you know, its nail polish remover and its about 5 dollars for a big can at most hardware stores.

I did that with my pinarello... unfortunately what was underneath was not pretty either. (someone had half stripped it down before rattle canning)

I wonder if mineral spirits would work. I've been thinking the about doing the same to a frame that was very badly primed (it looks like directly on top of the old paint/decals).

Acetone works and I've used lacquer thinner. But be carefule not to rub hard. Also take care around where decals might be. If they are over the clear you can wipe the color off the decals.

What's Under There
 

Do not use acetone or lacquer thinner they like stripper will take the original paint. I have had limited success using California paint thinner which is much weaker than your run of the mill old school paint thinner. They reformulated it about ten years ago to be kinder to the environment but like most things the Government sticks their noses into it ruined it. So that and a half used dish sponge with one scratchy side dipped in the thinner and gently rubbed peels it off rather nicely. Around tight spot's like the bottom bracket and where two or more tubes meet you have to take more care and an old tooth brush comes in handy here. This is a beater turned $5 bike into $50 bike.

acetone just took the spray and left the undercoat of original intact in my case. but i'd certainly do a test spot first before dousing it down.

Keep the advice coming! I probably won't get to work on it till Saturday, but I was looking closer at the frame just now and realized the fork has a Reynolds 531 sticker, could just make out the numbers through the paint, but it looks like all the seat tube decals were removed before paint, there is something that wraps all the way around the tip of the bottom tube still but I can't make any writing out yet...

I would start with mineral spirits. I have had good luck with the stuff.

Another vote for acetone. I started on the endeavor on a bike I had, but quickly realized why it had been rattle canned.

I had a few minutes so I ran out to the garage and found some 70% isopropyl alcohol, it's working great!

Having trouble uploading pics...

I've had decent luck with a light duty scotch brite and water. The kitchen kind with soap built in. When it is done you will need to rubbing compound it to get gloss back, but it worked quite well on a couple-layered Giant I had. Lacquer thinner is a no-no on old finishes as many of them are succeptible to it. Modern finishes, particularly urethane are a lot harder to damage by it. Benzene/gasoline can work as well. I used to like using aviation gas(different from car gas), but that evaporates a lot cleaner than car gas.