Classtime 

I got my abused PX-10 down to bare metal and have begun the painting process. I'm painting the fork first so if I screw it up, there is not much work involved to start over. The first attempt was less than satisfactory. I had sanded well with 320 wet/dry paper, cleaned with simple green an then mineral spirits and applied a coat of Rustoleum Rusty Metal Primer with a "nice" brush. After drying for two days, a light fingernail scrape took the paint off. After a week, the same result. So....I stripped it, did some more research, and I almost used Duplicolor Self Etching Primer. Not wanting to mix products, re-researched and prepared for my second attempt: coarse emery cloth, simple green, and then MURIATIC ACID 14% which I had in the shed for but never use it in the spa. I put on latex gloves, poured about 2 ounces in a small bowl, and with a green scrubber, lightly scrubbed the upper fork blades and crown. This gave the chrome a brass tinge and took away the shine. After about 4-5 minutes I hosed off the fork, dried it, and cleaned it with a product called Prep All. After it dried I painted again. Wow. What a difference. The chrome really held onto the paint as I brushed it on compared to the paint slipping on it the first time. After less than 24 hours, my finger nail scrapes the surface of the paint but does not lift it off the chrome. This is one thin coat. When I get to frame, I plan to prep it the same way.

verktyg 

One suggestion...

You may run into paint compatibility problems if you apply a lacquer type top coat that contains solvents like xylene, toluene or similar products over top of a petroleum or water based primer.

Same thing with clear coat over top coat.

Best to apply the primer to a small surface, let dry then apply the top coat and let it dry. Finally the clear coat.

verktyg

Chas.

Kitsap

Remember that paint bonds mechanically.... Sanding with 320 grit sounds too fine. I'd recommend 80 or 120 grit. Further, degreasing with Simple Green should be plenty; if something more is needed (degreasing wise) then I'd use acetone not mineral spirits. Ideally it would be best to abrasive blast to remove all the crome plate down to the nickel or steel.

Salamandrine 

For a slightly safer method of acid etch, Barkeeper's Friend does a pretty good job. It's mostly oxalic acid.

I recently repainted a 1/2 chromed frame, and used this sequence: Strip and sand. Quick wipe with naphtha, clean with acetone, rub down with Barkeeper's Friend in warm water with a drop of detergent - using fine scotchbrite for a sponge. Let dry.

Primer, paint, clear.

Personally I think 320 is plenty fine. While I'm not a materials scientist, I'm pretty sure paint isn't supposed to rely on mechanical bonding. The main point of the abrasion is to remove surface tension.

Tandem Tom

Just finished my first frame today. I sandblasted it then sanded and sprayed it with epoxy primer. Base coated, applied decals and then sprayed the clear coat. The fork was chrome and it worked well. The frame was my 1983 Schwinn Super le Tour which is my 650b winter project. I am getting ready to do my 1984 Miyata 610 as soon as the decals arrive. I plan to post pics of the process when done.

Classtime 

Thanks for the suggestions. This is a budget diy project. No blasting or spaying. I was trying to get by with elbow grease and three 1/2 pints of Rustoleum but most every hot rod and motor bike forum post recommended using one of the wax an grease remover paint prep products so I sprung for that (and latex gloves).

Salamandrine 

I pocketed the cash I saved by using home brewed etch and prep and spent it on Rustoleum Professional spray cans.

You will have much more wet sanding to do if you are brushing on.

FWIW the standard old timers trick is to thin oil enamel with genuine turpentine, not paint thinner. This will make brushed on oil enamel flow out very nicely and glass smooth, but it also increases the dry time by quite a lot.

Cougrrcj

Waaaaay back almost 30 years ago, I had painted some parts of my vintage Mercury Cougar with Rustoleum Rusty Metal Primer - that paint didn't cure completely in six months!! I had to strip it all off and start over, too! Never again!!!

lord_athlon

Shouldnt you wipe with Acetone before painting?

fietsbob

factories only polish the metal on a chromed frame/fork, that will be left unpainted

the rest is sandblast finish under the CP, that helps paint stick too .. "tooth"

Classtime 

I'd say half the chrome under the original factory paint was polished and the rest, while not smooth, was very slick and shiny. After using course emery paper, the shine remained and the lumpiness of the upper blades and fork crown prevented the abrasive from reaching the little nooks and crannies.

Centaurious

One tip to get a really clean line at the Paint/Chrome transition is to use pinstripe first and then tape to the pinstripe. It keeps the paint from migrating under the tape.

This can be done from Paint to Paint but you really need to let the base paint cure well or it might lift when you remove the pinstripe, it is not intended for removal like painter's tape.

Lascauxcaveman 

I'll respectfully disagree with that - 320 grit should be plenty rough. But chrome is plenty tough, you need the right kind of sandpaper to rough it up. I've had good results wet sanding chrome with whatever the standard wet-dry paper is they sell at my local hardware store. The primer never fails to hold onto the metal (chrome or otherwise). But I'm spraying from rattlecans, not brushing it on, unless I'm painting something made from wood.

markk900

Just for reference, I used 220 dry as the "material remover" paper, got things as nice as I could then first coat of primer. Used a combo of 220 and 400 to get the primer smooth (it shows the places you didn't prep well very nicely), then a second coat of primer. A light sanding with 220, then 400, then colour coat (spray bomb rustoleum), then let it cure for at least a week if not more (ignore the can - it lies! You cannot recoat in 48 hours- DAMHIK). Wet sand with 400, then another colour coat. Repeat as you fix your mistakes. Last sand was 600 wet and a final colour coat. Turned out much better than I expected.

Rustoleum is pretty soft for a long time so be careful after you are done (again, DAMHIK)