Rainbow83

Hello folks. I have an interesting phenomenon that I'm hoping someone here has an explanation for. I have an old Motobécane, from about 1979, and it's got this funny thing where, in the presence of moisture, the paint seems to fade from black to a creamy sort of color, although only in some spots, and then after some time, the bike looks normal again. I'm pretty careful with keeping this bike stored properly, but I've noticed this twice now. Once a few years ago when I left it on a porch on a misty night, and today, when after a big rain storm, I noticed the garage had some leaks, although this bike doesn't actually seem to have been being directly dripped on. What could be going on here? Why is my paint not just staying black, and why does it seem to be patchy? Could it be that there's a cleacoat that's worn off the bike that prevented this? Is this something I should be concerned about? Any info is much appreciated.

JohnDThompson 

Have you tried a fine rubbing compound to remove the surface discoloration? Be gentle, you only want to remove the discolored layer. That should exose a fresh paint surface, which you can then protect with wax.

Kontact 

I dont know if I'd want to mess with such old paint. Maybe get it really dry and black, then test wax the underside and see how it looks wet.

dedhed

https://www.meguiars.com/automotive/...07-7-oz-liquid

Rainbow83

Wax is a good idea. I'll give that a try to protect it. That being said, has anyone seen anything like this before or know what's happening?

dedhed

It's likely a clear coat issue rather than base coat

greatscott

Without being there and looking at it closely, but first thing that is obvious is you have a high degree of paint fade, so try the Meguiar product a poster mentioned earlier, but like another poster said try it on the bottom side and see what it does. Bicycle paint is not as thick as car paint, so you have to be careful you don't over do the buffing.

The other thing I noticed, and again since I'm not there I can't tell if this is the case or not, but it appears there is rusting going on under the paint, if that's true no wax is going to help that, and if it's under the paint, I dread to see what the inside of the tubeset looks like. I suggest you remove the seat post and with a flashlight look down inside the tubing all the way to the bottom bracket and see if there is rusty crud anywhere inside, if there is the frame is toast. If you see decent metal on the seat tube itself, but there appears to be rust on the bottom bracket area, then you will have to remove the bottom bracket and get a closer look at the extent of the damage. If by some chance you have one of those small probe cameras on a long skinny flex arm then by all means use it to see what the tube sections look like.

Rainbow83

Hmm, it didn't look too bad when I redid the BB last winter, but I'll bust out the borescope and have a look at it again, at least for curiosity if not to find any rust. Where does it look like it's rusted under the paint? Looking at it in person I'm not sure I'd draw that conclusion, but I'm also not sure I'd know what signs to look for.

oldbobcat

Some pigments just go "chalky" when they get old and weathered, for example, 40 year-old red Corvettes left out in the sun. Buff it out with a nice auto wax.

rccardr 

Could be wax. Same thing happens to one of my bikes when it gets wet, goes away when it dries.
I think it was the wax I used on it when restoring.

zandoval 

This is pretty common with furniture that uses a tradition organic varnish instead of one that is Poly or Ester based. That kind of finish deserves really good waxing with light polishing. Don't use any solvents on this type of finish...

Of course you knew this...

JoeTBM 

Exactly what I was thinking,, especially on the down tube at the head tube, almost look like it is rusted through.

Mr. 66

I think the first thing I would try is wiping down with motor oil, then wax. That can do wonders for oxidized paint, but if the clear is releasing from the base that's another story. If that were the case I would probably do a light to medium rubbing compound, or maybe even a very fine wet sanding before the compound.

Iride01 

Might be a wax build up if you or a previous owner was waxing it. Or lets just face it, 44 years on a paint job for something seeing regular use is pretty good.

If everything else is in decent shape, you might use some rubbing compound on it everywhere, especially where the cloudiness occurs. Then have it clear coated.

Don't get too crazy with it though, if you just lightly go over it and then clear coat it, you'll be preserving some of the old character and patina that it currently has.

KerryIrons

Quite possible that a bike of that age didn't have a clear coat. It looks like the frame decals are on top of the paint. Most likely what it happening is that there is a layer/film of oxidized paint on the surface that absorbs water and then appears to change/fade. That bike needs a paint job but in the absence of that, a good coat of car wax, perhaps preceded by a rub-out would probably reduce this issue.

Mad Honk 

I am in favor of the Meguiars product mentioned earlier. When I worked at a GM dealership we used the products almost exclusively for body shop paint and repair work. Smiles, MH

Rainbow83

Thanks for the advice folks. I'm currently away from the bike for a while, but when I'm back there, I'll give it a go with some wax and maybe try to buff it a bit as well.

Iride01 

Adding more wax to the problematic and old wax that appears to be on it already seems like only a temporary fix at best.

I haven't put wax on anything since before the turn of the century. And all the things that I have that I previously would have waxed are none the worse for not having ever having any wax put on them. The things I did wax long ago that I still have don't look so great and some show some cloudiness like your bike does.

Sure would like to have back all that time I spent on weekends waxing my car as a teen!