eschlwc

a lot of you use touch-up paint on your bikes. myself, i'm building quite a collection of tiny jars of testors, cans of humbrol, and random others. i'm wondering if i should add another in a faux-chrome color to paint over chrome lugs that i had to sand down partially due to rust. they're kind of half chromed now. some spots are 'chromier' than others.

but they look kinda cool with the patina, so maybe i should just add a light coat of clear over them.

or should i attempt to mimic the once beautiful mirror-like chrome with some touch-up? is it even doable?

i see on ebay there are possibly a couple promising choices:

- mr hobby gūn chrome enamel (code 104)
- humbrol acrylic chrome/silver (code 191)
- humbrol enamel gloss chrome (code 191)

any luck in painting chrome lugs chrome? ...er, half-chromed lugs, that is.

Velognome 

Even without seeing it.....I say leave it be, original is always better then mucked, with IMO

eschlwc

^ that's what i'm thinking too.

sometimes i need to post an idea just to work it out in my own head.

it's really just the fork crown anyway. the head tube lugs looks pretty good.

randyjawa 

fogedabboudit!

Ed.

Next time:
1. Soak in Evapo-rust
2. When no rust present wash in hot soapy water and rinse thoroughly
3. Set aside to dry (or actively dry with hairdryer)
4. Apply clear lacquer and wax

rhm

My Allegro has fair chrome on the lugs, poor chrome on the fork crown, and not much more than rusty traces of chrome on the fork ends ("socks").



I elected to do nothing to the lugs and crown, just scrubbed the rust off, waxed, and let them be.

I did not feel that was an option with the fork ends. Rust is a serious issue, and bikes get wet. I sanded the surface as smooth as possible, sprayed on a sandable primer, and wet sanded that as smooth as possible. Then I sprayed on a chrome spray paint I had. It looks somewhat like aluminum; nothing like chrome. I'm not thrilled, but I thought it was a decent solution for now.

jimmuller 

I understand that was a common style theme on Belgian bikes:

eschlwc

i left the patina and gave them a clear lacquer finish.

DiegoFrogs

The chrome on the forklegs on my Carlton was much worse than the lugs, crown or stays. Most of it came off with the rust when I polished it. I had some silver nail polish sitting around that I use as a touch up on a silver bike, so I painted it with the brush. It's clear that it's not chrome, but it's better than the raw steel. I've been keeping an eye on e-bay for a fork with better chrome for when I eventually get the frame refinished/modified.

kunsunoke 

Full disclosure - I used to intern in a plating shop, and I spent several years supporting lines of aluminum pigments.

IMO - the only way to fix chrome is to completely strip and re-chrome. Steps in the process are as follows:

1) Chemical stripping of the old finish (mainly paint) + multiple rinse steps
2) Cleaning with caustic soap (pH is usually about 14) + multiple water rinses
3) Electro-cleaning with caustic soap (pH 14; current floats off the crusty stuff) + multiple water rinses
4) Acid stripping (50% muriatic or sulphuric - pH = 1; gets rid of the rust and old chrome) + multiple water rinses
5) Optional - cyanide copper strike (puts down the initial copper layer and cleans the steel) + multiple water rinses
6) Acid copper plating (puts a thicker coating of copper down as a base for the nickel) + multiple water rinses
7) Nickel chloride/Nickel sulfate plating (2-3 layers) + multiple water rinses
8) Trivalent chromium or (preferably) hexavalent chromium + multiple water rinses
9) final surface treatments (clear-coat, etc.)

If it sounds like a pain in the ass, it's because it is a pain in the ass. One fingerprint in the wrong place and all previous steps become irrelevant and the part has to go through everything all over again. It's expensive as well, and the chemicals tend to be pretty toxic.

Re-plating will necessarily destroy all finish components - and all patina that has been acquired over the years.

On the chrome replacement paints - if it looks like aluminum, it's because you are using aluminum. That's what the pigments are - flaked aluminum from conventional ball/media milling or from the newer vacuum metallization processes (e.g. vacuum metal coating of plastic film, with scabbing of the aluminum from the film in a solvent tank).

Achieving a good appearance from aluminum paint is a balancing act. You can make it look pretty and chrome-like if you load a crap-ton of pigment into the paint resin system, but then you have to worry about adhesion. The adhesion problem can be solved through use of non-leafing pigments, but then you need to load even more pigment into the paint, or use really expensive lenticular aluminum pigments - usually both.

Surface preparation is several steps more important than for normal paint. Any surface flaws become brutally obvious on a chrome-replacement paint. The most chrome-looking aluminum paints (vac-metal) are by far the most difficult to get good results from - and most of them aren't recommended for exterior or high-stress applications.

In other words -

Save the chrome if you can through oxalic acid cleaning, clear-coating, waxing, etc.

If you can't save the chrome, and the bike is a collectible item (ex. old l'eroica era Italian, Brit, French, etc) - clean it and seal it the best you can without messing up the patina.

If the bike is not as collectible, feel free to media-blast and powder-coat.