TromboneAl

How should I deal with corrosion like this on the forks of my 1990 Bottecchia?

RickAccused

How deep is the corrosion? Has it pitted the metal itself or is it merely surface corrosion?

jsmithepa

Looks like surface pits to me (we hope).

Just like car, I'd use a paint cleaner (mild abrasive), and if closer inspection reveals no more blemish (surface only), then proceeed to re-wax. Some elbow grease required so don't even think spray-on and poof!

I personally use Meguiar's Paint Cleaner (any auto store).

markjenn

Look like it might be pitting in the protective clear coat to me. If so, I'd just leave it alone, but if you really wanted to fix it, you'd need to strip it and either reapply or keep it polished. In any event, it's not structurally serious.

- Mark

DannoXYZ 

If that's chrome, use TurtleWax ChromePolish. It has a mild-abrasive that'll remove the corrosion and polish up the metal. For a gentler process, use an ammonia-based chemical polish like Simichrome.

BCRider

It's hard to tell from the lighting but are they black painted or are they chromed? Camera settings along with the reflections can often disguise chrome surfaces.

The treatment for chrome and paint are similar but use different products. They've covered a trick for paint.

But if they are chromed then some chrome polish to clean them up as best you can and then a good cleaning and follow it with a good protective car wax.

Chrome, and a lot of paints for that matter, are quite pourous on a microscopic scale. Any paint, even the hardy clear over color combos, should have the protection of a good car wax once or twice a year. Regular washings may remove the surface wax after a time or two but the wax that gets into the pores is a lot harder to wash away and will provide protection for a long time. Chrome is especially bad for this. And thats why it gets surface stains on it and when you clean it away it SEEMS fine. But once it starts it's hard to keep the rust from coming back through these pores in the chrome.

J T CUNNINGHAM

NEVER use an abrasive on chrome.

Regards,
J T

BCRider

I'm sorry? The "abrasive" found in all chrome polishes is extremely fine and works to actually make the chrome even more shiney. The amount of metal it may remove in the process is only an issue after years of frequent use. And in the meantime it'll remove most or in some cases all of the corrosion blooming from below onto the outer surface.

DannoXYZ 

The abrasive in chrome-polish is very fine and chrome is very hard. TurtleWax chrome-polish works wonders on corroded chrome and adds protect wax layer as well. If you were to use chrome-polish on aluminium, you'll never get it shiny because it would be way too abrasive for that softer surface.

TromboneAl

Thanks for the tips.

Yes, it is chrome and the pits are not deep.

Protective clear coat? Is that some kind of lacquer that's applied over the chrome?

I had buffed with aluminum foil -- that was recommended at a bike shop, and that improved things a bit. Is that a weird thing to do?

I'll try some paint cleaner. My main objective is to keep them from getting worse.

I've noticed that the pits are clearly restricted to the leading edge of the fork. I wonder if they came originally from driving with the bike on the roof of the car??

markjenn

From your 2nd shot/left edge, it appears to me that there is some kind of plastic film or coating on the part, but if you're polishing on it, it's probably an allusion. Clear coating with a lacquer or plastic film is common on polished parts to help them maintain their appearance. Getting the clear coat off is typically pretty difficult requiring some kind of stripper and work. I doubt it is chromed. Chrome is for steel parts, not alum.

Yes, it does appear that the abrasion has something to do with the leading edge, although I'd be surprised you'd get many rocks up on the roof rack. Getting rock chips while riding would seem more likely.

Again, I don't think it is serious, so for this cosmetic issue, use a polish of your choice to clean it up. The only thing I'd advise against is using steel wool on an alum part as it leaves small pieces of steel in the alum which encourages more corrosion.

- Mark

jsmithepa

That's an affirm. They sell booties, or have the women in the house make one.

If it's indeed pitted clearcoat over chrome, then the option would be to remove damaged clearcoat, then re-apply (repaint).

J T CUNNINGHAM

"I'm sorry? The "abrasive" found in all chrome polishes is extremely fine and works to actually make the chrome even more shiney." QUOTE.


Just how thick do you think chrome plating is?

Try 5 microns!

More plating has been ruined by abrasive "polish", than I care to think about.

What you think is "chrome", after it has been abraded away, is the nickel plating,

and it will tarnish and must be polished again. The chrome finish gives the nickel

a silvery or "chrome-like", appearance so that it need not be polished all the time.

The above is the reason during the '20s, they started to chrome the auto trim -

no need to polish it every saturday!


Regards,
J T


PS. One of my former tenants was a plater; he allowed me to do my stuff as well.

(Been there; done that.)

BCRider

Granted JT. But it's not like we're out there polishing the chrome every day or every weekend. And in this case he's got issues with that fork that in balance are going to be best dealt with by using some Simichrome or the Turtle wax stuff to get the damage down a little and smoothen it out as much as practical.

Outside of the realm of someone with an obessive compulsive order it's highly unlikely that anyone is going to polish off the chrome. As already mentioned it's pretty tough metal even if it is only that thick. Besides, if you know a plater then you already know that the chrome doesn't come out of the vat already mirror finished. They use lots of buffing wheels with more aggresive compounds than the super fine stuff found in the polishes. So the chrome has already been through the wringer.

Did he suggest anything more suitable for cleaning up the chrome? It's always nice to hear about options from someone that's actually in the field.

Trombone Al, if that bike spent much time on a roof rack in the "wrong" part of the country that may well explain the almost sandblasted look I see in the second picture. I can't help but wonder what the car looked like after the same amount of exposure.

If the bike really means a lot to you it may be an option to get the forks re-chromed.

J T CUNNINGHAM

"chrome doesn't come out of the vat already mirror finished." QUOTE.


Yes it does, it is the "finish". eg the "iceing on the cake".


"They use lots of buffing wheels with more aggresive compounds than the super fine stuff found in the polishes. So the chrome has already been through the wringer." QUOTE.


The buffing takes place:

1) Parent metal.
2) Copper strike, and between any subsequent layers.
3) Nickel strike, and any subsequent layers.
4) Chrome. this is NOT POLISHED


"Did he suggest anything more suitable for cleaning up the chrome? It's always nice to hear about options from someone that's actually in the field." QUOTE.

Cleaning:

1) A solvent, such as water with a detergent. (for dirt)
2) "Neverdull". (as mentioned elsewhere in these postings; may be others but NO ABRASIVES!)
3) Wax, oil, or other coatings to protect the finish. ("chrome plating", is porus.)


Regards,
J T

awunder

Sing to it.






Sorry, I know that's not helpful, but I couldn't help myself when I saw that subject.

BCRider

Well, your description is sort of reminding me that the guy I talked with was more into industrial hard chroming. Hydraulic cylinders and the like. They also did some stuff that had to be polished but wear as well. A different process I gather.