What are the causes of chrome pitting? My 72 CS has many items that the chrome is pitting on. Like power window switches, dome light escutcheons, door handles, radio *****, seat belt clasps. Bumpers are ok as are outside door handles. Is it mainly age or could it be that the car was once a flood car or spent much of its time in a very humid climate? Just curious. Also can the pitting be polished or buffed out. THOUGHTS anyone?

 

Its could be age, moisture, corrosion, salt air, all the above, etc... Wax is the only real prevention and sometimes it doesn't work depending on the environment. 0000 steel wool and soapy water will smooth it out, rinse well, then some carnauba wax for heavily chrome plated items.

 

Most likely lived in a humid environment. In particular, if it resided near a salt water body such as where I reside along the Atlantic Ocean, it's a constant maintenance task. My preferred compound is Collinite:

https://www.collinite.com/marine-wax/metal-wax/

 

If you are talking about pitting in pot metal that is chrome plated, the problem is the crappy zinc used as the base metal. There's nothing you can really do about it. Even NOS parts kept in the box in a controlled environment will pit.

 

There are three causes, which must all be present:

• A corrodable base metal.
• Porosity of the plating metal(s).
• Moisture or humidity and some form of mild acid or salt--sometimes that comes in with just dust or fingerprints on the surface.

Chrome is a porous plating metal. Copper is non-porous and seals the base metal. The best chrome plating has a heavy copper under-layer that is polished to get the next layers to sparkle. Then comes nickel and chrome layers.

Bumpers usually have copper plating over the steel, although sometimes it is too thin to do a perfect job.

For pot metal parts, that copper plate step is often skipped, which makes the parts very susceptible to pitting-type corrosion.

 

This....
It's mostly the crappy zinc that want's to corrode(.oxidize) under the chrome.... Tedd