Restoring bikes with rusted chrome?

[uart]

Whether you're a serious restorer or just like cleaning up the occasional old bike to give it some new life, rusted up chrome has got to be one of the ugliest and most annoying things you encounter.

Short of getting something professionally re-chromed, what are your preferred methods of dealing with badly rusted chrome on bicycles and components?

[P!N20]

Aluminium foil and water.

[uart]

Aluminium foil and water.

Ok for lightly rusted chrome, where you want to preserve that chrome. On badly rusted chrome however, isn't that type of clean up just going to result in the rust coming back relatively soon?

What other options are there for cleaning and painting or sealing it against future corrosion somehow?

[10speedsemiracer]

On screws and clips etc, I use apple cider vinegar. Drop into an old water bottle, shake up, leave for a while, shake up, leave for a while etc. Rims (steel) and spokes I get into it with steel wool and wd40. Have also used Kero and steel wool on things like chrome car bumpers to good effect.

[Mozziediver]

+1 aluminium foil and water for chromed rims and big parts like bars.
Then Ranex (phosphoric acid preservative), rinse, wax. I use Renaissance wax, but Turtle wax is probably as good. If you want to stabilise the rust, Ranex seems well regarded.

For loose parts 3% citric acid and water, left overnight or longer.
Oxalic acid is widely used as a rust remover, but is toxic and aggressive - most mild acids like vinegar or CocaCola(TM) work. Citric acid doesn't smell, though, and is readily available.

I've used these two methods on a Twenty folder and other odd parts.
Hope this helps.

[uart]

Ok thanks guys.

What about passivating heavy rust on old chrome and then painting it? With non chromed tubes it's relatively easy to get back to bare metal, but with rusted chrome I really worry about how much rust is still lurking underneath. And chrome is too hard to fully remove.

Has anyone had much luck in cleaning badly rusted chrome and painting it to achieve long term protection?

[Clydesdale Scot]

Oxalic acid is widely used as a rust remover, but is toxic and aggressive -

if you eat sufficient quantities or fail to take basic precautions to prevent excessive exposure
https://www.cdc.gov/niosh/docs/81-123/pdfs/0474.pdf

but the same goes with Ranex
http://www.bondall.com/wp-content/uploa ... BUSTER.pdf

the concentration of oxalic acid used is very weak, leave it soak for a few days, brushing off the converted material them back into the bath.

For smaller items I use Evapo-rust. It is non-toxic
http://www.evapo-rust.com/info/EvapoRustMSDS.pdf

I have also used electrolyis.

It appears that aluminium foil works as an abrasive. It is harder than the rust but softer than the chrome. It is often suggested using it in combination with a weak acid (Coke) as the phosphoric acid is a rust converter.
But be aware that phosphoric acid is also lethal
https://pubchem.ncbi.nlm.nih.gov/compou ... nformation

If I was wanting to remove the chrome I would ask a metal plater a price on electro chemical strip to remove chrome and then a chemical bath to remove nickel and copper.
A lot of the cost of chroming is the labour to polish the metal. As you will not need that polishing, it may be cost effective to have a professional remove the chrome. You will then have a known base metal to repaint.

[QuangVuong]

The best way would be to send it to the chromers to strip the old chrome off. You won't run into issues of high/low spots.

I've recently repainted two frames which had dead chrome. Here is one of them.
IMG_2102 by Quang Vuong, on Flickr

This rust was quite heavy, all the way through the chrome and even into the steel underneath. What I decided to do was to sandblast it. I chose this method as I wanted to finish it relatively quickly, rather than possibly have delays at the chromers. The rust was blasted away leaving a lower pitted surface, whilst the good chrome stayed pretty intact.
IMG_7064 by Quang Vuong, on Flickr

Then I just went with an etch primer, then filler primer, then sanded it back to get a flat surface. Did I remove every spec of rust? Probably not, but I reckon the paint will last long enough. Only time will tell how well I prepped it.

[Thoglette]

Lots of old threads here and elsewhere. Weak acids (molasses, phosphoric etc) and gentle abrasion (al foil or bead blasting) are the consensus.