Cleaning corrosion from polished cast iron parts

I’ve got a few finished castings that have been mirror finished and now show traces of corrosion. The light stuff is coming off with autosol and a jay cloth.

What’s best for the heavier stuff? Steel wool?

Try garraflex blocks in different grades.

Scotchbrite pads from your local automotive paint supplier

You'll need to protect the exposed metal "instantly" with a film of oil or something, cast iron is very prone to flash rust

Years ago I used a cleaning solution from ArcEuroTrade. Wipe it on, leave it a bit and wash of with water.

The corrosion often creates areas that have oxidised and that is effectively metal removed. Unless you take all the surface area down to the minimum of the depth of the corrosion, it will still be there. Garraflex or the rubberised abrasives are good or non flat shapes. On a flat surface, you will need another flat surface to repair it with. If you just want to shine the surface only and are not concerned with it's flatness, using Autosol , but thinned with turps or a very light oil, like plain unscented baby oil, and using soft material like a lens cloth, will restore the finish. But it takes time. Paper towels and even synthetic clothes material will creates scratch marks. Water will make cast iron rust in humid conditions within a few minutes. The other option is to use an oil based diamond polishing compound and soft balsa wood. Using the makers of the diamond thinning agent or baby oil works great too. The balsa will absorb the diamond and then behave like a lap. Lapidary diamond is water based, so I avoid them for cast iron work and other surfaces that corrode very easily. Balsa wood and Autosol also works very well, and you can see and control the area you are polishing. I get a small pack of mixed sizes of balsa wood from the hobby shop and it's about 4 inches to 6 inches long with varying shapes etc. Usually something in there is about right for the job. Keep each piece with the abbrasive type. I don't mix the abbrasive grades.

Edited By old mart on 11/03/2022 18:20:27

Edited By old mart on 11/03/2022 18:21:53

This stuff is good :- Belgom Chromes

I've used this and the Belgom Alu for years on my motorcycles.