Refinishing after rust removal

RedVitus · September 19, 2022

I worked through this refinishing issue and decided to post my solution for forum readers who may end up in this situation.

During a routine watch service, I noticed a little surface oxidation on a pocket watch spring. It wasn't a lot, so I tried removing with a glass fiber brush. That removed some of the rust, not all, so I decided to go further.

Then after some light work on a coarse diamond plate, the rust was gone, but it left a reflective, polished looked instead of the dull finish originally that all the other steel parts under the dial had. The two pictures below show how the spring looked after rust removal next to a part (yoke) with finish I was trying to match. It looked almost passable from one angle but from another (direct on top) not very close.

I hadn't come across the situation before. Typically when I refinish steel it is to mirror finish. Never tried to match a dull or grey finish.

First guess was that it would naturally dull over time and I shouldn't bother but after some thought I came to the opposite conclusion.

I did a test to see if I could dull the metal to at least get something with less luster. Having some experince removing rust from old tools with vinegar, I knew that it changes the appearance- usually darkening steel.

I decided to try it so placed the part in white vinegar. Perhaps a short soak would dull but not darken the metal? A few minutes gave the grey that I was looking for.

The after photo is below. Looks pretty darn close to my eyes.