I haven't written about it yet, but we've been practicing case refinishing for our entire program so far. We're almost ready to service a complete case.
I'll cover all of the steps involved in the refinishing process later, but for now let's focus on the lugs. Those are the tips of the case that attach to the strap or bracelet, and they're devilishly difficult to do properly. Since the metal is so thin, any mistakes are immediately amplified.
All of the following photos are of imperfect practice pieces. I'm not quite ready for prime time, but they should give you an idea of what to look for!
The most important thing to remember when doing any refinishing work is that you should never, never change the geometry of a case, even if that means letting some damage go unfixed.
With that out of the way, let's look at what you should do.
Many watches have a line finish on the tops of the lugs, which is done with an abrasive block or wheel. Since the finish is a gentle grinding operation, it's important to do as little as absolutely possible—every second means more metal is removed from the case.
If the finish is angled, all four angles should be equal. Vintage Rolexes have a 45° angle, while modern ones are a straight finish. The important thing is to maintain the original angle.
Many watches also have polished sides. If so, the line finish and polish should meet with a precise, laser sharp edge.
The brushed finish will naturally carry over onto the polish, so proper lustering (a mirror polish after the actual polishing step) is required to form the border. You can see a spot of carry-over about 2/3 up the border in the above photo.
The polished and lustered surfaces should be perfectly shiny and flawless mirrors. Poorly-maintained polishing wheels will leave streaks on the mirrored surfaces.
Finally, the lug tips (if the case has them) should be polished and free of line finish carry-over.
All of these steps are hard, and putting them together is even harder. Stay tuned for the next steps!
Watchmaking student at the Lititz Watch Technicum, formerly a radio and TV newswriter in Chicago.