Newbie Question about Tudor Sub Hands

[jonthefisher]

This is a newbie question but I was looking through the "Vintage Tudor Submariners Show Em" thread and am wondering why some Subs have hands that look like they have been rubbed with sandpaper or something very rough. Was this due to corrosion from being around saltwater, from poor attempts at servicing in the past, or from something else?

I have a few Prince Oysterdates from the 1960s and 1970s and none of them have hands like this, one has very light freckling when you look at it under magnification but that is it.

Two examples from that thread are attached.