Watchmakers............a question.

JimInOz · Feb 14, 2022

Have you ever seen this effect?
Do you know what causes it?

I'm currently servicing a watch with a Valjoux 7750 and I've noticed a number of the parts have a "frosted" appearance.

The inside of the crystal also had a very hazy white deposit on it when received.

Parts were hand cleaned with a soft brush/pegwood and Elma cleaning solution, then through the watch cleaning machine using Elma LUF Pro cleaner and three rinses in Elma Suprol.

Even after that, there was still a frosty finish to some parts and these had to be polished and cleaned again.

Here is an example (ratchet wheel). Note that it only seems to be the exposed surfaces, the underside of the wheel was nice and clean.

ghce · Feb 14, 2022

No, never seen it in a watch but it reminds me of Teflon spray.

Archer · Feb 14, 2022

I've seen this before - hard to know what exactly it is, but some sort of residue from something that was used to clean the movement at some point would be my guess. There's a chance that something inside the case was off gassing also, but unless you see similar residue on hands and dial markers, that would be unlikely.

Usually can be cleaned off physically - I use a piece of watchmaker's tissue paper, lay the part on it, and use a leather buff stick to grip the part and polish it on the paper. Parts are cleaned again after that, just to be sure.

marpro · Feb 14, 2022

Out of curiosity and a slight offtop, as I'm facing this exact problem now - is the 7750 (old 17 jewels version) rotor bearing still available for purchase somewhere?
It is the one pression fitted into the rotor, contrary to the newer that is screwed in with a washer using a special tool.

Can't fint that part anywhere. Whoever I asked, they only had the newer screwed in version.

Archer · Feb 14, 2022

marpro
Out of curiosity and a slight offtop, as I'm facing this exact problem now - is the 7750 (old 17 jewels version) rotor bearing still available for purchase somewhere?
It is the one pression fitted into the rotor, contrary to the newer that is screwed in with a washer using a special tool.

Can't fint that part anywhere. Whoever I asked, they only had the newer screwed in version.

You mean like this...

That's really not pressed in. The rotor bearing in say an ETA 2824-2 is pressed in, so it can easily be pressed out, and a new bearing pressed in. The bearings in these are burnished in place, so the bearing is inserted and then a part of the rotor is burnished over to hold it in place. You can't just press one out and press another in.

Your best bet here is just to replace the entire rotor.

marpro · Feb 14, 2022

Archer
You mean like this...

That's really not pressed in. The rotor bearing in say an ETA 2824-2 is pressed in, so it can easily be pressed out, and a new bearing pressed in. The bearings in these are burnished in place, so the bearing is inserted and then a part of the rotor is burnished over to hold it in place. You can't just press one out and press another in.

Your best bet here is just to replace the entire rotor.

Exactly like that one.
Now that would explain why I can't find the part - it's irreplaceable.
Thanks a lot for the answer. This was driving me crazy.