Vintage watches crystal condensation

[RyanGreerMcGilloway]

Hi all I have a ANCRE divers watch here and I’ve noticed that sometimes the face condensates and I wonder why. The back cannot be any tighter, the crystal is tension ring fitted and I’ve stuck an o ring I had lying around in the crown.

 

can somebody please advise. I have this issues with a few other watches, another is a 90s seiko 7002.  

[jdm]

There was humidity at the time it has been cased. Open it and dry the case and crystal well with an hairdryer. After closing with new gaskets touched by silicone grease on them, test it warming the whole and placing two drops on cold water on the crystal. That won't however replace a proper pressure test.

[yankeedog]

I have noticed this whenever I clean a case with hot soapy water. If it is not absolutely and completely dry upon reassembly this will happen.It doesn't take very much moisture at all.

[RyanGreerMcGilloway]

Okay so its not a case of moisture / water getting in.

 

Its simply just a case of moisture already in there and heat creating condensation? Once i remove all moisture within, it should happen again?

[nickelsilver]

We were taught in school that even in a 99% humid environment, there isn't enough air in a sealed case to actually condense. In recent years I've seen it proven, on paper at least,  that some watches in some cases can show some (like a tiny bit) of condensation. But basically, if there is clearly visible condensation there has been an influx of water (or improperly dried case after cleaning as above).

[Tmuir]

Depends on whether the case is water tight.

Do you have a pressure testing machine?

The Swiss ones are hideously expensive, but the Chinese ones are quite reasonably price and actually good quality.

 

[jdm]

2 hours ago, nickelsilver said:

We were taught in school that even in a 99% humid environment, there isn't enough air in a sealed case to actually condense.

Could be. What can also happen is I that one has washed casing parts but didn't dry them well enough before re-assembly.

[Watchtime]

Crown/tube can be the cause of water getting in, open it and dry it with a hairdryer as said.

If you have it on more of your watches, maybe you are storing them in a humid surroundings?