Originally Posted by
walkerwek1958
Unless you have the skills and capability to take the movement out of the watch this is a bad idea.
I use a cheap wet tester that goes up to 6 bar. I don’t like wet testers, they need using with care, but I can’t justify spending big money on the alternatives. These things are OK if the watch doesn’t leak, but if it does there are a few ways it can end badly and that’s why you need the capability to strip the watch down sharpish if things go pear- shaped.
Lets work through the logic: You don’t know whether the watch is watertight so you wish to test it. The watch is suspended in the airspace and pressurised to 6 bar. You leave the watch for a few minutes, then what do you do next?
Lets assume the watch isn’t sealing correctly, the pressure inside the case has equalised at 6 bar. If you drop the pressure by a very small amount, then immerse the watch, you should see bubbles appearing from the point where the leak is. At this point you need to be VERY careful, lift the watch out of the water and let the pressure down VERY slowly, allowing the air in the case to escape. If you drop the pressure too quickly you will blow the glass out of its seal and that will spoil your day.
In a second scenario, the watch will seal to around 1 bar but leaks above that. This means the pressure inside the case reaches 5 bar when the air is pressurised to 6. The pressure is dropped slightly and the watch immersed. No bubbles are observed, so the operator feels happy to drop the pressure faster and reaches a point (<5bar) where bubbles are observed. Unfortunately he’s probably dropped the pressure too quickly and the crystal lifts with the watch immersed, that’s enough to spoil anyone’s day. It only takes a small amount of pressure to lift the crystal, trust me on that one.
I always take the movement out and test the case separately, with a watch that’s an unknown quantity its the only safe way to do it. Usually I’ve inspected or replaced the seals so I know what to expect, but I do get surprises. Depending on the watch and design I may test it again carefully after reassembly to confirm that the caseback seal has located correctly, but with most watches its obvious whether its in correctly or not.
It makes far more sense to have watches checked for WR by someone who knows what they’re doing, these machines dan do more harm than good if they’re not used with caution.