iain wrote: ↑Thu Dec 07, 2023 12:59 pm I’ve been reflecting on this and thinking about what it is that gives a watch its depth rating. What’s different about a watch rated to 600m compared to one rated at 50m?

Most of this comes down to the design of the actual watch itself. Thickness of the case and crystal, screw down crown and case back, the design of the case where it holds the gaskets so under pressure they stay in position etc.

Are gaskets rated to different depths? Can you fit a gasket of a certain size that’s rated to 600m compared to one made of the same material to the same dimensions that’s only rated to 50m?

If a watch is stripped and inspected for damage to ensure the case back isn’t damaged, screw threads are clean and intact etc. These elements that contribute to the water resistance won’t have changed.

All that has changed during service is that new gaskets have been fitted and you need to check their integrity to ensure they aren’t faulty and have been fitted correctly. The part of the watch where they are seated is exactly the same as it was before.

Therefore all you need to ensure is that they are installed correctly, so would a test to a lower rating then the entire watch prove this?

There is no need to ensure the case back won’t deform at 599m as that’s already been tested.

I think this is largely true. As you stated, I don't think the gaskets are 'rated' but they are sized and the correct size should be installed at service. As I stated in an earlier post, out of the extreme pressure tests I have seen, I don't remember seeing a gasket fail. It was pretty much the caseback first then the crystal usually shatters when they get to 'crush' depth.

This sent me down a gasket rabbit hole and I will need a few days to soak all of this in.

Some points that I learned.

Compression of the gasket matters therefore the torque put on the caseback matters. If there is not enough compression then the gasket will not deform and fill in the irregularities or distortions/misalignment in manufacturing. Too much compression and the gasket will not rebound when the compressive stresses are removed creating a gap between the gasket and enclosure.

Rubber material has a shelf life. Rubber based materials have a shelf life of around 7 years. As the material ages the stress relaxation is compromised. Leads to the same issues as above.

Most of what I was reading was for piping so not directly applicable but I think close enough. One interesting takeaway was that all seals leak. Sometimes so small that the leak can only be detected with a mass spectrometer. This brings to mind the monobloc cases used in watches like the Ploprof. This problem has to be increasingly difficult to deal with when you are talking about helium. I wonder what Seiko designers had to do when they designed the original Tuna which could be used in saturation environments with no helium escape valve needed.

I could't really find anything that would govern the size of a gasket other than that the gasket thickness should be as thin as possible for a given application. This is because the smallest inner diameter allows for a better surface area for pressure to act upon. I'll have to think more about this as I am not 100% what they mean. However, if you make the material too thin there will not be enough material to compress to fill the gaps and imperfections.

Another factor in all of this is the machining inside the 'trough' where the gasket is placed and the part of the caseback that touches the seal. The quality of finish and metalwork here is critical. It shouldn't be too rough or irregular so that there is no leak-path around the gasket. It is resting on an ostensibly smooth surface.

EDIT to Add: This bit is in every manual for a sports model that CW makes.

Although your watch has been through vigorous static pressure
testing, it is worth remembering that there are many variables that
can affect the water resistance of your watch.

This, to me, would indicate that CW does not do batch testing at the manufacturing stage but tests every watch. Otherwise they would say something other than 'your watch'.

Coming back to the OP and follow-up comments, I can't believe that 3atm is the "industry standard". Though it may be the lowest common denominator. What would the point be in buying a watch with 600m WR if, after the first service, that no longer applies? Yes, I know that most people will never use their watch at depth, but that's not really the point is it? 3atm is barely washing your hands level of WR.

rkovars wrote: ↑Thu Dec 07, 2023 4:57 pm
Rubber material has a shelf life. Rubber based materials have a shelf life of around 7 years. As the material ages the stress relaxation is compromised. Leads to the same issues as above.

Rubber as a gasket material is in the past. The gasket material for the caseback/crown is likely to be Neoprene or Viton, both are extremely durable and flexible for a very long time.

The 'o' ring seals on the fuel injection rail of my car are 35 years old now and are still fine.

rsg wrote: ↑Thu Dec 07, 2023 7:39 pm

rkovars wrote: ↑Thu Dec 07, 2023 4:57 pm
Rubber material has a shelf life. Rubber based materials have a shelf life of around 7 years. As the material ages the stress relaxation is compromised. Leads to the same issues as above.

Rubber as a gasket material is in the past. The gasket material for the caseback/crown is likely to be Neoprene or Viton, both are extremely durable and flexible for a very long time.

The 'o' ring seals on the fuel injection rail of my car are 35 years old now and are still fine.

I hadn't thought of this so I checked a few watch parts catalogs and watch part suppliers. Almost all of the o-rings and gaskets were some form of rubber (FKM, silicone, etc). Even OEM parts. It is probably a cost/performance thing. The manufacturers are expecting a service to happen on a regular basis and are designing requirements around that assumption. It will be interesting though if the NANO lubricants being developed by Daniels ever work out. They are envisioning a watch that never needs service unless something physically breaks. The idea is that the pivots and jewels keep swapping nanoparticles back and forth so that the lubricant never goes away.

redmonaco wrote: ↑Thu Dec 07, 2023 12:48 pm

jkbarnes wrote: ↑Wed Dec 06, 2023 2:54 pm That explanation makes sense, I guess. I guess it also means that if you were a working diving professional, you’d need to take your watch to a specialist to have it tested to its full depth rating?

What? Immediately after getting the makers full service???

I guess I didn’t express myself clearly. I meant if I was a professional diver who relied on his dive watch, I wouldn’t bother with a manufacturer’s servicing if they didn’t pressure test to the stated depth rating. I’d get my servicing and pressure testing some place that did.

jkbarnes wrote: ↑Thu Dec 07, 2023 9:16 pm

redmonaco wrote: ↑Thu Dec 07, 2023 12:48 pm

jkbarnes wrote: ↑Wed Dec 06, 2023 2:54 pm That explanation makes sense, I guess. I guess it also means that if you were a working diving professional, you’d need to take your watch to a specialist to have it tested to its full depth rating?

What? Immediately after getting the makers full service???

I guess I didn’t express myself clearly. I meant if I was a professional diver who relied on his dive watch, I wouldn’t bother with a manufacturer’s servicing if they didn’t pressure test to the stated depth rating. I’d get my servicing and pressure testing some place that did.

Yes I agree. The problem is that CW don't tell you that they don't/can't pressure test to above 30m. Their website just states that all watches are pressure tested before being sent back. Now I would have thought that the average person would expect that if they are offering a repair/servicing facility for their dive watches then the pressure test would be to the specification of the CW watch, not just to "hand wash" rating...

redmonaco wrote: ↑Fri Dec 08, 2023 12:51 pm Yes I agree. The problem is that CW don't tell you that they don't/can't pressure test to above 30m.

It’s a problem if I’m Joe Schmoe average consumer and watch owner operating on assumptions. If I’m a diver whose life potentially depended on the WR of my watch, I’m not making any assumptions. I’m inquiring about the specifics before I ever drop the watch off. I’m probably even working with someone who specifically caters to divers.

jkbarnes wrote: ↑Fri Dec 08, 2023 1:25 pm

redmonaco wrote: ↑Fri Dec 08, 2023 12:51 pm Yes I agree. The problem is that CW don't tell you that they don't/can't pressure test to above 30m.

It’s a problem if I’m Joe Schmoe average consumer and watch owner operating on assumptions. If I’m a diver whose life potentially depended on the WR of my watch, I’m not making any assumptions. I’m inquiring about the specifics before I ever drop the watch off. I’m probably even working with someone who specifically caters to divers.

Yes, I get you. But this is relevant to all of us that aren't professional divers and just use a watch in the pool a couple of times of the year. After all you wouldn't wear a C1 moonphase in the pool and That has a 3bar rating...

Maybe I am being paranoid now but after looking at the original receipt after service I am thinking that there may have been some deliberate misdirection here...

Website FAQ:




First receipt after service:



Looks good and I wouldn't have been any the wiser EXCEPT I had to send it back because the watch hadn't been serviced correctly. And it was on the Second receipt I see:



So, there you have it. Was I/all of us being deliberately misled? Did they "forget" to include the pressure rating the first time or did they include it in "error" the second time...

I must admit this has, (after owning upwards of 40 CWs over the years)made me seriously rethink my relationship with CW... :0(

I just found this test result to one of my EB’s tested last year. As you can see it was tested to 10atm’s. The watch is actually rated to 20atm’s. I really have no idea how the test functions but I know EB wouldn’t send out questionable watches to customers. The Co tagline is ‘worn by adventurers’, they pride themselves on testing every new watch they sell, not batch testing. I’m pretty sure every pressure tested watch would have to be able to meet its manufactured rating. They know their watches are put through their paces and, more than that, pride themselves on their durability.

I hope CW are able to offer you the assurance you seek.

@strapline

How do they test -0.7 and even +1.0 come to that?

+1.0 is just ambient, isn't it?

I used to have a really good video that described how a three stage pressure test works (there are three different testing rigs involved). It involves both wet and dry tests in both pressurized conditions and a vacuum. For the life of me I can't find it.

This article is well worth the read and describes the steps really well. This is the setup my local watchmaker has.

https://www.hodinkee.com/articles/under ... ce-testing

This video is from Bob's watches that describes pretty much the same process. The video I mentioned above took the time to go through each step in detail and I wish I could find it. I'll keep looking and post it here if I find it.




Longer video that shows stuff better but still not the one I was thinking of above.




As a side note: Here is how Rolex tests the DeepSea Challenge (11000 m).

https://www.hodinkee.com/articles/how-r ... you-me-and

No matter what CW says is the industry standard, and it's pretty obvious 30m is not the industry standard for 200m rated dive watches, if they haven't tested the watch to its advertised depth/pressure then it's not fit for purpose, irrespective of whether you dive or not.

Shabby practice in my opinion. Do the job properly or advertise the watch as having 30m water resistance.

Interesting video here, about Jody's factory visit.
Very impressive.

At 7:42 there's a bit about pressure testing, worth looking at in the light of this discussion.

https://youtu.be/QnQXSIraR4I?si=ZM4Rv4DNswm0aQas

"If the watch is found has failed it's pressure test, we will personally reach out and let you know"

Well, that's comforting, isn't it?

As well as being rather badly written. I'll have to take my curmudgeonly head off before I start on the use of "reach out" ...