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Thread: Hytrel plastic seal failures

  1. #1
    Grand Master
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    Hytrel plastic seal failures

    Just experienced two cases of gasket failure on two modern dive watches with 200m water resistance, something I’ve not come across before so its fair to say I was surprised.

    Both involved the white plastic ‘ hytrel’ seals used to hold the glass in place, I was under the impression these seals lasted indefinitely, especially if they’re not disturbed, but now I know otherwise. Hytrel is a flexible thermoplastic developed by Dupont, a bit like hard polythene, its flexible but not like soft rubber. It was patented but possibly the patent has expired and generic manufacturers are producing it to a lower standard?

    First watch was a 5 year old Steinhart Oceanblack, owner had bought it new, the watch had never been worked on or disturbed. It started misting up and had obviously let water in. I agreed to sort it out and suspected the crown seal had failed or the owner had inadvertently left the crown unscrewed. After removing the movement I replaced the crown and caseback then pressure tested it to 6 bar. This revealed a leak around the glass so I pressed the glass out and investigated. The white hytrel seal was still located in place, but when I looked closely I could see a couple of cracks. When I attempted to remove it the seal snapped and broke into pieces, what should’ve been flexible plastic had become very brittle and bore no resemblance to its original state.

    By coincidence, I had a TAG quartz ladies dive watch on the bench that needed the movement fixing. I tested this one to 6 bar and was dismayed to see a leak around the glass! Sure enough, I pressed the glass out to reveal exactly the same problem, a white plastic hytrel seal with a crack in it. When I removed it the seal was in the same state as the Steinhart one, the plastic had become very brittle and snapped when disturbed.

    A new seal is on order from TAG, no problems there, but Steinhart have proved totally unhelpful. After several exchanges of e-mails they’ve decided not to supply me with a replacement seal; initial response was promising but my request for the parts was met with a stony demand to ‘send them the watch’, I’ve explained the problem and offered to send the remains of the seal for inspection but they haven’t responded; a very disappointing attitude from a small manufacturer I held in high regard. Fortunately I’ve managed to modify a generic seal, the glass is now a very tight fit and the watch has passed a 6 bar test with flying colours. Spending 1 hr trimming the seal was somewhat cathartic and I had the satisfaction of fixing the problem......I would’ve preferred the extra hour to do something interesting, thanks Steinhart!

    Two similar seal failures with the same material, what’s disconcerting is the change in the plastic, its gone from pliable to completely brittle. If I hadn’t seen it myself I would’ve been highly sceptical, I don’t believe the service life of these items should be as short as 5 years. Earlier this year I took a 70s Omega with a hard plastic/nylon seal apart and that was fine (albeit discoloured), a replacement wasn’t available so
    I re- used it, that passed a 3 bar test with no problems and the seal material was still pliable after 40+ years.

    Really didn’t expect to see problems with a modern seal material, this has surprised me, best advice I can offer is to check water resistance more frequently if a watch is deliberately exposed to water.

  2. #2
    Grand Master Chris_in_the_UK's Avatar
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    I am not surprised that a seal has failed at the ages yo mention Paul.

    They are relatively cheap and why not just replace?
    When you look long into an abyss, the abyss looks long into you.........

  3. #3
    Grand Master
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    Quote Originally Posted by Chris_in_the_UK View Post
    I am not surprised that a seal has failed at the ages yo mention Paul.

    They are relatively cheap and why not just replace?
    They're relatively cheap, but that doesn`t hide the fact that the material itself is degrading in a relatively short space of time. Replacing seals as a matter of course is good practice, but they shouldn't degrade like this.

    Omega use a different type of seal material in the SMPs I`ve worked on, I`ve never yet seen a problem despite the watches being 15+ years old.

    The Steinhart is rated at 300M WR, after 5 years that's gone down to zero, not good in my opinion. I suspect the hytrel isn`t the same quality/composition, I would expect this stuff to last many years. It isn`t even exposed to UV because it's shrouded completely by the bezel.

  4. #4
    Grand Master oldoakknives's Avatar
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    I think it's pretty poor that they fail at that kind of age. And Steinhart's attitude is even poorer.
    Started out with nothing. Still have most of it left.

  5. #5
    Master earlofsodbury's Avatar
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    You have to wonder if the material was actually anywhere close to spec. Both watches are almost certainly using Chinese-sourced parts, and are perhaps assembled there. Sad to say, there are no shortage of unscrupulous operators therein who wouldn't hesitate to supply a styrene or somesuch kind of brittle, fragile substitute.

    Shame about Steinhart's snotty attitude.

  6. #6
    Grand Master
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    Can you not source a vitriol rubber gasket of similar size, they seem to last forever!!

  7. #7
    Grand Master
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    I suspect the real issue here is the quality of the hytrel, I can’t believe the change from pliable to brittle over a few years is a normal characteristic of this material. Nothing wrong with the design, most watches thesedays have the glass held in place by a tight interference fit against a plastic gasket. Some 70s Omegas used a similar design of plastic gasket for casebacks, usually a red or green material that seems to last 20+ years without deteriorating, the principle and design is fine. The materials have to be slightly compressible but not as soft as rubber, all’s good provided the physical properties don’t change with age.

    What we don’t know is whether this problem has been recognised and addressed by the manufacturers, what I’ve seen is the performance of seals fitted over 5 years ago and I would hope the problem has been recognised and resolved. Manufacturers will obviously remain tight- lipped so there’s no point in asking the question.

    As for Steinhart, Ideally I should’ve discussed the problem by phone, that may have been more productive. Given the language barrier I didn’t do this, I stuck with simply worded e-mails which I relied on them translating correctly. I was asked to confirm my credentials as a repairer and clearly was unable to satisfy them, hence the unhelpful reply. I’m giving them the benefit if the doubt here, initially they seemed positive but that changed abruptly. I’m impressed by their watches, they’re excellent value for money, but they could certainly be more helpful regarding parts supply.

  8. #8
    Master ordo's Avatar
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    The quality of the gasket is definitely bad.

    I've had watches that were many decades old and had decades old gaskets (sometimes the original ones) and were still in good condition. Some would have probably passed the tests as well.

    I wouldn't be surprised if the gaskets were outsourced somewhere to Asia. Even that doesn't mean that they should be crap but what I'm reading here about new gaskets (a few years isn't old for such a part that's supposed to resist the test of time) is really bad and has repercussions on people's watches beacuse some seemingly water resistant watches will have their gaskets fail and then the whole watch will need repairing. (replacing the dial and hands that can get damaged by water, servicing or replacing the movement, etc.) All this translates into added costs and headaches for some people.

    A watch that costs a few hundred dollars should NOT have such problems. Hell I've had chinese-made watches or cheap Seikos that had no such issue.

    Shameful! I Hope that you insist on this matter and maybe get to the bottom of this. Maybe there was a bad lot in the production line of those gaskets.

  9. #9
    Master bobbee's Avatar
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    Could it be a form of built in obsolescence?
    If just a small percentage of owner's whose watch seal fails just after the guarantee ends, then buy a new watch instead of getting the old one fixed, the manufacturer is quids in.

  10. #10
    Master
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    Quote Originally Posted by bobbee View Post
    Could it be a form of built in obsolescence?
    If just a small percentage of owner's whose watch seal fails just after the guarantee ends, then buy a new watch instead of getting the old one fixed, the manufacturer is quids in.
    This is happening over most product manufacturing from overseas suppliers. Lack of research and development and experience seems to be the cause, plus the replacement sales mean more profit! More landfill!

  11. #11
    Master IAmATeaf's Avatar
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    Quote Originally Posted by bobbee View Post
    Could it be a form of built in obsolescence?
    If just a small percentage of owner's whose watch seal fails just after the guarantee ends, then buy a new watch instead of getting the old one fixed, the manufacturer is quids in.
    What so they randomly throw in a dodgy seal, I very much doubt that.

    What’s more likely is that 5 or so years ago they changed supplier of these seals. Paul’s emails have probably put them into what the shit- defensive mode as they may not have been aware of of problems with the seal? Just my guess.

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