# Will putting a watertight dive watch in vacuum seal plastic bag blow out the crystal?

**URL:** <https://boards.straightdope.com/t/will-putting-a-watertight-dive-watch-in-vacuum-seal-plastic-bag-blow-out-the-crystal/508285>\
**Category:** Factual Questions\
**Created:** [August 30, 2009, 9:00pm UTC](https://boards.straightdope.com/t/will-putting-a-watertight-dive-watch-in-vacuum-seal-plastic-bag-blow-out-the-crystal/508285 "2009-08-30T21:00:37Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\
**Post date:** [August 30, 2009, 9:00pm UTC](https://boards.straightdope.com/t/will-putting-a-watertight-dive-watch-in-vacuum-seal-plastic-bag-blow-out-the-crystal/508285/1 "2009-08-30T21:00:37Z")

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I got one of those [vacuum seal freezer bags and the accompanying air sucking](http://www.reynoldspkg.com/reynoldskitchens/handi_vac/en/demo.asp)tool from WALMART the other day and was playing with it last night. It’s a bit difficult to align properly, but when it works it really does encase the bagged object in a hard tight skin of vacuum sealed plastic.

If I use this for metal cased watches I assume this will stop any tarnishing. I did this to a ladies quartz watch last night and it’s still ticking away merrily inside the vacuum sealed bag with the plastic tight against every part of it. If I do this to a dive watch with a screw down crown and water tight (and assumedly airtight) case is there any pressure differential issues I need to worry about that would blow out seals around the crown or damage the crystal?

In other words if the dive watch is a closed, sealed atmospheric environment to prevent water intrusion will producing a hard vacuum around it during the air evacuation process blow out the crystal or damage it somehow? Also the dive watch mechanisms are self winding rotors driving a mainspring, not quartz crystal mechanisms like the ladies watch. I assume a vacuum would not effect the mechanism.

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**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\
**Post date:** [August 30, 2009, 10:00pm UTC](https://boards.straightdope.com/t/will-putting-a-watertight-dive-watch-in-vacuum-seal-plastic-bag-blow-out-the-crystal/508285/2 "2009-08-30T22:00:29Z")

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What metal would a dive watch be made from that would tarnish? Silver?

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**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\
**Post date:** [August 30, 2009, 10:25pm UTC](https://boards.straightdope.com/t/will-putting-a-watertight-dive-watch-in-vacuum-seal-plastic-bag-blow-out-the-crystal/508285/3 "2009-08-30T22:25:51Z")

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You’re not producing a hard vacuum around it, since the flexible bag is moving in to fill the space inside. You’d only need to worry if you were doing this in a rigid container (and probably not even then).