Hacking the Casio F-91W to Handle 1000 Psi

Re:Hacking the Casio F-91W to Handle 1000 Psi by gnopgnip on Sunday June 02, 2019 @10:36PM (#20079972)

Mineral oil breaks down latex quickly. What material is used for the seal? Oil expands and contracts with changing temperature. An air bubble will appear soon after if there are no special steps taken to prevent this.

The real advantage of an oil filled face is the greatly increased readability of the watch.

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Re:Hacking the Casio F-91W to Handle 1000 Psi by jhoechtl on Monday June 03, 2019 @03:55AM (#20081237)

True. There is a Liquid you can put on top of eg marmalade which seals it from air. I think it is a from of liquid silicone (mind the final _e !) which I think is not aggressive to rubber.

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Re:Hacking the Casio F-91W to Handle 1000 Psi by sq_ on Monday June 03, 2019 @04:26AM (#20081361)

Did a little research, and it seems like pure silicone oil is much less aggressive to rubber/latex than mineral oil (and you can get it from Amazon pretty cheaply).

Does anyone have any idea what the chemical differences between the two are that affect how they interact with rubber? I’d love to learn more.

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Re:Hacking the Casio F-91W to Handle 1000 Psi by ncmncm on Monday June 03, 2019 @10:11AM (#20083224)

Good point.

Mineral oil, contrary to the remark in TFA, is 100% organic. Unlike olive oil, though, it's saturated. Does that matter? It's not exposed to air, so no. But olive oil goes cloudy when cold.

The watch is unlikely to have latex in it, but quite likely to have silicone parts and seals that might soften in silicone oil.

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Re:Hacking the Casio F-91W to Handle 1000 Psi by dvt on Monday June 03, 2019 @12:58PM (#20085378)

> Mineral oil, contrary to the remark in TFA, is 100% organic.

Thanks for the correction! From what I was reading, olive oil goes rancid (and acidic; but mineral oil does not).

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Re:Hacking the Casio F-91W to Handle 1000 Psi by ncmncm on Tuesday June 04, 2019 @04:24PM (#20098868)

Olive oil, like any unsaturated oil, may go rancid on exposure to air. But in a sealed watch there will not be enough air.

("Organic", outside of agriculture, means "composed of carbon compounds". In practice, that usually means compounded by something alive, because life has been at the carbon for a long, long time.)

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Re:Hacking the Casio F-91W to Handle 1000 Psi by swsh on Monday June 03, 2019 @06:22AM (#20081785)

No idea what the stock seal would be made from.

Nitrile is commonly used in hydraulics as natural rubber doesn't play nice with hydrocarbons.

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