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Water detection stickers on cell phones?

  1. Apr 27, 2008 #1
    does anyone know the chemical process involved with these? pretty much a white sticker and when it gets wet it turns red.
  2. jcsd
  3. Apr 27, 2008 #2


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    I've never seen these stickers on cell phones, and am not sure what it uses if it starts out white. A common moisture indicator used in dessicants is cobalt chloride, which changes from blue to pink as it absorbs water.

    I'm rather baffled about why you would need such an indicator on a cell phone. Afterall, if it's sensitive to low moisture, just going out on a humid day is going to react it. If it requires more water exposure, wouldn't it be rather obvious that it's floating in the pool or toilet bowl?
  4. Apr 28, 2008 #3
    A cell phone moisture indicator is useful because sometimes a cell phone can be salvaged before it is turned on for the first time while waterlogged. If you attempt to turn it on while the indicator is red, the phone will be permanently damaged.
  5. Apr 28, 2008 #4
    They use them for warranty purposes. If the phone breaks and they see that it got wet they will tell you it is your fault and then they won't replace it. You are right Moonbear, whatever it is they are very sensitive to moisture. I don't know if they have got any more advanced lately but the older ones would start to turn just from humidity and body sweat. Most people clear coat them or put scotch tape over it when they first get a phone so that a little bit of water won't mess up their warranty.

    I guess the best bet would be to just make a new sticker or bleach it white. but I was wondering if drying out the substance would do anything.

    Oh and i am just wondering, my friend has a very expensive phone he dropped fishing and we were trying to figure it out. i would never spend money on a good phone and if i did i would have clear coated it the first day.
  6. Apr 28, 2008 #5
    Really? I wish I would have known that a year ago. Although, I suppose that wouldn't prevent water damage after taking a dip in Lake Erie with the phone in my pocket.:rolleyes: I'm such an idiot.
  7. Apr 28, 2008 #6


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    Where are they located? On the inside of the phone somewhere? I've never heard of such a thing. How would that invalidate a warranty if it turns just from normal humidity exposure? But I guess that's a topic for another thread.

    If it's like most moisture indicators, yes, it should change back to the original color if dried...if you can get it off the phone safely. Placing it in an oven set to "warm" (whatever the lowest setting is, usually used for keeping food warm rather than cooking it) should suffice to dry it without damaging it.

    Um, I don't think that's a very honest approach since it really did get immersed in water, not just reacting from humidity. Don't you think clear coating would void a warranty too, since the tampering would be obvious? It's better to buy the added insurance if you're getting an expensive phone and tend to be hard on them.
  8. Apr 28, 2008 #7

    They are usually located on the inside where the battery would be. I image the stickers don't come off easily. Maybe a little heat would take it off but I don't know if it would reattach then. Like I said I'm not doing it but if I did have a nice phone I would try to scam it as well. It's not like they are going to reuse parts of the phone, those phones cost nothing to them and to try to fix electronics that involve chips that are 5x5 mm and have 100 surface mount pins isn't very feasible. It's just another way for them to make money by making the customer at fault.

    And no the clear coat won't void the warranty. No offense to anyone here but the people looking at the phones to send them back are just the people that work at the phone store or the mall. They really don't seem to know a lot of technical stuff especially when you need help with something, nor do they really care that much so it's just a matter of getting it by them.

    Also I have dropped a lot of phones when I clean my pool every summer I always drop the phone in water. I usually dive in and get it, rip the battery apart and blow compressed air in it and it works fine. So if you drop it in the water again undrcvrbro, make sure you disconnect the power and when everything dries out it will most likely be fine again. As long as it wasn't in the water long enough to make somethign short out.
  9. Apr 29, 2008 #8

    "Most useful desiccants can be recycled by thermally-induced drying, for example, in a conventional kitchen oven, or with solar energy. A cost-effective, low-energy, continuous-cycle desiccant dehumidifier or desiccant regeneration system can be easily designed from off-the-shelf component parts."
  10. May 1, 2008 #9
  11. May 2, 2008 #10


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    Probably an encapsulated dye. The water-soluble encapsulant dissolves in water and the water-soluble dye spreads. No, it it probably not reversible.
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