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I've heard the advice that WD40 is designed to repel water, and hence, it can supposedly be used to mitigate water damage in electronics. Such as for a device that was submerged, instead of simply allowing it to dry, which might take a very long time, especially in tight places, under components, etc, and allow more oxidation to occur. Spraying WD40 into the device and the tight spaces, supposedly mitigate this problem to some extent.

Is there any merit to this at all, or will it simply make the problems even worse?

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    \$\begingroup\$ I can't answer that question, but I'm pretty sure that a generous application of isopropyl alcohol (IPA) will work better than WD40 for this purpose. IPA washes away the bulk of the water, mixes with the remainder, and evaporates, leaving no trace. With WD40 you would end up with an oily mess that would probably need to be washed with IPA anyway. \$\endgroup\$ – Dampmaskin Sep 12 at 13:01
  • \$\begingroup\$ don't do it. It leaves a greasy residue and also can badly damage carbon pots etc. If you want t dry something out, putting it in a cotton bag in a bag of rice works well (the rice absorbs the water). Take out batteries first! \$\endgroup\$ – danmcb Sep 12 at 13:32
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    \$\begingroup\$ WD40 is also full of solvents and hydrocarbons which would most likely degrade some device packages. As others said, use IPA for emergency drying, use a hydrophobic conformal coating if you are designing a board to get wet. \$\endgroup\$ – Dean Franks Sep 12 at 13:39
  • \$\begingroup\$ @dmb I thought that thing about rice was an urban myth. I don't think rice is going to work nearly as well for this as 99% IPA, even if rice does work. \$\endgroup\$ – Hearth Sep 12 at 17:08
  • \$\begingroup\$ @Dampmaskin When in doubt, apply IPA! \$\endgroup\$ – winny Sep 12 at 19:54
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The standard method I have used is to wash in distilled or de-ionized water. Then put into a bath of iso-propyl alcohol, often by submerging the board for some time. Air dry for a while to get rid of most of the IPA, and then put into a temperature controlled oven at 60degC for a few hours.

Unfortunately, if batteries were connected and the device powered when it was submerged it may have caused damage especially if it was saline. You will just have to try.

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  • \$\begingroup\$ I would think that just the oven would do a pretty thorough job of getting rid of moisture, no? \$\endgroup\$ – danmcb Sep 13 at 18:08
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    \$\begingroup\$ Not if there were any dissolved solids in the water, especially if they had the tendency to adsorb water from the atmosphere. That's why the first wash is water and not IPA \$\endgroup\$ – Dirk Bruere Sep 13 at 22:11
  • \$\begingroup\$ Also, if that water isn't clean, baking with the "dirty" water would increase the corrosive damage done. That'd be extremely counter-productive, @danmcb \$\endgroup\$ – Marcus Müller Nov 17 at 15:26
  • \$\begingroup\$ @danmcb If the water is dirty with solids that do not dissolve in either water or IPA it suggests they are non-ionic and probably poor conductors or insulators. \$\endgroup\$ – Dirk Bruere Nov 17 at 16:02

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