detecting salt

I have an instrument that was dropped in the ocean and recovered. It was supposed to be waterproof but some seawater got inside anyway. Is there an easy way to detect salt residue, to find out which parts of the instrument got wet? Like some chemical that reacts with sodium and changes color? I don’t want to lick it - it’s supposed to be clean but it’s been around some nasty stuff (like Americium-241!!).

It’ll probably crystalize or turn white, or get stickey. Have you ever been to someones house that uses contact lenses. If they’re anything like me (that is they never wipe down the counter under the contact lens case) they’s a big stickey mess under the case. Of course, as long as it’s already wet, could you rinse it off with distilled water?

Well, the exterior of the instrument is pretty much encrusted with salt crystals. But some parts of the inside surface was visibly wet, yet there were no crystals after it dried. I want a more sensitive method. What industry/field would have a salt test kit?

I suppose I could dunk the whole thing in distilled water, but I want to avoid it if it’s not necessary. I know the case got wet, but I want to know if the circuit board inside got wet as well.

A.A. Flame test:D

In the marine cargo transport industry, cargo surveyors often apply a test to determine whether previously wetted cargo was wetted by rain or by seawater, since that may allow blame to be determined.

The test uses silver nitrate. I don’t know exactly how, but I seem to remember it’s a pretty simple matter.

Fluorescent reagents might pick it up, as the metal ions in the seawater will cause quenching and or frequency shifts.
For quick and dirty spot checking, you could just use a 1% solution of silver nitrate in distilled water. If you put a drop of the solution on a salt covered surface you’ll get an immediate white precipitate of silver chloride.

Thanks Princhester and Squink! I’ll try silver nitrate. (Not my favorite substance - somoene once sprayed my car with it as a prank - but I’ll deal with it)