Identifying White Precipitate in Saline Solution
Identifying White Precipitate in Saline Solution
(OP)
Over several months I kept a piece of aluminum coated with polyurethane in a sea salt water solution. Upon inspection I noticed a soft, white substance that formed as clusters at the interface between the polyurethane and aluminum. Attached is an image of the piece; I apologize for the poor quality of the picture.
Does anyone know what the white substance most likely is?
Does anyone know what the white substance most likely is?





RE: Identifying White Precipitate in Saline Solution
David
RE: Identifying White Precipitate in Saline Solution
It is indeed soft and crumbly.
RE: Identifying White Precipitate in Saline Solution
Photo is not good as you noted, but it looks like filiform corrosion is occurring between the coating and the aluminum. Perhaps another photo would help. Filiform corrosion will look like little worms crawling under the surface of the coating.
The crumbly stuff is probably a combination of crystalizing salts from supersaturation as zdas04 noted and oxides/chlorides of aluminum.
RE: Identifying White Precipitate in Saline Solution
RE: Identifying White Precipitate in Saline Solution
i thought this was relevent ...
http://
maybe this thread ...
thread367-289644: Testing for Aluminium Oxide
RE: Identifying White Precipitate in Saline Solution
Does the attached image provide additional insight?
RE: Identifying White Precipitate in Saline Solution
The suggestion to taste it was not intended as a joke. I have regularly tasted things that look like salt build-up to see if they were salty. I don't sprinkle it on a steak, but I do wet my finger, touch the questionable material and put my finger on my tongue. There are materials in the world that could hurt you in that dose, but I've been lucky I suppose. I've frequently been able to redirect an investigation based on that "test". Just as frequently I've had a nasty taste in my mouth for a few minutes.
KimWonGun,
The second picture was a lot prettier, but I can't tell much from it.
David
RE: Identifying White Precipitate in Saline Solution
Does this offer any further insight?
RE: Identifying White Precipitate in Saline Solution
RE: Identifying White Precipitate in Saline Solution
zdas04...same here. Been lucky too, I guess, but chances of toxicity are rather remote...
RE: Identifying White Precipitate in Saline Solution
You've been given some pretty good guesses thus far. But based on some photos and non-specific knowledge of the chemistry involved that's all you'll be able to get.
If you need to KNOW, scrape some off, put it in a little plastic envelope and send it off to a lab from spectroscopic analysis. Then you'll know.
RE: Identifying White Precipitate in Saline Solution
Since my earlier images were too blurry to be much help, permit me to offer one last image made with a different camera for any further insights anyone has into identifying the white powder. I am grateful for the suggestions already provided.
Investing in the considerable cost of spectroscopic analysis may be required later; my current objective is just to report the most likely candidates for further internal discussion.
RE: Identifying White Precipitate in Saline Solution
Patricia Lougheed
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RE: Identifying White Precipitate in Saline Solution
RE: Identifying White Precipitate in Saline Solution
RE: Identifying White Precipitate in Saline Solution
RE: Identifying White Precipitate in Saline Solution