The inside of our kettle is lined in a blue-green deposit. Our water is very hard, but what minerals could cause the coloration?
$\begingroup$
$\endgroup$
4
-
1$\begingroup$ Can you post a photo of your kettle? It appears what you desribe as "blue-green deposit" could be explained in various ways. $\endgroup$– tipaviCommented Jul 16, 2016 at 17:24
-
$\begingroup$ To specify: Are you describing a turqouise crust (rare in kettles) or a rainbow like patina (common in kettles or pots)? $\endgroup$– tipaviCommented Jul 16, 2016 at 17:31
-
$\begingroup$ @tipavi You're absolutely right in that a photo would help clear this up. It's great that there's discussion, though)) $\endgroup$– ZuboCommented Jul 16, 2016 at 23:20
-
$\begingroup$ Over the last few days I have observed a similar phenomenon in our kettle. We also have blue limescale in our kettle i.sstatic.net/5R5AI.jpg. This is in a house in Cologne, Germany built in 2016. It was easy to remove with citric acid but I am also wondering about health implications. $\endgroup$– cgogolinCommented Nov 17, 2019 at 17:24
Add a comment
|
4 Answers
$\begingroup$
$\endgroup$
8
If your building's water pipes are made of copper, that could explain the blue-green coloration. Hopefully the inside of your pipe doesn't look like this, though:
-
$\begingroup$ Unlikely that the kettle is made from copper... ;) $\endgroup$– tipaviCommented Jul 16, 2016 at 15:59
-
$\begingroup$ Unlikely that the kettle is a pipe - you might want to amend your answer. $\endgroup$ Commented Jul 16, 2016 at 16:19
-
4$\begingroup$ The implication would be that the tinge of copper comes from the water coming through the pipes. $\endgroup$ Commented Jul 16, 2016 at 16:36
-
$\begingroup$ Why couldn't the kettle be made of copper? Why couldn't the minerals come from copper piping? I think that's a perfectly logical hypothesis. Also: google.de/… $\endgroup$– ZuboCommented Jul 16, 2016 at 17:05
-
1$\begingroup$ Old buildings have water pipes made of copper - I'll amend my answer to be clearer about that @ToddMinehardt $\endgroup$– IT TsoiCommented Jul 16, 2016 at 17:16
$\begingroup$
$\endgroup$
2
This is not caused by any mineral in the water, but an oxidation of the kettle's steel itself. Several monolayers of metal oxide are stacked onto each other, basically forming a dielectric mirror.
-
$\begingroup$ I think that's a possibility, but certainly not the only one! Wouldn't bet on it $\endgroup$– ZuboCommented Jul 16, 2016 at 17:04
-
$\begingroup$ @Zubo: Looking at your comments above I guess we are talking about different phenomena. A photo might help. $\endgroup$– tipaviCommented Jul 16, 2016 at 17:22
$\begingroup$
$\endgroup$
This might be dangerous! StackExchange is not necessarily the place to check this with.
If this is CuSO$_4$, that's actually mildly toxic. It could also be something like the German "Grünspan", a copper rust that makes a patina on copper house roofs that's got a blue-green color. It is a mixture of copper hydroxide, carbonate, acetate, and maybe others. This is all not good if this is your drinking water.
You should get that checked by professionals. However, ammonia solution in excess should produce a deep blue tetraamine complex with copper(II)-ions, you could try that (although if it doesn't work, that's by no means a safety assurance).
Have a look here for an example of Grünspan:
$\begingroup$
$\endgroup$
Limescale consists mainly of calcium carbonate but can also contain other compounds depending on water composition. These include iron hydroxides which while a white solid gains a greenish tinge in the presence of oxygen. That may explain a green limescale in your kettle.
