How does this scale collector work?

[Vlad Soare]

Hi guys,

Really off-topic issue, as far from Mustangs as it gets, but who knows, maybe there are some chemists among us who could enlighten me.
I have a Tefal steam ironing station which has a neat scale collector. You don't have to use distilled water to avoid scale deposits. You can use tap water with it - in fact, the manufacturer even advises you to use tap water instead of distilled. From time to time you just pull out a sort of metal spoon, in which all the scale from the water will have been collected as a fine powder. Throw the powder away, rinse the spoon, put it back, and that's it.
See in this video what I'm talking about:



How does this actually work? What's the physical or chemical process that causes the calcium carbonate to collect so nicely in that spoon, instead of just sticking to everything it comes in contact with, as it usually does?

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[CrazyHippie]

Hi guys,

Really off-topic issue, as far from Mustangs as it gets, but who knows, maybe there are some chemists among us who could enlighten me.
I have a Tefal steam ironing station which has a neat scale collector. You don't have to use distilled water to avoid scale deposits. You can use tap water with it - in fact, the manufacturer even advises you to use tap water instead of distilled. From time to time you just pull out a sort of metal spoon, in which all the scale from the water will have been collected as a fine powder. Throw the powder away, rinse the spoon, put it back, and that's it.
See in this video what I'm talking about:



How does this actually work? What's the physical or chemical process that causes the calcium carbonate to collect so nicely in that spoon, instead of just sticking to everything it comes in contact with, as it usually does?

It's possible that the inner surfaces of the iron are non-metallic or teflon- coated such that when calcium salts precipitate, they can't bind to any surface, so they simply fall to the bottom of the tank into the collector. There also may be an electrostatic device as part of the iron. There are electrostatic water hardness devices that can be used in copper home plumbing systems that resist hardness salt deposition. It's certainly interesting.

 

[Vlad Soare]

I'm not sure about the coating, because the thing that's most prone to scale deposits, and where scale causes the most amount of trouble, is the heating element. And that cannot be coated (at least not in a thermal insulator like teflon). But with the electrostatic thing you may be on to something.

 

[Jimmy Dean]

I'm not sure about the coating, because the thing that's most prone to scale deposits, and where scale causes the most amount of trouble, is the heating element. And that cannot be coated (at least not in a thermal insulator like teflon). But with the electrostatic thing you may be on to something.

not really the case, the element can be surrounded by a ceramic. can take a second to heat up, but once heated works very well, and certain ones scale would find impossible to build up on.

or the element is a material with large thermal expansion, so the scale builds up when it is hot and expanded, and as it cools and contracts it breaks large sections of the scale off. I've seen similar happen unintentionally around some alloy furnace tubes, they'd scale up during use, but any time the furnace shut down the scale would break off as they contracted and moved.

 

[Vlad Soare]

That makes sense. Thanks!

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