Limescale on gold-plated taps.

Suggests to me that the "gold" plating isn't gold; or that the plating is so thin that it's microporous and that the acid will penetrate releasing bubbles of gas from the base metal.

I don't know - however, all the stuff I've seen so far says "do not use with gold plated taps" OWTTE.

What do you think the "base metal" is, that this so-called "gold" plating is applied on, eh?

If the tap material is brass, alloy of copper and zinc, the zinc is easily dissolved by dil. hydrochloric acid, and hydrogen is released. Googling for gold plating is quite interesting.

So how do I get b;ue/black colouration off my cheapo chrome-plated B&Q mixer taps. Descaler, bathroom cleaners, creams seem to have no affect.

rusyt

I though the test for gold was to see if it dissolved in aqua regia?

I quote;

"Aqua Regia is a mixture of hydrochloric acid and nitric acid. It can dissolve gold, which single acids alone cannot do. Here we see that each of the acids separately has no effect on the gold but a mixture of the two dramatically reacts with the gold. To three samples of gold are added (1) concentrated hydrochloric acid (2) concentrated hydrochloric and concentrated nitric acids and (3) concentrated nitric acid. The gold reacts only with the concentrated acid mixture which is referred to as aqua regia (royal water)."

Dave

Something automotive, I should think. See your local motorbits sho for chrome cleaner/polisher.

Well, yes, it will also dissolve most things including complete taps. However, I do not *want* to dissolve my taps. I want to remove some limescale from them. I saw that all the Supermarket products say "don't use on gold plated taps", or words to that effect, so I just asked what *would* be suitable to use. That's all. It seems no-one knows!

I would try vinegar (cold to start with). The trouble with taps is that there is no "inconspicuous area" to test first but maybe round the bottom edge?

Lemon juice

Citric acid from the chemist might be cheaper. Keeping it on the tap long enough for it to work is another matter.

I have a bottle of "hagesan blue" from HG systems in front of me, which I bought from the local plumber.

It consists of 5-30% phosphoric acid and while it warns against use on marble and similar surfaces, gold is not mentioned in the exclusions. The instructions do warn against using the abrasive side of sponges on gold plated surfaces, so by implication gold plating is OK as long as it is treated gently.

John

Gold is resistant to phosphoric acid, but the worry is that if there is a perforation in the plating, it might set up an electrochemical cell and attack the base metal. Hydrochloric acid I would not recommend as the chloraurate ion is one of the few soluble forms of the metal. For those with inquiring minds, the Purple of Cassius is but one of the strange things gold can do:

John Schmitt

Get a water softener and after about 3-6months the existing scale had washed away and no more scale forms. My shower doors, took about 6-12months for all the scale to go away and now stay completely clear.

Getting it from the chemist without having to jump through multiple hoops blindfold to convince them you are not cutting certain drugs with it might be more of a problem.

Mix to a paste with flour.

Or wrap the tap with ordinary bandage or stockinette and soak it with the chosen acid.

If you are cutting drugs, just use Vim. ;-)

John Schmitt

Or use wallpaper paste with citric acid dissolved. Mineral acids tend to mess up the typical compounds, but citric will (I think) leave them alone.

John Schmitt

I'm not but the merest mention that I sold cough sweets for 1p more than I paid for them (yet still making a loss of 50p on the deal) prompted Dr Dribble to accuse me of being a drug dealer and a thief.

Is Vim still available?