Re: Help... Descaling Cimbali M27 & need advice
Gday Borat....
Why the brass components turn Pink is because that is the natural colour of clean (non-oxidised) copper metal. The mild acidity of the Citric Acid bath removes the Zinc from the Copper/Zinc Alloy at an atomic level, which results in an outer layer of pure copper metal maybe only a few atoms in thickness. So long as you thoroughly rinse the acid from the metal after the water-scale has been removed, further reaction should cease.
Theres no real need to polish the brass parts back to the parent metal unless you dont particularly like the colour of the copper. Over time the copper will oxidise and develop a dark patina anyway. Where you see a pinkish tinge on other metals such as nickel (dont think copper will deposit on chrome), e.g. this is due to electrolytic deposition as a result of dissimilar metals being present in the acidic solution. You should be able to polish this off without too much problem...
Hope this is helpful...
Mal.
Originally posted by 4548554653161514270 link=1245413520/10#10 date=1245720550
Why the brass components turn Pink is because that is the natural colour of clean (non-oxidised) copper metal. The mild acidity of the Citric Acid bath removes the Zinc from the Copper/Zinc Alloy at an atomic level, which results in an outer layer of pure copper metal maybe only a few atoms in thickness. So long as you thoroughly rinse the acid from the metal after the water-scale has been removed, further reaction should cease.
Theres no real need to polish the brass parts back to the parent metal unless you dont particularly like the colour of the copper. Over time the copper will oxidise and develop a dark patina anyway. Where you see a pinkish tinge on other metals such as nickel (dont think copper will deposit on chrome), e.g. this is due to electrolytic deposition as a result of dissimilar metals being present in the acidic solution. You should be able to polish this off without too much problem...
Hope this is helpful...

Mal.





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