On Tue, 18 Oct 2005 01:31:02 +0100, Bill wrote:

Diet Coke.

I heard that this was good too. I had been trying to clean a similar
intricate statue and tried it with coke. Having a large ultrasonic
cleaning bath that I had tried with various cleaning fluids before I
put 5 litres of coke in, plus the statue and turned it on.

What happens when you VERY rapidly shake 5l of coke? It was most
impressive, Dr Who special effects would have been proud of it.

ROTFL! Sonication was used for degassing solvents for HPLC. Nowadays there
are inline degassers which make life a little easier. Using the sonicator
for cleaning jewelery was a sideline which meant that I always had favours
to call in when needed.

Back to the original question, it is possible to remove the tarnish from
brass with a variety of weak acids, but a strong acid like the mineral
acids will dezincify the surface, changing its appearance. As for
polishing, I cannot think of any magical recipe to do that which does not
contain elbow grease. If you look on the ingredients list for coke,
phosphoric acid is listed and it is this which tackles the corrosion. For
those of you who remember Jenolite (now apparently superseded by a
superior product) that was a mixture of phosphoric and hydrochloric acids
plus a couple of ancillary ingredients.

John Schmitt

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