"Ray" wrote in message
news:mPy5f.8233$Yk6.3577@trnddc01...
My cleaning lady cleaned a very old and lovely brass lamp that belonged to
my mother. Whatever she did, it looked fine at first, but now green stuff
is gathered in the creases of the embossing. In one or two places, it is
starting to turn black. I managed to rub away most of the black and some
of the green with a toothbrush, but not all, and it is tedious.
Any ideas welcome. Would vinegar and salt help?

She may have used a paste polish or cleaner with ammonia or chlorine in it..
Either one will react with the copper in the brass, if the lacquer is worn
off in places, and produce either copper chloride or another salt, most of
which are colored green. There are some good care hints at
http://www.englishcustompolishing.co...sscopper1.html
which i found on Google. Basically, you could use a small soft brush or
rag, hot water, and mild detergent to get all the traces of of green off,
then use a fine brass polish *very* sparingly, and follow the instructions
above. The engraving tends to hold any compounds, so some care must be used
in completely removing all polish trapped by the grooves.