[GreenKeys] Brass Tarnish

[Craig Sawyers]

> The brass is
> tarnished so when a phone plug is inserted, it usually does not
> make good electrical contact without twisting and pushing (to
> break through the tarnish).
>    Now, the poser. Does anyone know of a liquid brass/copper
> polish that can be applied, let sit, and wash off (the board
> could be emerged in water with no problems) to remove the
> tarnish?

Copper-nu.  This is a product that is used in the printed-circuit industry
for cleaning the copper.  I have used it for making space-qualified thermal
crimp joints.  The action is nearly instantaneous.  From their data:

"Kester #5520 Copper-Nu and #5560 Solder-Nu are non-fuming liquid solutions
for removing
oxides, sulfides, carbonates and other contamination, such as etch residues,
from metal
surfaces to facilitate soldering. These stable solutions clean by dissolving
or solubilizing the
contamination for easy removal by water rinsing. The chemical cleaning
action is quite
different form strong mineral acids which etch away valuable base metal and
passivate the
surface by insoluble film formation. Both solutions contain a pink pH
indicator which turns
yellow at pH 3.5 indicating the solution has lost its efficiency."

They say to immerse for between 30 secs and 3 mins, then rinse off with
water.

Craig