We have several quart containers of coins covered
with residue. These coins were at the bottom of a water fountain and were
given to a charity; not for a collection, but to cash in for face
value. Do you have an easy solution to removing the residue?
Since you did not describe the residue, I shall assume it is either algal or
hard-water scale. Swish the coins around in Clorox solution. That will
algae residue. Follow that treatment with a swish in hot water to which a
dish detergent has been added. Rinse with plain water.
If the residue is from hard water you can remove the scale by rinsing the
in (full strength) white vinegar followed by plain water.
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Update: June 2012