the liquid I refered to by "bleach", is called "LEJIA" in Spanish:
it's a colourless liquid (maybe a slight yellow hue) that is in
every home (at least here) for washing and for cleaning floor
tiles, specially in bathrooms. When I looked in the dictionary for a
translation the first word that came up was "bleach". The second
word was "LYE". If both words refer exactly to the same chemical,
well, there might be a few "weakened" pieces around in my city.
However, the "lejia" totally disolved the broken drill bits, and I
didn't noticed any discoloration on gold (white or yellow, always
18k) or porosity over the surface or soldered joints.
But Please, Please, if lye is the same as bleach, let me know to
stop using this way of disolving ferrous bits on gold.
Fernando F. Escudero, Spain.