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Clearly, gold is dissolved from the surface in the process. This is small if the initial surface
is good. Chains and all types of jewellery can be electropolished. The process does not
discolour the jewellery, even at solder lines. Good rinsing and the use of a brightening
chemical solution are recommended after electropolishing.
The gold that is dissolved in the electrolyte from electropolishing can be recovered. For
cyanide-freesolutions, the electrolyte is treated with sodium hydroxide until a pH of 5 is
attained. Then a special reducing compound is added and gold is precipitated from
solution. It is allowed to settle and filtered off. More sodium hydroxide is added to the
remaining solution until pH 5-7 is reached and then safely disposed of down the drain.
The gold slime filtered off is dried, mixed with borax flux and melted. It is poured off and
allowed to solidify into a small bar or button. For cyanide solutions, the gold can be
precipitated by additions of zinc or aluminium dust.
Electropolishing of gold jewellery can be done as a single finishing step but, more often,
it is part of a multistep process involving mechanical polishing as well.
The advantages of electropolishing are:

 It is quick
 It can polish complex shaped items and contours will be preserved
 Recovery of dissolved gold is easy Its disadvantages are:
 Only metal is removed from the surface. Defects such as casting porosity are
made more evident! This can be advantageous in identifying faulty jewellery.
 It will remove very small defects (1-2 microns) but not larger defects.

Concluding remarks

Electroplating

We have discussed the basic principles of electroplating and some of the factors affecting
the process. We have also discussed the equipment requirements.
As we have seen, electroplating of jewellery is a very versatile process and one can obtain
gold coatings of varying colour, appearance, properties and caratage as well as pure gold.
It is a quick, cheap and easy process to operate.
It does not require expensive equipment, but it is worthwhile to buy good quality
electroplating salts from reputable suppliers. Such salts are specially formulated to give
good performance.
Many gold plating processes use toxic cyanide electrolytes. Care must be taken in their
use and disposal.
Electropolishing

We have also discussed the basics of electropolishing. It is a process finding increasing
use once more, often in combination with mechanical polishing.