HOW TO CLEAN AND POLISH A JEWEL ?
Starting from the assumption that in the goldsmith’s field, whether artisanal or industrial, the person who performs polishing specialises in this work with practice and experience, and this determines a specific professionalism: like the gem-setter for mounting the stones, like the goldsmith for making the jewel, or like the engraver.
But in any case, ‘the goldsmith’ in general and not only theoretically, must know how to polish how to set, how to engrave, and then realise with professionalism in a specific discipline
MATERIALS AND EQUIPMENT FOR POLISHING THE JEWEL :
The final stage of jewellery processing consists in cleaning and polishing all its parts, visible and invisible, using brushes and special abrasive pastes capable of making the jewel shiny and brilliant.
This phase, in order to be perfect, requires a great deal of skill in both the simplest objects, and in the most complex or intricate ones, several steps are taken:
In complex jewellery, each individual element is pre-polished in its entirety before assembly of the individual elements, then polished again before assembling them into the jewel as a whole, and then the final step of total polishing.
Traditionally, abrasive pastes with different cutting characteristics are used in polishing. The most common are yellow paste or tripoli, and red paste or lipstick, which respectively ‘cut’ coarser and finer in combination with hard bristle brushes for the former and soft cotton brushes for the latter.
These brushes can be of different shapes and sizes, and are used with a special polishing bench that consists of: a rotating motor, a hood connected to a powerful vacuum cleaner to collect the dust that is formed during polishing and that is mixed with metal residues that are removed during the polishing process, but also to avoid breathing in these residues that can be harmful to health.
(These in any case are just two of the many pastes that can be used on the market.
PROCEDURE FOR POLISHING THE JEWEL :
The first step is carried out by passing the yellow paste over all the surfaces of the jewel, which has previously been prepared with emery sandpaper ready for polishing. We then proceed by weaving the direction of the passage of the brush impregnated with yellow paste over the surface so as to make it as uniform as possible. Through the abrasion, a “cut” is made on the jewel, which is much finer than emery paper and smoothes it evenly. Remember to avoid forcefully touching the edges and protrusions of the jewel as they could wear uncontrollably.
Once the jewel has been brushed all over with the yellow paste, also called ‘rotten stone’ (another name for tripoli), we move on to the second step with the lipstick.
The lipstick, or red paste acts in combination with the softer cotton brush, making a very thin cut invisible to the naked eye that visually appears shiny, mirrored.
We proceed in the same way as in the first operation, weaving the passes over the surfaces in all their parts until they appear mirrored and shiny.
In addition, if the object has points that are difficult to reach with large brushes, there are small brushes with the same characteristics that can be used with bench drills or micromotors, which make it possible to reach those interstices and corners where large brushes would not be able to reach.
Lastly, polishing can be done by hand with a special skein of cotton thread, for all those parts of the jewel that are impossible to reach with brushes, proceeding with the pastes as described above in each small part of the object, one by one.
FINAL PART WASHING THE JEWEL :
After polishing, the jewel must be washed to remove residues of the polishing pastes and eliminate oily parts present by performing the “soaping”. Hot soapy water (approx. 40-50°) is prepared and the jewel is immersed* in the soapy water solution and a special brush is used to rub the jewel all over to remove residues of the pastes remaining from the polishing.
It must then be rinsed under running water and if there are still residues of the pastes, the operation must be repeated. Finally, it is dried in boxwood sawdust.
In workshops and goldsmiths nowadays, ultrasonic baths* are used to wash and degrease jewellery.
Important *To immerse jewellery in hot water one must have knowledge of how to treat any gemstones on the object, as not all of them can be subjected to even the slightest change in temperature; enquire if this is the case from someone more experienced so as not to damage them irreparably.
*Even to use these one must have knowledge of gemstone treatment.
For those interested, all these very important notions are studied in our special applied gemmology course.
See course sheet
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Academy Of Goldsmith Arts