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Treatment; Surface clean to remove tarnish. Position replacement turquoises and attach using adhesive.; Metals

Reason: Loan
Description: First a light steam clean to remove general dust and dirt was done (only partially successful). The piston was held at a larger distance (about 8 cm) than usual due to the fragile nature of some of the pearls and present adhesive to keep some in place. Using silver dip applied on a small brush while viewing under magnification (about 20x) locally tarnish was removed from the silver (sides) and gold avoiding contact with the turquoises or pearls. The excess silverdip was dried off with small cotton wool swabs and then was rinsed off using deionised water from a squeezy bottle. At this point one of the turquoise cabochons became detached and was placed in a glass vial to be returned later. To remove residues from the silverdip the object was immersed in (new) deionised water for 45 minutes. A small soft brush was used over the surface to agitate/ lift remaining dirt and possible residue from the silverdip. The object was again steam cleaned after which it was noticed a second turquoise (about 1,2 mm diameter) was missing. This could not be found in the large beaker into which the object had been held during the steam cleaning. Also the immediate floor, gloves, rinsing water (still in the bowl in the fume cupboard), paper bins, U-bend of the sink in the main workshop where the work using the microscope had been done earlier. Floor sweepings were collected and visually checked but with a negative result. The removal of tarnish on the silver surface on the neck appeared to leave a matt white silver surface, though existing earlier photographs do show the neck as silver coloured this could indicate the surface was originally oxidised (and thus coloured black). After discussion with the curator it was decided to replace the missing turquoise with another chosen based on size and colour (though the shape of the cut is slightly different and it has a higher polish) which was adhered with HMG Paraloid B72 (methyl ethyl methacrlylate), as was the detached turquoise. See also photo AN01091731.
Details: Treatment

1 related objects

brooch

Museum number: 1978,1002.840 |
Producer name: BIOG65770 Designed by:Messrs Auguste Blender |
Production date: 1860 |
Production place: Made in:Paris (France)

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