Page 42 - Bullion World Issue 1 May 2021

Bullion World | Issue 01 | May 2021

Determination of the

Silver Content of Silver

Plated or Blanched

Silver Alloys.

For finishing purposes silverware is
often plated or blanched. In the plating
process, a pure silver coating is applied
to a silver/copper alloy. This produces an
attractive, white satin sheen. Blanching Mr. Bharat Patil
achieves the same effect by chemically Fischer
removing copper from the topmost layer
of the silver/copper alloy. The result of
both methods is a veneer of much higher Using a measuring application which “ Using specialized
silver content than the substrate, which looks for a silver coating atop a applications with the
complicates the determination of the silver/copper alloy, FISCHER X-ray
fineness, and therefore, of the value of fluorescence instruments allow for the GOLDSCOPE SD® 520
the silverware. non-destructive determination of both makes it possible to
the thickness of the silver coating as well
The only foolproof method for correctly as the fineness of the base material. This determine the fineness
determining the silver content of silver- works accurately for silver-plated items of the substrate and
plated or blanched silver/copper alloys because the silver content in the plating the thickness of the
is to test the base material directly, for is consistent. However, with blanching covering layers of
example, by grinding or sawing down the silver content decreases steadily as
into it, since non-destructive standard the distance from the surface increases both silver-plated and
analysis with X-ray fluorescence (XRF) which makes the determination much blanched silverware –
shows erroneously high silver content more difficult. quickly, accurately and
due to the increased concentrations at
the surface. non-destructively ’’

42