Weight of silver test. Samples of type I items shall be tested in accordance with the proper paragraphs below that specify the base metal, as applicable, or the alternate method for compliance with the minimum weight of silver requirement in table II. Any plating weight that falls below the specified limits shall be considered noncompliant. Each of the selected samples shall be tested as specified and the weight of silver recorded. All the recorded weights for the same type of item shall be added together and the sum averaged to determine compliance with table II. The surface plated area specified under “Thickness of silver” shall be determined in accordance with the manufacturer’s commercial practice for the determinations on the same or similar items.
On nickel brass. The 72 samples shall be thoroughly cleaned, rinsed, dried and weighed. They shall then be introduced into a suitable vessel containing a mixture of 19 parts by volume of C.P. concentrated sulfuric acid (sp.gr. 1.84) and 1 part by volume of C.P. concentrated nitric acid (sp.gr. 1.42), the mixture having been heated (e.g., on a sand bath) to 176 degrees Fahrenheit. The stripping bath shall be kept covered when not in use to prevent absorption of water. The samples shall be kept in the solution until all the silver has been dissolved, as indicated by the dark color over the entire surface. The samples shall then be thoroughly rinsed, Cried, and reweighed. The loss in weight shall be considered silver.
On brass and stainless steel. The 72 samples shall be thoroughly washed, rinsed dried, and weighed; samples shall then be hung as anodes in a solution containing 30 g/L (4 oz/gal) of sodium cyanide, in which an iron or silver cathode is suspended. A potential of 3 to 4 volts shall be applied and the samples shaken or the solution agitated until all the silver is dissolved. The samples shall then be thoroughly rinsed, dried, and reweighed. The loss in weight shall be considered as silver.
Alternate method. Randomly select and weigh any 108 pieces of the type of item to be tested before plating, record the weights, and calculate the average. Repeat the same procedure with any 108 pieces of the same type of item randomly selected after plating. The difference between the averages shall be considered the weight of silver present. Calculate the weight of silver in troy ounces per gross for compliance with the minimum requirements in table II.
Thickness of silver test. Thickness of silver shall be as determined as follows for compliance with the requirements of this CID. Any silver plating thickness, when averaged, that falls below the specified limit shall be considered noncompliant.
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