QUALITY ASSURANCE TESTING
plating thickness white gold, colour measurement tarnishing

tarnashing

tarnashing, durability, hardness

Tarnishing is a problem that is unlikely to be completely eradicated. Industry is working hard to keep this to a minimum.

The laboratory has devised various in-house test methods for Tarnishing, Durability and Hardness. All tests have been developed from appropriate International Standards.

tarnish tests

TESTS RELATING TO TARNISHING AND SURFACE DURABILITY

TARNISH RESISTANCE TEST
The Tarnish Resistance Test combines methods from appropriate Standards to create one combined, cost effective test to determine whether an item is susceptible to tarnishing. The article is exposed to the most common accelerants of tarnishing encountered during packing, transport, storage, store display and during wear conditions. These are ultraviolet light, atmospheric oxygen, humidity, changes in moisture and temperature and synthetic perspiration. Results indicate the degree of tarnishing/deterioration that occurs.

NB: Sulphur has not been included in this list of accelerants - see Sulphurous Agent Test.

Turnaround: Results usually reported within 4-5 days.

Number of samples required: One article (randomly selected from a production lot).

SULPHUROUS AGENT TARNISH TEST
This test is appropriate for articles that have received special treatment (such as a protective coating, intended to minimise the effects of attack by sulphur bearing compounds), to test the effectiveness of the treatment. The test exposes the item to the three most common accelerants of tarnishing which may be encountered during packing, transport, storage and in store display. These are sulphur, humidity and temperature. An assessment is then made of the resistance to tarnishing.

Turnaround: Results usually reported within 2-3 days.

Number of samples required: One article (randomly selected from a production lot).

PACKAGING MATERIAL TESTING
This method covers the qualitative identification of the presence or absence of items used in the manufacture of packaging material that may tarnish or stain gold/silver/silver plated/unplated articles which come into contact with the packaging.

Turnaround: Results usually reported as a 'Pass' or 'Fail' only, within 3-4 days.

Number of samples required: One example for each type of packaging.

TEMPERATURE/HUMIDITY TEST
The surface/coatings of the sample are exposed to controlled conditions of humidity and temperature by heating and cooling them in a specially designed chamber. The degree of corrosion or deterioration of the coating and/or of the substrate is used to assess the level of resistance of the surface/coating to the test conditions.

Turnaround: Results usually reported within 3-4 days.

Number of samples required: One article

SYNTHETIC SWEAT/ PERSPIRATION TEST
This test determines the resistance of articles to prolonged contact with perspiration. Turnaround: Results usually reported within 3-4 days.
Number of samples required: Three articles:

ULTRAVIOLET LIGHT TEST (Sun Radiance/Humidity/Temperature)
The article is subjected to conditions of high humidity and temperature and exposed to UV rays for a period of 72 hours. Colour changes to the surface and surface appearance, as a result of exposure to UV rays are assessed, both by visual and spectrophotometric measurement, where possible. High quality photographs are also used for judgment purposes.

Turnaround: Results usually reported within 3-4 days.

Number of samples required: One article

POROSITY TEST This test gives an indication of the quality of the gold, rhodium or platinum coating on a base metal alloy. Its purpose is to highlight any corrosion of the base metal alloy in areas where there are inconsistencies in the surface coating.

Turnaround: Results usually reported within 3-4 days.

Number of samples required: One article (randomly selected from a production lot)

CHLORINATED AGENT TEST
This test simulates exposing gold/silver plated/unplated articles and watches to a swimming pool environment. Colour changes to the surface are assessed, both by visual and spectrophotometric measurement, where possible. High quality photographs are also used for judgment purposes.

Turnaround: Results usually reported within 3-4 days.

Number of samples required: One article (randomly selected from a production lot).

LEATHER/TEXTILE (FABRIC) TEST
This test determines the colour fastness to perspiration of leather/textiles of all kinds.

Turnaround: 2-3 days.

Number of samples required: One article

OTHER DURABILITY TESTS

STONE ADHESION
To assess whether stones in stone set articles are adequately set or glued to the setting by using a tape adhesion method and/or ultrasonic stone adhesion procedure.

Turnaround: Results usually reported within 2-3 days.

Number of samples required: Two articles.

HEAT TEST
Determines the reaction of articles to severe temperature changes. Articles are exposed to drastic fluctuations in temperature, then the surface is examined for signs of blistering or detachment under 10 x magnification.

Turnaround: Results usually reported within 2-3 days.

Number of samples required: Two articles

IMPACT DROP TEST
Establishes the resistance to adhesive failure during impact on stones (includes glass, plastic and metal posts and inserts) glued in the settings.

Turnaround: Results usually reported within 2-3 days.

Number of samples required: Three articles.

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