Thanks, Bryan! Right, second instalment: The Russian National Standard for fins, which dates from the Soviet era:
2. Standards Publishing House (1977) Межгосударственный Стандарт ГОСТ 22469—77. Ласты резиновые для плавания. Общие технические условия
. Moscow: ИПК Издательство стандартов. The full text of the Standard can be found without cost as GIF images at http://vsegost.com/Catalog/81/8131.shtml
This 1977 Soviet, and now Russian, International Standard, subtitled with the official English translation "Swimming rubber flippers. General specifications", remains in force to this day. It is 7 pages in length. Its specifications continue to be applied to rubber swimming fins made in Russia and Ukraine.
Types, basic parameters and dimensions:
A rubber fin should consist of a blade and a foot pocket. Type A rubber fins have shoe-like foot pockets, while Type B fins come with straps and other fixtures. Fins should be produced to fit foot sizes from 26 to 47 in European sizing and from 165 to 305 in Metric sizing (millimetres). Each pair of rubber fins must have a size range corresponding to three adjacent shoe sizes (e.g. Metric 165-175 corresponding to EU 26-28).
Fins must meet certain requirements for tensile strength (strap only), hardness (blade minimum 60, shoe maximum 45, strap maximum 45), elastic rebound (38%), maximum change in hardness during ageing in air (5%) and maximum change in mass after exposure to sea water (2%). Fins should have a density of 0.95 to 1.30 g/cm³. The rubber compound used to make the fins must be approved by the Ministry of Health. The fins must be made either in a single colour, two contrasting colours or in marbled colours. Single-colour and contrasting-colour fins allow mismatch without adversely affecting the appearance of the product. A maximum figure is set for defect tolerance, namely surface bubbles, cavities and indentations, sharp edges, projections and burrs after trimming.
Covers quality assurance procedures, including frequency and randomness of product sampling, for evaluating hardness, rebound elasticity, tensile strength and material density.
Visual checks of fins for defects, which are measured with a ruler and a caliper. Visual checks of sizing, labelling and packaging. Tests conducted for hardness, rebound elasticity, change in hardness during ageing in air and change in mass after exposure to sea water. A device was proposed to test the rebound elasticity of a fin blade:
Marking. Packaging. Transportation and storage:
Fins are to be embossed with the manufacturer's trademark, the product name, the size and the name of this Standard, while a technical control stamp is to be applied to the rubber fins with indelible ink to mark the date of manufacture (quarter, year). The packaging is to be marked with the following information: name and trademark of the manufacturer; name of the fins; size of the fins; number of pairs of fins; manufacturing date (quarter, year); designation of this standard. Each pair of fins is to be wrapped in paper or placed in a polythene bag or in boxes and then packed in wooden crates, or cardboard boxes, gross weight not exceeding 40 kg. In city traffic, fins should be transported in cardboard boxes, with every four boxes wrapped in a strip of cardboard and tied with twine. Crates with fins are to be stacked on a flat tray. Rubber fins may be carried in any kind of covered vehicle. Rubber fins should be kept packed in a room where the temperature is between 0 and 25ºC at a minimum distance of 1 m from any heat-emitting devices and should not be exposed to sunlight, oil, gasoline, and other substances that deplete rubber.
The manufacturer shall ensure that fins comply with this standard, including the conditions of transportation and storage. The warranty period for rubber fins shall be one year from the date of sale to the retail network, and in the case of non-market consumption, from the customer taking delivery of the product.
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