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Heading 6401 : Waterproof footwear with outer soles and uppers of rubber or of plastics, the uppers of which are neither fixed to the sole nor assembled by stitching, riveting, nailing, screwing, plugging or similar processes.
This heading covers waterproof footwear with both the outer soles and the uppers (see General Explanatory Note, paragraphs (C) and (D)), of rubber (as defined in Note 1 to Chapter 40), plastics or textile material with an external layer of rubber or plastics being visible to the naked eye (see Note 3 (a) to this Chapter), provided the uppers are neither fixed to the sole nor assembled by the processes named in the heading.
The heading includes footwear constructed to protect against penetration by water or other liquids and would include, inter alia, certain snow-boots, galoshes, overshoes and ski-boots.
Footwear remains in this heading even if it is made partly of one and partly of another of the specified materials (e.g., the soles may be of rubber and the uppers of woven fabric with an external layer of plastics being visible to the naked eye; for the purpose of this provision no account should be taken of any resulting change of colour).
The heading covers, inter alia, footwear obtained by any of the processes described below :(1) Press moulding
In this process, a core, sometimes covered by a textile "sock" which later forms the lining of the article, is placed in a mould with either preforms or granules.
The mould is closed and placed between the platens of a press, which are heated to a high temperature.
Under the influence of the heat, the preforms or granules acquire a certain degree of viscosity and completely fill the space between the core and the walls of the mould; the excess material escapes through vents. The material then vulcanises (rubber) or gels (poly(vinyl chloride)).
When the moulding process is complete, the shoe is taken out of the mould and the core is removed. (2) Injection moulding
This process is similar to press moulding, except that the preforms or granules used in the press moulding process are replaced by a rubber-based or poly(vinyl chloride)-based mix, preheated to give it the viscosity required for injection into the mould. (3) Slush moulding
In this process, poly(vinyl chloride) or polystyrene paste is injected into a mould to form a complete coating which gels, excess material escaping through vents. (4) Rotational casting
This process is similar to slush moulding, except that the coating is formed by rotating the paste in a closed mould. (5) "Dip moulding"
In this process, a hot mould is dipped into the paste (this process is rarely used in the footwear industry). (6) Assembly by vulcanising
In this process, the raw material (usually rubber or thermoplastics) is prepared with sulphur powder and passed through a press to produce a flat sheet. The sheet is cut (and sometimes calendered) into the shape of the various parts of the outer sole and upper (i.e., vamps, quarters, counters, toe pieces, etc.). The parts are slightly heated to make the material tacky and are then assembled on a last, the shape of which conforms to the shape of the footwear. The assembled footwear is pressed against the last, so that the parts adhere to one another, and then vulcanised. Footwear obtained by this process is known in the trade as "built-up footwear". (7) Bonding and vulcanising
This process is used for moulding and vulcanising an outer sole and heel of rubber on a preassembled upper in one operation. The sole is firmly bonded to the upper with cement which hardens during vulcanisation. (8) High frequency welding
In this process, materials are bonded by heat and pressure, without the use of cement. (9) Cementing
In this process, soles which have been previously moulded or cut from a sheet are stuck to the uppers with an adhesive; pressure is applied, and the article is left to dry. Although pressure may be applied at a raised temperature, the material used for the sole is in its final form before the sole is stuck to the upper, and its physical qualities are in no way modified by this operation.
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