An Important Development in
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Rubber Seat Cushions
New Dunlop Material Made from Aerated "Froth." Substantial Economies in Weight Possible
ALTHOUGH sponge rubber has for soine time been well known as a material which can be used for seat cushions and other parts of the upholstery, certain novel features make -the latest Dunlop product particularly interesting. Instead of manufacturing a sponge from rubber which is already in the solid state, the latex is treated by patented processes which convert it into an aerated "froth." After the addition of a setting agent the "froth" is poured into suitable moulds wherein it sets and is later vulcanized.
For the material itself exceptional liveliness and recovery are claimed, as well as certain other important physical properties. By the use of moulds for shaping the article it is possible to produce, without difficulty, complicated forms, which may have internal webs, cavities, hollows, flanges and so on. It will be seen that, apart from the making of the mould, these offer no trouble. • The Dunlop seat cushions have vertical cavities extending upwards from the bottom surface and, whilst the lower part can be made of a comparatively dense sponge, the upper part may be
much softer so that it conforms readily? with the contours of the body. This result is achieved by filling the mouldin two stages with latex which has been " frothed " in unequal degrees.
One of the chief disadvantages of rubber has, in the past, been a lack of ventilation through the material itself, so that damp accumulates between the rubber and the covering material. Owing to the fact that Dunlop cellular air cushions, made by the Dunlop Rubber Co., Ltd., Fort Dunlop, Birmingham, have a porous surface, there is a continuous circulation of air due to the normal compression and expansion of the cushion when in use.
Although this material is comfortably soft and in a sense springy, it does itot cause any unpleasant bouncing and appears to have important self-damping Properties. There seems to be a'
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stantial saving in weight due largely to the cavitied construction. In the case of normal cuslaions this saving is said to amount to 40 or 50 per cent.