WHEN BUYING A RAINPROOF

Star (Christchurch), Issue 19108, 28 June 1930, Page 20 (Supplement)

WHEN BUYING A RAINPROOF

A rain-resisting cloth must be proofed and also of close weave. v So in the examination of rainproof fabrics two I tests are applied.

The first test is for “imbibition.” Ai weighed portion of fa.bric is completely! immersed in cold water for ten minu- 1 les. It is then ta v en out and allowed j to drain for fifteen m’nutes under I prescribed conditions, and then weighed. The percentage increase of weight j is a measure of the resistance to wet-! ting or degree of proofing.. An uprooted cloth will increase in

weight by about 200 per cent. A very well-proofed cloth may only increase in weight by 20 per cent.

The second test is the drop test. From a height of five feet drops of water are allowed to fall on to the cloth, alway's hitting the same spot. Underneath the cloth is a glass plate and between the plate and the cloth is a fine blooting paper. So soon as water penetrates a water-blot is seen on the paper.

If a rainproof cloth requires seven drops before penetration, it is good for ordinary purposes. A very' good rainproof may require seventy drops or more. A defective cloth may giva penetration on the first drop. Resistance to the drop test is secured by well-proofed cloth which is also of close weave. A raindrop is a sphere of very elastic fluid. •If the weave gave j a large mesh, the drop could pass right I through. In buying a raincoat one therefore ;requires good proofing and close weave. Ilf the fabric is not of sufficiently close [weave rain will get through in spite of the highest possible degree of proofing.