GAS-MASKS MADE LOCALLY

Press, Volume LXXVIII, Issue 23587, 14 March 1942, Page 6

GAS-MASKS MADE LOCALLY

QUARTER MILLION FOR CIVILIANS WORK IN CITY FACTORIES A quarter of a million gas masks for civilians are being made in Christchurch by order of the Government. The processes in the manufacture of these masks, which consist of a canister with activated charcoal filter and a fitting rubber face-piece, were demonstrated in Christchurch yesterday when the Mayor (Mr E. H. Andrews), accompanied a reporter and photographer of “The Press” on a tour of the factories concerned. Raw rubber has been imported to New Zealand until recently in two forms, smoked sheet rubber, treated by a smoking process to preserve it, and crepe rubber, preserved by chemical processes. The crepe rubber is the more expensive of the two kinds and is generally used for light coloured goods, as the dark smoked rubber would require the addition of too much colouring material to bring it to a light shade; otherwise the two types of raw rubber are interchangeable. The first process in the manufacture of the rubber parts of the gas masks is the mixing, by pressure through large rollers, of the raw rubber with the appropriate chemicals to make the finished product have the required properties of elasticity and durability. According to the chemicals used for various goods, their finished rubber content ranges from 10-25 per cent, fpr some floor-coverings and garden hoses to as much as 95 per cent, in rubber bands used in shops. After thorough mixing the raw rubber in matted lumps it goes through another set of rollers to be pressed and heated into plasticity until it is fit to be rolled into the required thickness by a third set of rollers. From this third machine it emerges in a spool, carefully wound with a lining of smooth material to prevent the rubber from sticking. > The fourth process is the cutting of the patterns by machine; these are then vulcanised or cured at a high temperature. The face of the gas mask, all rubber, appears in one piece ready for sealing at the seams and with a space into which a celluloid window is fitted. Most of the finishing work to the masks is done by hand. All seams are sealed with plastic rubber cement and are then machine-sewn. The edges of the celluloid windows are bound with adhesive tape and the edges of the window spaces in the masks are bound also with adhesive tape, securely stuck with plastic rubber cement. The windows are then sewn by machine to the masks in such a way that' the masks will be completely airtight at the seams. The metal canister, also made .locally, over which the mouth of the 'rubber mask fits, is filled with layers of raw cotton and cotton wool to filter all dust out of air breathed in and with specially activated charcoal made from coconut shell and treated in such a way that it will purify air that passes through it, removing all poisonous gas A valve fitted in the mouth of the canister permits the wearer lo inhale, but prevents the exhaling of used air back into the charcoal. Exhaled air passes out at the sides of the mask, which automatically clings tightly to the face by suction action when the wearer inhales. The charcoal, which will be supplied for the masks by the Government, is prepared by the Christchurch Gas Company, said the Mayor. The canisters of the masks may be recharged with new charcoal from time to time. i Tar and Feathers I Tar and feathers were liberally i smeared over the entire frontage of 1 business premises in Greymouth in the i early hours of yesterday morning, toi gether with tarred letters over a foot I m diameter, referring to a certain ■ much-discussed attitude to military 1 service. Some hours of work were re- | quired to clean the windows and double doors of the shop, which occupies a prominent position in the business area. The incident, which is the first of its kind in the district, is the subject of considerable comment, and it is believed that the police are Investigating the matter.—P.S.S.