MICROBES HELP TO MAKE WOOL HEAT

Press, Volume CII, Issue 30146, 1 June 1963, Page 17

MICROBES HELP TO MAKE WOOL HEAT

While replacement of the pie process in removing wool from the legs and necks of sheep by the slipemaster machine, which takes the wool off mechanically, had .largely eliminated beating of wool to combustion, low-tem-perature heating up to 70 degrees Centigrade did still occur if this wool was inadequately dried, Dr. M. H. Dye, of the Plant Diseases Division of the Department of Scientific and Industrial Research, said in Christchurch.

Dr. Dye said that 15 per cent, of New Zealand's total wool exports consisted of wool from the skins of sheep that had been slaughtered. The bulk of this wool was removed from the skin by use of a depilatory paint that resulted in a loosening of the wool which was then pulled off by hand. This wool was dried in spin driers after the removal process in which some water was used, but because of its high alkalinity it did not heat to any extent. It was not easy to put the depilatory paint on the leg and neck areas so the wool on these parts was now removed by the slipemaster machine. This wool amounted to lj per cent, of total exports. In earlier times, this wool —known as pie wool—had been rotted off by bacterial action and it had caused fires and for this reason the slipemaster process had been introduced. However slipemaster wool was still the main type of wool likely to heat. If these wools were inadequately dried they were capable of supporting microbes which could cause heating up to 70 degrees Centigrade. One of the main requirements for heating was the right level of acidity and alkalinity in the wool. The microbes grew on extraneous

matter in the wool «uch as dirt, plant seeds, straw, faecal matter, pieces of skin in slipe wool and possibly fat. Heating could thus be controlled by adequate drying to keep moisture so low that microbes were not able to grow or by better methods of eliminating extraneous matter on which microbes could feed. Heating of wool was certainly undesirable, said Dr. Dye, for as a protein it was liable to suffer degradation. Dr. Dye is working on heating of wool with Dr. P. R. Rothbaun, of the Dominion Laboratory of the Department of Scientific and Industrial Research at Petone.