MOISTURE IN WOOL

Te Puke Times, Volume XXXVI, Issue 21, 18 March 1947, Page 4

MOISTURE IN WOOL

INILEFACE ON SALES

PROBLEM OF OVER-DRYING

During ;m in vostipalioii of t lie possible causes of spontaneous combust ion in skin wools. Dr. I*. R. .McMahon, of the Wool .Melni' lopv Eahoatoi’V at Lincoln ColI(;■ c'(>, came to the conclusion that l(icr<' is a strong possibility that New Zealand annually pives away a p'ood deal of wool without receivinc' payment for it. Wool is by international usaire permitted to contain a certain amount of moisture. The amount of wafer allowed varies for certain types of wool, and varies also from country to country, hut it appears that most slipe ami scoured wool which is dried mechanically after processing is sold by New Zealand with less water in it than is permitted. Envers are unable to detect and pay a premium for drier wool.

“The total value of slipe and scoured wools is so ereat (approximately £8,0(10,000) that a small (vain of 2 or 8 per cent in efficiency ol marketine' can mean as much as £240,000, ultimately, to wool pi (Mincers,’’ Dr McMahon s report states. “The importance of this is enhanced by.the present move toward sellinjr these wools in New Zealand, instead of London with the consequent shorter time for over-dried word to pick up'its full weight of moisture. The report {foes on to discuss the difference between moisture content of wool, and “regain,” which is usually adopted by the wool trade. Refrain is the amount of water wool will take up from (lie atmosphere after if has been thoroughly dried. Wool will contain as much as one- third , f its we ip lit (repain B'B per .cent) of water without appearing wet, but tlio actual amount of water taken up by a pi veil wiuplit of wool depends on atmospheric conditions, and is hiphest when humidity i* hiph and temperature low. There is an appreciable difference depmidinp on whether the wool conies into equilibrium with the air after beinp dry or after beinp wetter than the air.

“It appeal's to be common practice in fellinoiiperies and seourinp works to over-dry wool sliphtly. allowinp it to condition in the bin for several days before pressinp. In view of tin 1 diflieulty which is experieneeil in condit ioninp small samples in a controlled humidity room where the air is in constant circulation, it seems likely that nnuch wool is pressed and weiphed for sale in an over-dry- state. Samples'of jto llh of wool, for example, r-estiiiff on a slotted ‘shelf with pood ■ air circtilatinp lake at least 48 hours to come to constant weipltt. A larpe hulk in a Ivin, even if loosely ]lacked., must take immeasurably loi.iper to eoiidition. Support for this conclusion is pi ven in an observation Iron) Mr R. V. IVryman of the New Zealand Mills’ Research Association (lue.). Me measured the repain of wool on the outside and from the interior of sheets contuiniup 2<d-8f)0lbs of scoured wool si aml inir under a verandah w here it would be protected from the rain. but. open to wind and dew. After several weeks, tlx* outside lave,- bad tin* expected moisture content while the interior was still over-dried. “It is clear from these results that there is considerable daiipeV of weiphinp wools for sale' ill an over-dried stale, with consequent loss to the vendor. This is all the more important since wool buyers are not able to disfiupuish small differences in repain and hence cannot pay a premium for overdried wool—a fact which was recognised during the war in Australia, where the (Icutral Wool Committee insisted on regain tests being curried out on all lines of scoured wool pint up for appraisal. It is worth nothing that the addition of f) per cent of moisture to 200,00011) of Avoid,, the normal dairy through-put for a large fellmongery, would involve approximately 100 gallons of water. Control at the drier, therefore, would appear to be the most efficient way, since il would give some saving in operating cost and at the same time increase 'the capacity of the unit.”