BLUESTONE STAIN ON WOOL

Press, Volume LXXXIX, Issue 26971, 21 February 1953, Page 5

BLUESTONE STAIN ON WOOL

INSIDIOUS RESULT IN SOME CASES RESEARCH BY SCIENTISTS Research has been carried out on the concentrations of bluestone (sulphate of copper) that may be used in the treatment of sheep in relation to the effect on the wool. Very low concentrations as used in gammexane dips are permissible, and also high concentrations for foot-rot baths provided the wool does not get stained. Copper stains the wool, interferes with bleaching, and affects the shade of many of the faster dyes. Scientists of the New Zealand Woollen Mills’ Research Association (Incorporates), one of the six researcji associations that receive grants from the Department of Scientific and Industrial Research, have carried out extended tests on the effects of various concentrations of sulphate of cbpper on wool. It was found that the amount of copper retained in the wool from dips which included copper sulphate was but slowly reduced by weathering (after allowing for the growth of new wool). The various stages of processing were examined, laboratory tests were made of wools of different qualities and with various treatments, and a number of dyes that are affected by copper were studied. Recommendations Various recommendations have been made by the association. There is no justification, 1 says the information bureau of the Department of Scientific and Industrial Research, for stopping the use of copper sulphate in gammexane dips provided the present concentration of 0.03 per cent, is not exceeded. High concentrations for footrot baths, which are universally used, will stain the fleece unless the sheep are carefully handled so as to prevent splashing or the sheep falling in the troughs; these stains are prominent, however, and the affected wool can be taken out in sorting. The use of copper sulphate at a relatively low concentration of 0.2 per cent, for dipping against mycotic dermatitis has a more insidious result. The greasy wool may not be stained, so that the wool passes through the sale and the mill sorting-room unsuspected, and the presence of the copper is not detected until the dyer tries to dye it with a light shade of a sensitive chrome colour when obscure and annoying dyeing faults will arise, or in bleaching white the wool will be dingy. It is pointed out by the bureau that although the average copper content of the wool may not be very high the copper will, in fact, be concentrated towards the tip end. causing the tips to dye a different colour from the remainder instead of giving a general off-shade