Quick Dips

Washing Wool

Researchers have been studying what makes wool dirty, and what remains to dull the fibres after industrial scouring processes. Not surprisingly, they have found the most common contaminant is mineral dirt, soil which is brought in on the wool from paddocks. What has surprised the researchers is the persistence of this mineral contamination.

"It remains on the fibre during the week-long scouring process," notes Margaret Leonard of the Wool Research Organisation of New Zealand. The agitation during scouring breaks up the soil into smaller and smaller particles, which are very difficult to remove once they are redeposited on the wool.

Even the material used for scouring presents a contamination problem. Under certain circumstances, iron sulphides can be produced in the liquids used to wash the wool, dulling the fibres' brightness. The reducing conditions in the scouring bowls cause sulphide, usually from residual pelt-removing depilatory paint, to react with iron in the mud and dirt initially on the wool.

It is this dulling of the body of the fibre that researchers are most keen to limit. Contaminants on the tip of the staple are less significant, as the tip is already discoloured from being exposed to sun, wind and rain. By finding ways of reducing dirt and iron sulphide deposits, researchers can help produce better quality wool selling for better prices.