Shrinkage experiment

 

Shrinkage is one of the few dark spots on wool's otherwise stunning record. If you are not careful when you wash a woollen garment, it shrinks and the garment can no longer be worn because it is too small. Wool of course can be chemically treated to stop it from shrinking, but now an interesting experiment points to a different solution.

 

Laboratory tests have shown that, while untreated wool will usually shrink around 25% in the wash, some of the wool tested shrunk only 10%.

 

Dr Tony Schlink of the CSIRO in Western Australia and Dr Johan Greeff of Western Australia's Agriculture Department thought that a genetic factor may be involved in that wool which shrunk less. If there was, one could breed sheep which would produce wool fibres that were less likely to shrink.

 

But how can you easily tell if a sheep's wool is more or less likely to shrink? We usually only find out after we wash a garment. Our good doctors, however, devised a simple experiment to test wool shrinkage from raw wool. They decided to simulate the washing process in a tumble dryer. They took one gram of the raw wool that had been cleaned and carded to remove tangles, next they placed it in a small container along with 25 millilitres of water, then that was placed in the tumble dryer for 30 minutes. The tumbling action caused the gram of wool to form a tiny ball in its container. The process was repeated with wool from different sheep and the diameter of each ball of wool was compared. The wool that formed bigger balls obviously shrunk less.

 

Over five years they tested wool from 4000 sheep. Because they could now find the source of the wool, they could identify the characteristics of those sheep which produced the wool. This means that it is possible to select for breeding those sheep whose wool shrinks less, so that in the future all sheep will provide more shrink resistent wool and it will no longer need to be chemically treated.