Secure couture
Production expectation
Turning merino wool into a functional safety fabric begins with wool preparation. This involves subjecting the fibre to a number of processes. Firstly, scouring cleans the wool to remove impurities such as foreign plant or vegetable matter and dirt, then carding breaks up the clumps of fibres to ensure they are uniform. Once these processes are complete, the wool is consolidated into a sliver or loose rope of wool.
The sliver is fed into the knitting machine at the same time as the synthetic Vectran fibre and the two components are fused together with latch needles. The machine has several hundred of these which rise and fall as the knitting machine rotates. Eventually the fabric emerges as a big tube or sock with a 1.5-metre circumference.
At this point the fabric is subject to a finishing process. The exact details are commercially sensitive, but the process helps to stabilise the fabric and give it the final dimensions and surface characteristics that are crucial to its stab-proof properties.
"The finishing process changes the fabric's structure to improve its strength and secures the fibres so they are less likely to come apart if it is attacked," says Mr Collie.
The knitting machine can also vary the knit structure by changing the simple base loop to alter the materials extensibility and the ease with which it deforms. As a result, the structure can be tightened to improve penetration resistance.
The biggest production challenge is the strength of the material. The yarns are so strong they can break the steel knitting needles. To overcome this, the yarns have to be knitted at as low a tension as possible.
The finishing process also acts as a general tidy up of the fabric surface, which may appear irregular, and eliminates any dirt that the fabric may have picked up from the processing equipment. Once the fabric has been manufactured, garments are cut to shape using special tools designed to cope with fabrics made not to be cut.
Initial plans are to produce 20-metre trial lengths of the material with production funded internally, but AgResearch is looking for a commercial partner to step production up to higher volumes. It is hoped the first phase of commercial production will remain in New Zealand, with AgResearch having the only knitting machine of its type in Australasia, which is capable of producing 20-30 metres of material per hour.
