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Skin Comfort Meter for Knitted Wool Fabric
Five commercial prototypes of the Wool Comfort Meter have been produced, to measure the next-to-skin comfort of woollen garments. One of the instruments was taken out of the CSIRO laboratory for the first time and given a public showing at a wool forum in Guyra, NSW in November, creating strong interest among producers.
A Comfort Meter was taken to Perth to measure the actual garments used in the extensive wool wearer trials being conducted there to measure actual consumer perception of the garments’ next-to-skin comfort. Good correlations were established between the Comfort Meter and the wearer trial results, demonstrating the promising accuracy of the instrument in objectively measuring next-to-skin wool comfort.
All remaining Comfort Meters have been moved from CSIRO to Deakin Uni where a fabric library will be established and a model for predicting next-to-skin comfort developed.
The fifth wearer trial is complete with 25 of the 50 participants being Chinese and the trial included two benchmark fabrics aiming at zero prickle. The fabrics for the 6th wearer trial have arrived at the garment maker in Perth and the next trial will start on time. The fabrics for the 7th trial are being manufactured by a major Shanghai knitter from yarns spun to CRC specification in Beijing.
The Garment Lab has also completed fabric handle tests, forearm prickle tests and a shortened wearer test protocol. Woollen test “sleeves”, manufactured in Perth, will be used in Albury for the new shortened wearer trial aimed at quickly gathering large amounts of data from wearers and using less fabric. The first 3-fabric trial using sleeves will was conducted in January to quantify the quality and accuracy of data from this source.
Recent measurements on a set of yarns prepared on a winding board, has demonstrated the ability of the Comfort Meter to supply meaningful data to predict the comfort of fabric knitted with those yarns. This opens up further applications for the Comfort Meter and will be pursued at Deakin University in 2010.
The commercial white wool trial has moved on quickly with the specially selected white wool yarn knitted at Levana in New Zealand and ready for finishing and garment making. The woollen yarn is clearly whiter than has been previously seen.
The fabric has been treated with ZnO and a doped ZNO-SiO2 in a nano form. The latter has been shown to have a significant effect on reducing photoyellowing of fabric. Further work will continue this year to quantify and improve the effect. Also work will continue to improve the durability of the treatment and reduce the effect on handle.
50 woollen fabrics measured for handle characteristics by the Phabrometer instrument have been assessed by four people experienced in fabric handle. Initial analysis indicates that fabric softness is related to specific Phabrometer test results, showing positive indication of the instrument’s ability to measure handle as experienced by people.
To date, fibre diameter and fibre curvature have been the only objective wool characteristics available to differentiate wool handle. A reliable Felt Ball Diameter (FBD) test has now been developed as a means of differentiating INF samples on wool handle characteristics. These results may be related to the handle of the greasy wool through the fibre scale height and spacing.
Early visual analysis of the Phabrometer results of a set of decatised fabrics shows the Phabrometer curves have a consistently higher, sharper peak for the decatised fabrics compared to the undecatised samples, again demonstrating the instrument’s potential for measuring this handle characteristic.
In an attempt to predict scoured wool colour prior to scouring, Near Infrared (NIR) spectroscopy scans were conducted on greasy wool from the 2007 drop INF progeny. This prediction of scoured wool colour is only moderate (35% accurate) and probably not viable as a test method.
However the NIR scans have proven to be very accurate for predicting residual grease following scouring (>90% accurate) and is being evaluated by AWTA as a test method. This is an unexpected but exciting outcome for the program.
To determine potential causes of wool yellowing at the producer end, wool samples from individual sheep selected for extremes in scoured wool colour from the INFs (2007 drop) have been measured. The samples were analysed for suint content, suint pH, suint mineral content and total wool minerals. Differences were apparent in suint pH and suint K levels. Models for their role in wool yellowness are being developed.
It is thought that certain bacteria on the skin of sheep may be a cause of wool yellowing. The role of skin microbial populations on base wool colour is being examined on 20 sheep from the INF showing extreme colour differences. These animals are being treated with antibiotics designed to knock out specific populations of resident bacteria from the skin. As heritability of colour is only moderate a non-genetic intervention may prove successful in producing whiter wool.
Benefits to industry
With wool’s share of the traditional Autumn/Winter mid-outer layer knitwear market in decline, a critical challenge is to create product opportunities in the emergent market of lighter weight, trans-seasonal, next-to-skin capable wool apparel.
Australia is the dominant producer of fine Merino wool suited to the production of lightweight apparel. With garment manufacturers able to access Australian Merino fabric of sufficient whiteness, photostability, handle and next-to-skin comfort, wool’s natural moisture and thermal management properties will give significant product advantages in this emerging market.
Results will include:
- A larger and more certain market for fine Merino wool
- Whiter, more photostable wool, reducing the need to apply conventional oxidative bleaches and increasing the competitiveness of wool in the Spring/Summer market
- Greater genetic and management control enabling growers to better meet market requirements for comfort and colour
- Increased buyer security for processors, retailers and consumers through the ability to assure quality for handle and comfort
CJ Hawkins Homestead, University of New England, Armidale NSW 2351