Softly® detergent

Softly was developed by CSIRO’s Tom Pressley in the 1960s in response to the claim by a British microbiologist that woollen blankets were a major source of infective, airborne particles because they couldn’t be laundered at high temperatures.

In the period 1958-68 Tom showed that the claim was without foundation, then went on to develop a shrink-proofing process that enabled woollen blankets to be washed at elevated temperatures. After repeated washing, however, the blankets became stiff and rough, so a special neutral detergent for washing woollen fabrics was developed.

The detergent was so successful that it was produced and marketed by the Unilever Corporation under the trade name Softly®. It has been on the worldwide market since the 1960s and is now manufactured by Pental, a subsidiary of Symex Holdings Limited.

Woollen blankets under attack

A letter published in 1957 in The Lancet caused a flurry in hospitals throughout the world. It claimed that because woollen blankets could not be laundered at the high temperatures (80ºC) used for other hospital textiles, they would harbour infectious agents which could be carried through the wards on fibres shed by the blankets. This report led to staff at the Royal Melbourne Hospital urging their Board to change to cotton blankets. The Chairman of the Board, however, contacted CSIRO seeking help as he realised the claim had serious implications for the Australian wool industry.

Unfounded claims

Tom Pressley at CSIRO’s Division of Protein Chemistry in Parkville undertook the task and showed the claim was without foundation. He collected dust at various levels in hospital wards and found that 96 per cent of the air-borne fibres in the hospital were cotton lint and that air-borne fibres in general were not major carriers of bacteria. Furthermore, because of the density of wool and its tendency to felt most of the wool fibres were below bed level. He then arranged a long-term study as a PhD student in collaboration with the Department of Bacteriology at Melbourne University, to determine the distribution of pathogenic bacteria in airborne particles and showed that fibres were not an important vehicle for bacteria.

Tom also worked with the Royal Melbourne Hospital Central Linen Service and initiated laundering tests in full scale machinery to determine the most durable fabric for institutional blankets. Single fibre blankets (wool, cotton, nylon and other synthetics) and mixed fibre blankets (wool-cotton, wool-nylon, cotton-nylon, etc) with various weaving modes were tested in this way.

How to sterilise woollen blankets

Work began on finding a way to sterilise woollen blankets. First it was necessary to devise a reliable shrink-proofing method for wool fabrics. Tom found that the notorious unreliability of dry chlorination as a shrink proofing procedure stemmed from the lack of control of regain (water content) in the wool before treatment. Tom had recently been involved in setting up the Wool Testing Authority in Melbourne and was expert in determining the water content of wool. He found that by ensuring the blanket material was conditioned to a predetermined regain before chlorination, consistently excellent shrink-proofing was achieved. The harshening of the wool by this procedure was offset by treatment with a cationic softener. Blankets treated in this way could be laundered in the hospital laundry at 80°C without shrinking.

On comparing the performance of the various blanket types in the laundry routine he then discovered that all woollen blankets far outlasted all competitors. Usually they survived 300 washes and still remained serviceable, whereas cotton and synthetic blankets rarely survived 150 washes. North Western Woollen Mills put the process into effect and supplied ‘all-wool’ blankets to hospitals throughout Victoria. It is no far-fetched statement to say that the woollen blanket industry was thereby rescued from probable oblivion, not only for hospital use, but also for general domestic use.

Softly is born

One other factor had yet to be resolved – the detergent. As blankets went through repeated hospital laundering they became stained and rough. The staining was due to iron in Melbourne’s water supply, and this was stopped with a chemical agent that attracted iron particles. To address the texture problem, Tom worked with a shovel to mix up batches of detergents on his laboratory floor to devise a detergent that would hold particles suspended in water but stay chemically neutral so the wool would not be damaged by boiling.

The end result was a pH neutral detergent that was so effective in the hospital laundry that the formula was taken up by the Unilever Corporation and marketed as Softly®. Softly® is still available on supermarket shelves today and is widely recommended to gently clean and soften wool, washable silks, fine cotton, linen and fine synthetics.

Other initiatives

Tom was to later use his expertise with hospital blankets, together with his skills in leather research, to develop medical sheepskins which could be laundered with the blankets. The experience gained from the production of medical sheepskins was later used in a collaboration with the Department of Surgery Melbourne University, to produce wool-based external mammary prostheses.

The Central Linen Service at the Royal Melbourne Hospital continued to use Tom Pressley as an in-house consultant and was rewarded with improved oils, wares and dusters for hospital use.

Source

• Rivett DE, Ward CW, Belkin LM, Ramshaw JAM, Wilshire JFK, 1996, The Lennox Legacy – A History of the CSIRO Laboratory at 343 Royal Parade Parkville, CSIRO Publishing, Melbourne, Australia, 370 pages.