Towel quality – the hallmark of a good laundry service11 July 2018
Following the principles set out in this article will help launderers to produce terry towels that stay white, are thick and fluffy and display no harshness or hardness, says Richard Neale of LTC Worldwide
Even the best four- and five-star hotels let themselves down when the guest enters the bathroom for the first time to be greeted by a pile of drab, grey towels. Even worse is a ‘zebra’ pile, with grey towels alternating with pristine new white ones.
Indeed, injecting new ones into the circulating stock can be counter-productive, because it really highlights the greyness of the rest. If the towels are spoiled by unsightly strings of yarn from pulled loops, the impression for the guest is even worse. Yet it does not need to be like this. The secrets of producing towels that are consistently white and always soft to the hand, with no strings, are not difficult to implement.
Why do towels go progressively greyer?
Towels tend to turn grey in both the washer and the tumble dryer. The problems in the wash have been very thoroughly addressed by the leading detergent suppliers, who usually incorporate enough suspending agent in their premium products to wrap around the ‘micelles’ of removed soiling, so that all of the dirt is flushed away to drain at the end of the wash stage and none is allowed to be re-deposited onto the textile. Greying in the wash is largely a thing of the past, although the chemicals supplier still bears the initial brunt of greying complaints (often unfairly).
The main problem is greying in the dryer, because unless the drying time is expertly controlled, half of all batches of towelling are slightly over-dried. Tumbling towels when they are effectively bone dry, even for a minute or two, generates a tiny electrostatic charge as the dry cotton pile rubs against the metal cage. This is sufficient to attract every dirt particle from the drying airstream onto the tips of the terry loops. This can best be seen under UV light, when the greying blocks out the fluorescence of the optical whitening agent on the fibres, magnifying the greyed appearance of the tips of the loops.
It is difficult to programme the dryer to yield a final moisture content of 2-4% every time, because incoming soiled towels carry varying amounts of moisture, making accurate weighing impossible. The best way of solving the problem is to fit automatic cycle terminators to every dryer used for towelling. This can be justified on energy saving grounds alone – the payback is usually under 12 months. A greater benefit is often the increase in dryer productivity and hence towel processing capacity, but the main benefit is the elimination of greying (providing the terminators are set up correctly – the residual moisture range of 2–4% is critical).
A commercial towel needs to be sufficiently robust to deliver up to 200-wash-and-use cycles without disintegrating or otherwise becoming a candidate for premature ragging. One common mode of failure for a poorly-made towel, often in the first few washes, is string formation. If the towel is snagged on a sharp toenail or a pair of nail scissors, then the security of the terry loop needs to be sufficient to resist the loop being extended to form a long ‘string’. This has now been recognised by international standards bodies and in 2008 a European Norm was published (EN 15598:2008) which described a standard method for determining the force needed to create extension by 1cm of the pile loop of a terry towel. Unfortunately, the standard does not specify the minimum force required for commercial adequacy, but it does at least allow a purchaser to specify a suitable minimum when measured by the standard method.
It has been found from experience that an extraction force greater than 3N gives a low level of stringing complaints, but some users demand a much higher retention performance, which is easily achievable with dense, short-pile constructions of the type used for bath mats. It is more difficult to achieve with softer, high-pile bath and hand towels and much more data is required. This is presently being gathered by LTC in an industrial research project and will be available for publication in due course.
When a towel shrinks in its first few washes, this tightens the weave and has two beneficial effects. The first is to improve the resistance to snagging by increasing significantly the force needed to create a string. This can often eliminate the risk of serial complaints from a new batch of towels and the first wash (before first issue to the user) is critical. This must use detergent and take the main wash up to the normal wash temperature for a soiled towel, in order to maximise the tightening effect and remove any residual spinning oils or yarn lubricants. If this is not done correctly, it can take up to five normal washes to achieve the same effect with a soiled towel. This is because a quick wet-out or low temperature wash with no detergent does not tighten the weave enough or remove the lubricants. When the towel is then dried, the elevated temperature will tend to set certain components of the yarn lubricants, making these exceptionally difficult to remove. Hence the need for five more washes to achieve what should have been done in one correct pre-wash.
Rather than specifying a maximum wash shrinkage when purchasing, it is preferable to specify a minimum size after washing (so that the circulating stock is essentially all the same size). Shrinkage of a new towel, in its initial wash before first issue, is a good thing in that it maximises resistance to snagging.
The average user requires a towel which is thick and ‘fluffy’ and soft to the touch. Many are disappointed, because launderers find it difficult to maintain the softness of a new towel. Although specifying a 2-ply pile yarn does improve the softness, this also increases the cost. An alternative approach is to improve the drying controls on the towel tumblers, so that no towel batch is over-dried or even allowed to become bone-dry. If the final moisture content is consistently in the range 2-4%, then the towels will be soft and ‘fluffy’ and they will also stay whiter for much longer. If there is a problem with ‘hardness’ caused by a towel not regaining its thickness after being compressed during de-watering, then delaying the start of heating for 30 seconds at the beginning of the drying cycle should correct this. It allows the terry loops to open out and float free in the drying airstream, before they encounter the blast of high temperature.
Complaints still occur from users of towels which shed appreciable lint early in their lives and then become visibly thinner and inferior, leading to premature ragging. The first indication of this is the frequency of lint-filter cleaning needed to keep the tumble dryers operating correctly. This problem occurs if the yarn spinner has used cotton with a fibre length distribution which includes a high percentage of fibres below 20mm. If the twist on the yarn is reduced in order to create a softer yarn for the pile (which it will do), then there comes a point where the twist is not adequate to hold the shorter fibres into the yarn structure. They become loosened by the mechanical action in tumbling and float off as loose lint. With less fibre in the yarn to hold it together and so even more fibre is lost after the next wash cycle and the towel becomes thinner and unusable.
By following the principles set out in this article it is possible to produce (consistently) terry towels which stay white, are thick and fluffy and display no harshness or hardness. With just a little care at the purchase stage it is possible to avoid the risk of string formation and deliver a towel product which will last for the critical 200 washes, unless it disappears earlier for other reasons (such as theft or abuse).
To contact LTC Worldwide please call
T: 00 44 (0) 01943 816545