Troubleshooting laundering problems

OLD FAULT: Yellowing of new white linen, caused by textiles with an alkali- or chlorine-retentive finish, is an old fault which is re-appearing (pictured)

Life does not get any easier but a great many laundering problems have been solved over the past five years and this month we bring together some of the most useful solutions. The problems range from user abuse to premature failure of items before their design number of wash and use cycles, to ruination of items by incorrect laundering, to disappointment and complaint caused by incomplete textile purchase specifications and so on. The one factor they have in common is that they all increase costs and decrease already tight margins if not addressed and corrected. Taken together, they emphasise the wide range of knowledge needed by the modern laundry manager, struggling to make a profit from textile rental.

Patterns of small holes caused by incorrect membrane press settings

The modern membrane-press is a vital link in assuring profitable laundering, because when it is correctly tuned it rapidly minimises the moisture content of every batch after rinsing, thereby maximising ironer and tumble dryer productivity and minimising drying energy consumption. There is always a temptation to use the fastest ramp up to full pressure, in order to gain the benefit of maximum time at pressure and therefore minimum moisture retention going forward. However, some fabrics cannot tolerate the forces involved in the fastest ramp up to full pressure and when this happens, they burst and produce a characteristic pattern of tiny holes, all within a handspan of about 25cm. Most towelling is not affected, and the press pressure can safely be increased quickly. Problems can arise with high thread count, 100% cotton sheeting, especially when brand new (because the residual sizing can make it less porous, so that slugs of water become trapped, leading to a burst). All fabrics become weaker with age, so press bursts can dictate end of life, often prematurely. In order to maximise textile life for each classification, it is important to keep an eye on your rag analysis and if these characteristic burst patterns start to appear, then you should immediately reduce slightly the speed of the ramp up to pressure for the affected classification.

Yellowing caused by an alkali-retentive or chlorine retentive textile finish

Global supply chains, seeking to satisfy rental market demand for new textiles at minimum cost, are sourcing product from an ever-wider pool of international suppliers, large and small. One consequence is the re-emergence of problems which were thought to have been permanently solved years ago. A typical example is the unsightly yellowing of new textiles (both towelling and sheeting products) during the first wash. The yellowing deepens during the next wash and bleaching is ineffective. The cause is incorrect textile finishing following manufacture. If the cloth is left, by the finisher, with an alkaline surface (or one which retains alkali) and if this cannot be rinsed from it, then the fabric will yellow with the heat in tumble drying or ironing. The same effect occurs if the fabric has a chlorine retentive characteristic, because as soon as it encounters chlorine bleach then it will yellow when it is dried or ironed. Shrewd buyers are again including proper textile finishing in their purchase specifications.

Greying of towels in drying, rather than in washing

For many years it was believed that greying of towels occurred in the wash and was an inevitable consequence of age. Then market leaders, with strong help from their chemicals’ suppliers, devised a technique for measuring the amount of greying in washing and the amount in drying separately. This led to the adoption of a new test piece consisting of one new towel tightly folded into a small net bag and a second towel stitched to the same net bag at one corner, so that it floats freely during washing and drying. The test piece is then washed 25 times in the target towel process. The folded towel in the net bag (which will never have got dry in the tumbler process) is then taken out and dried off-line.

The colour of the two towels is then compared with the colour of a brand new, unwashed towel. The folded towel will display greying which has occurred only in the wash. The loose towel will display greying from both washing and drying. A significant amount of greying in drying is now believed to arise from occasional over-drying, which occurs with every towel classification from time to time. Tumbling a bone-dry towel will create a tiny static charge on the tips of the terry loops, which is sufficient to attract every dirt particle from the drying air stream and hold it securely.

The solution is to fit every towel tumbler with an automatic terminator, which halts the process when there is about 2% moisture left in the textiles. Although these are sold on the (justified) claim that they pay for themselves with the energy saved, they can be just as valuable for reducing greying and raising dryer productivity. They need to be set up carefully and kept clean.

Distortion and creasing caused by seriously ‘non-square’ weaves

The ideal weave for rental sheeting would have the same number of warp threads per inch or cm as weft threads – that is to say it has been woven ‘square’. The ideal 200 thread-count percale sheet would be a 100 x 100, but in practice it is difficult to make this, and the best rental sheets are probably woven as 110 warp threads/inch and 90 weft threads, which is also slightly cheaper. It would be cheaper still to weave the sheet as 150 x 50 (and it could still be legitimately termed a percale), but this would not look or perform as well as the 110 x 90.

This is because the more ‘out of square’ the fabric is woven, the more unstable it will be going through the laundry ironer and hence the poorer the finish achievable. A duvet cover might be offered to the customer as say a 200 thread count percale, at a special bargain price. If the low price is achieved by using a cheap 150 x 50 weave, then it is unlikely to be a bargain if it proves a nightmare to iron.

Symptoms of bag drag with which to face the customer

The best four- and five-star establishments in the London hotel market rightly demand quality and service from their rental providers and they usually get this. It is therefore very disturbing to find many of them daily abusing their sheeting stock and shortening textile life, with the net result that the rental service they get can never be profitable.

One of the biggest problems is ‘bag-drag’ – that is the use of pillowcases and duvet covers as linen bags in which used and soiled linen is transported from the guest room being serviced. When the ‘bag’ is dragged down the corridor it suffers surface abrasion and grit pick-up from the carpet.

When it is dragged over a linoleum floor en route to the soiled linen collection area, greasy grime is added to this. When it is dragged over door strips, holes appear wherever the ‘bag’ fouls a screw head or a sharp raised surface. The net result is a damaged area where the ‘bag’ has contacted the floor, which is scored with parallel lines of surface damage, interspersed with tiny holes and snag loops. Some hotels manage to ruin multiple duvet covers every day of the week, unless this is brought to their attention and stopped. Customer service teams are not adept at dealing with this, because they do not want to upset a major customer, but this customer is of no real value if the practice cannot be terminated.

Low tear strength after just two or three washes

There are many batches of fine, well-woven 400 thread-count 100% cotton bed linen, which drape well, feel soft and look superb on the bed. However, a 400 thread-count fabric in cotton will usually have a relatively low tear strength when compared with 200 thread count fabric of similar weight. The solution is to use good quality threads in the weaving, so that when the high thread-count fabric is torn in both directions, each thread has sufficient strength to offset the fineness and the result is just about good enough for an economic rental life.

Some batches of fabric in circulation have achieved a high tear strength using poor quality threads, by applying a soft linking finish, so that when the fabric is torn, each thread is supported by those on either side, giving a much stronger result. This is fine, provided that the finish is durable and will survive and function for 200 rental washes, before weakening. Unfortunately, this is not always the case and several batches of material have been sold into the rental market with good initial tear resistance, until after the second or third wash, when the tear strength is found to drop by over 60%! Beware!

Incorrect make-up of pillowcases and duvet covers

Rental duvet covers and pillowcases are usually best designed to be laundered closed end first, so that the tension through the ironer is in the length direction. Generally, the strongest direction with the least elasticity is the one in line with the warp threads, because fabric is woven with the warp under very high tension. There is usually twice as much elasticity in the weft direction, which means that there may well be much more distortion if ironed with the weft threads parallel to the direction of travel through the ironer.

This does not always make for economic manufacture, especially of duvet covers for delivery as singles through to super-kings. The easiest way to make these from one batch of woven cloth is to make the fabric width equal to the desired length of all the duvet covers and then make them all with the weft in the length.

A good supplier will minimise this problem by using fabric which is as ‘square’ a weave as possible, woven with strong threads with reduced inherent elasticity. Far more of a problem is posed by the pillowcase maker who makes a batch up with the weft in the length in order to get the best fabric utilisation with minimum off-cuts. When the unsuspecting launderer gets these, they will find that they will distort twice as much as the equivalent made with the warp in the length. The mock Oxford construction will be even more problematic.

Conclusion

Most of the problems described this month have now been successfully solved or minimised, but a casual walk around any laundry will still reveal the extent to which they still persist.