Fault analysis: recognise problems and allocate responsibility – 1

Margins are tight and when problems arise with faults that are unacceptable to the ultimate customer (the user of the textiles), then the client relationship can become stressed because no-one wants to take financial responsibility. The situation becomes worse when the hotel, hospital or restaurant staff demand that the fault is sorted out by the laundry, at the laundry’s expense. When the conflict escalates to imminent cancellation of the laundry or rental contract, it is not surprising that the laundry management accept the rectification cost. This is often unfair if the customer themselves, or the textile supplier, are to blame, but in the absence of evidence it is not that surprising. However, to accept the blame when it is not the laundry’s fault can set an unfortunate precedent, resulting in serial offences.

We look at the symptoms of some common and less common problems, which could empower customer care leaders with the essential tools to argue the laundry’s corner as they strive for a fair outcome.

Tiny holes suddenly start to appear in the circulating stock

The continuing trend to percale linen, which has established the standard for reputable four- and five-star hotels, means that problems in the first few washes still occasionally manifest themselves in the membrane press. There are still in circulation textile sizings (put onto the warp yarns in textile manufacture) which will not come off in the pre-wash before first issue, or even in the first five normal washes. As a result, there is a great risk of a slug of water in the rinse getting trapped in a fold of impermeable textile when it goes into the membrane press for de-watering. Now the key to low energy consumption and high productivity at the ironer lies in rapid and complete de-watering in the membrane press. This in turn calls for rapid rise to pressure, to squeeze out as much water as possible within the CBTW stage time of perhaps two minutes. As a consequence, young percale can come under pressures of 40-50bar, which are more than sufficient to burst an impermeable fabric when a slug of incompressible water is encountered. The result is a pattern of single thread breaks within an area covered by a hand-span, leading to 5–10 tiny holes.

The immediate solution is to improve the pre-wash before first issue so that it removes the sizing and improves the permeability of the cloth sufficiently for membrane press bursts not to occur. This is so important that external help from the detergent supplier or other specialist supplier should be sought if the problem continues.

The long-term solution is always to specify new textiles which have been fully de-sized in textile finishing. This should not increase the cost of the textiles (leading suppliers already ensure thorough de-sizing), because the unwanted size (which is essential for economic weaving) comes off easily in finishing, if this is done before final heat-setting in the finisher’s stenter. A check can be made for correct de-sizing, by the water droplet test on incoming fresh stock. Remove one sheet or one pillowcase from the new batch, and place one droplet of tap water on it. A sheet which has been fully de-sized will absorb the water droplet within a few seconds. If the textile has had a textile finish applied to it to enhance the appearance, then the new sample should be given a normal wash, before the droplet test is performed.

The same pattern of tiny holes can appear during dewatering in the membrane press, if the circulating stock has been prematurely weakened by bleaching (less common these days with modern detergent systems). This is generally more of a problem when using sodium hypochlorite (rather than hydrogen peroxide or other modern replacements), because it is often tempting to overdose this inexpensive bleach, in an attempt to improve stain removal. This results in rapid weaking of the textile stock, followed by holes and tears (not only in the membrane press) and the need for rapid replacements. The problem with sodium hypochlorite is that if any gets into liquors above 50C, then degradation of the cotton starts to occur, even at nominally safe dosages! This can occur in a tunnel washer, if the bleach is not totally used up before recirculation of rinse water into the hot wash.

Loss of pile

The appearance of small ‘bald’ areas, just on one side of the towel, can be a very puzzling problem for laundry staff. Hand towels and pillowcases make very handy cleaning cloths for the room service staff, who may frequently make use of them for wiping down bathroom ceramics and mirrors. Ceramic cleaners tend to be either acidic or they contain strong oxidising agents, which will quickly strip the pile off one side of a terry towel after a single misuse. Damage from ceramic cleaners is terminal and the towels with bald areas should be scrapped and the customer charged for the replacements. If a cage of soiled towels is checked with the appropriate abuse-indicator, it has sometimes been found that 30-40% of the hand towels in a soiled return load are affected in this way!

Holes in pillowcase fabric

Random shaped holes can be caused during room cleaning by a splash of bathroom cleaner containing sodium hypochlorite (chlorine bleach) as well as by an acidic ceramic cleaner. Although chlorine bleach can be used quite effectively in a laundering process, at concentrations of around 150 parts per million (ppm), a bathroom or kitchen cleaner containing bleach will often have several thousand ppm. A splash of this on a used pillowcase will rot a small area of cotton fabric, so that when it is next washed the rotted material will come away to leave a random shaped hole.

With a sheet made from a polyestercotton fabric such as cotton-rich, the effect of bleaching is to slowly weaken and remove the cotton component, leaving the polyester undamaged. The resulting ‘hole’ now has clear and distinct edges, but the central area is covered with a very thin translucent skein of loosely spun polyester staple fibres, which are not attacked by hypochlorite.

Identifying iron correctly

Iron can be a serious problem for the launderer from two sources: iron in the raw water and iron oxide staining on the textiles (which does not wash out). Iron in the raw water causes damage to the water softening resin, when some of the contamination progressively poisons the resin, shortening periods between regeneration and reducing the longterm life of the resin. It also builds up as minute traces of iron oxide on the textiles, causing progressive greying. If sodium hypochlorite is being used for bleaching, iron can catalyse (accelerate) the progressive degradation of cotton fibres, significantly reducing linen life.

Iron in the raw water needs to be measured accurately in a laboratory using the appropriate colourimeter, because the upper limit for safe laundering is only 0.1ppm.

Iron staining can be rapidly recognised

Iron and other metal staining can be differentiated from other contaminants by examination under UV light. The parts of the stain containing a metal or metallic compound fluoresce towards black, as is clearly shown by the small very dark areas around the edge of what is probably a protein stain. A good rewash might improve the protein marking, but recovering the entire textile to white will require an iron recovery process.

Iron staining on textiles needs to be identified using either a chemical test or using ultraviolet light. Identification of iron staining is important, because it needs to be identified at source (and the source removed). Rusty drips from air conditioning units are a common source and the cure is usually repositioning the soiled textiles storage area. Yellow brown marking on textiles could be oxidised protein or it could be rust and it is important to know which, because the recovery processes are entirely different – a laundry rewash process will not work!

All over pilling or bobbling

The appearance of pills (tiny balls of tangled fibres) all over a sheet or pillowcase ruins the appearance and leads to justified complaints. With a magnifying glass first check if the pills are coming from the textile of attaching to the textile.

If it’s the latter in a tunnel washer, check the lint filters are working effectively. If it’s the former, this can be a yarn issue, which arises because the mechanical action in laundering (or in use on the bed) rubs the short staple fibres out of the yarns. This creates a ‘hairy’ surface on the fabric and when the fibres agglomerate to form tiny balls of lint, these are termed ‘pills’.

The fault arises because the twist on the yarns is inadequate to hold the short staple fibres into the yarn structure. The fault is unlikely to be detected on delivery, but it will usually appear within a few washes and the supplier should then be notified promptly. The fault cannot be cured by the launderer.

The faults are avoided either by using cotton with a lower percentage of very short fibres (which makes the yarn more expensive) or by increasing the twist (or changing the method of twist)

Conclusion

This review of common problems will conclude in the next (September) issue of Material Solutions.