Just a cotton picking moment20 June 2017
There has been a recent resurgence in specification of 100% cotton for 4 and 5 star hotels. Richard Neale of LTC Worldwide explores the different laundering requirements for cotton and cotton rich linens and towels and the implications of the trend for the rental operator
The worldwide slowdown in growth over the last 10 years has seen pressure taken off cotton production capacity and a resurgence in demand for cotton versus cotton rich for hotel bed linen for the top end of the market. The selling features for the hotels have been breathability, moisture absorption and tactile comfort on the bed, aided by the soft, fine handle and texture of pure cotton in higher thread count constructions.
Executive housekeepers have noted that cotton fabrics stay white longer and if they do start to grey, then a good launderer can restore both whiteness and brightness to cotton, whereas once cotton-rich goes grey it is difficult to recover. Coupled with this are the natural features of a natural product, which makes cotton the natural choice on which to build a ‘green’ image.
The main advantages of cotton-rich (staying stronger for longer and being slightly cheaper and faster to launder) have not been able to reverse the trend to pure cotton at the top end of the market. This month we take a look at the key implications for the rental operator.
Cotton and cotton-rich should not be washed together, for very sound technical reasons. They have different detergency requirements, with cotton requiring mainly anionic ingredients, whereas cotton-rich needs plenty of non-ionic component to break the oleophilic bond between polyester and human body oils. Otherwise cotton-rich pillowcases quickly develop brownish discoloration in the central area where the head rests. Polyester fibres do not respond well to bleaching in the event of greying; the bleach simply degrades the polyester surface giving rise to further progressive and permanent greying. Cotton which has been discoloured by set protein soiling can be recovered using a process which incorporates an alkali-booster, whereas this might simply make the polyester fibres both weaker and greyer.
The load factor for pure cotton is 10 litres of cage capacity per kilogram of dry textiles in a washer extractor, whereas cotton-rich often requires up to 12 litres per kilogram. It can also need a cool-down if processed in a washer extractor, especially if the de-sizing during cloth finishing is incomplete (as revealed by irremovable cracked ice creasing).
The outcome of this is the need for separate classifications for cotton-rich and for pure cotton, which spoils one of the simplifying features of a modern high volume rental plant, assuming that the high-end renter is going to satisfy the demand for both products and wash them properly.
The moisture retention for cotton rich is lower than for pure cotton, which gives a valuable bonus in energy reduction and ironer speed. This is sometimes offset by the need for a slightly lower press pressure, to avoid pressure creasing which can be difficult to remove, especially if there is still manufacturer’s sizing in the cloth. However, both pure cotton and cotton-rich which have been well-made generally, benefit from the maximum press pressure for at least 30 seconds and preferably a full minute.
Tumble drying and ironing
Efficient de-watering enables tumble dryer times to be kept down to 30 seconds – just enough to break the ‘cheese’ of pressed textiles. This short time in the dryer applies to duvets also, even though their double thickness makes them more of a challenge in the ironer. This challenge is best addressed by feeding the covers edge to edge, running the ironer slowly enough to dry in one pass and then tuning the ironer to perform effectively. This means ensuring:
- no ‘cold spots’ on the beds,
- dry steam at the correct pressure,
- efficient drainage of condensate through the steam traps,
- good vacuum at the clothed surface of every roll (30-80Pa on the vacuum gauge),
- strongest vacuum to the front roll and
- good roll to bed fit (use the maker’s tapes to check).
The way to minimise drying energy both with pure cotton with cotton-rich is to use mainly the ironer and not the tumbler to evaporate the moisture. This is because the tumble dryer has a thermal efficiency of only around 55% whereas the ironer will usually approach 95%. The difference this makes over a working week can be very significant indeed, but in order to realise the energy and financial saving it is essential to learn how to tune the ironer and to keep it tuned. The average laundry ironer probably has an output of only around 60% of its design capacity and many laundries run with twice as many ironers as are really needed. Good engineering and sound understanding is called for here.
Cotton can be ironed with bed temperatures up to 200C, but this does not work for cotton-rich. The polyester fibres in the blend are progressively softened at temperatures above about 165C, which allows the fabric to stretch (when it loses the strengthening effect of the softening polyester). Unlike pure cotton, there is little or no recovery of cotton-rich which has been stretched in this way. It gets progressively longer in the machine direction and it ‘necks-in’ and becomes progressively shorter in the transverse direction. The consequence of this is that duvet covers ironed closed end first get longer and narrower (so that eventually the duvet will not fit). Sheets ironed widthways get wider and shorter, until they no longer fit the bed.
The best way to solve this expensive problem is to optimise the settings on the de-watering press to minimise the moisture content (including adjusting the ‘wait’ times in the computer control sequence if necessary) to gain the greatest possible time at full pressure. Then ensure that the ironer is serviced and tuned to do the work of drying and crease-removal whilst maintaining a reasonable speed. Ideally the laundry wants to be able to iron cotton-rich with a speed through the ironer that matches that achievable with pure cotton at 200C. This should be quite achievable with good engineering and a little maintenance effort. Under-sized rolls may need to be re-clothed, vacuum systems serviced, flattened springs replaced and water separators fitted, but these are largely one-off costs which have long-lasting benefits.
The secondary benefit from washing, de-watering and ironing both cotton and cotton-rich properly is the freeing up of tumble dryer time which this brings. Hotels are demanding heavier and larger towels, with more pile per square metre, and this is bringing with it a need for more tumbler capacity. There should be no need to embark on expensive additional dryers and the disruption which fitting these in can bring. Often all that is needed is a thoughtful approach to ironer optimisation, utilising capital that has already been laid out, by making the ironer do the work for which it was designed.
The demands of the market place will continue to pose challenges to the rental sector, but these can be met profitably with just a little thought and planning. This might call for greater co-operation between the laundry supervisor and the laundry engineer, whose roles continue to become greater and more complex. Customer delight, energy economy and profitable business are not mutually exclusive and the guidelines given here will hopefully be of help in achieving these.