Residual stains on table linen will spark justified customer complaints and the increased incidence of problem stains is a concern for the industry.
These are occurring on cotton items from un-removed proteins and on items containing polyester from proteins and from oily, greasy components.
The reasons why polyester can give more problems in stain removal are not well understood. As a consequence, there is more frustration than needs be. In practice, the solutions to both problems are well established but not always widely practised.
Although the change from cotton to polyester cotton produced few problems, increasing bleach was found to be ineffective in tackling oily stain residues.
The much bigger change from polycotton to 100% polyester was far more problematic. Users found that stains would come away from polyester items made by using continuous filament polyester for both warp and weft. This cheap and colourful fabric found widespread acceptance very rapidly and is now firmly established at the lower cost end of the market.
The change to 100% polyester items made using continuous filament yarn in one direction and spun filament yarns in the other direction was a bit more challenging, but detergent suppliers were able to meet requirements.
However, the advent of fully textured yarns using spun filament in both directions has presented launderers with even greater stain removal problems, particularly those caused by oil and grease. When customers started to hold every tablecloth up to the light, the stain shadows became obvious and relations between customer and textile renter soured rapidly.
This month’s article examines some of the common problems with stain removal, colour continuity and residual odours and how to tackle these.

Residual stains
Stains acquired in the restaurant (as opposed to stains from abuse in the kitchen) fall into three main groups:
Vegetable dye stains from tea, coffee and red wine and any colouring from something that originally grew in the ground. These stains come out very easily with a low dosage of bleach, provided that they have not been locked onto the cloth by old set protein stains.
Protein stains from gravy, meat juices, custard, ice cream and anything from an animal (such as milk and blood-based products). These stains need to be softened for 4-5 minutes with a little detergent (to wet the fabric) in a well-designed pre-wash. The key is to keep the pre-wash temperature in the range 35-40C; 38C is ideal.
Oily, greasy stains from olive oil, pumpkin oil, sunflower oil, eucalyptus oil, meat juices, butter, cream and a whole host of the chef’s favourite ingredients. These will come away from cotton with good detergency. They will only come away from polyester fibres with even more detergent or with the aid of the right emulsifier.
If protein stains pass through a pre-wash stage of above 40C, the temperature will cause them to set onto the fibres and they will become almost impossible to get off, even with the right temperature and mechanical action in the main wash. Some launderers will counter this by raising the alkalinity sufficiently in the main wash to chemically "burn" the protein off the fabric, but this alkalinity all has to be rinsed off the cloth or otherwise neutralised, so it is far from ideal.
There is no point in simply adding any emulsifier in order to break the very strong oleophilic bond, which holds a greasy stain onto polyester fibres. The emulsifier must have a hydrophilic-lipophilic balance (HLB value), which matches that of the greasy stain to be removed. It is unlikely that the emulsifier normally used for engineer’s workwear will work, because this will have an HLB value of around 15 or more. Kitchen oils tend to have an HLB value of 11 or even lower. The best emulsifiers for table linen will offer power over a range of HLB values.
The best way of checking the adequacy of a wash process for polycotton or 100% polyester is to check for residual oily stains either over a light table or against a bright window. Any oily, greasy residues will be show up immediately.

Colour continuity
It is not easy to maintain colour continuity over time when topping up rental stocks of coloured table line continually.
However, it does help enormously if the laundry keeps a reference set of colours against which it can order. With this, at least the supplier can try to match as closely as possible the colour of the latest delivery to that of the original consignment, which is a good start.
It is then necessary to check how the latest delivery is going to look after it has been washed four or five times. This should be done with a single item so that if there is a significant discrepancy with what is already in circulation, there is still time to send the batch back and ask for a replacement. The supplier will usually agree to this if the rest of the consignment is unopened and unwashed, because it can be sold to one of your less well-organised competitors. Washing coloured cotton and polyester cotton using the correct detergent will help colour continuity with items containing cotton, which means using a detergent free from optical brightening agents (OBAs). These ingredients of a standard white work detergent will react with the ultraviolet portion of the daylight spectrum and make coloured cotton fibres look prematurely faded.

Odours and bacteria
Bacteria will thrive on un-removed protein staining and on oily, greasy staining. When this happens in restaurant storage, the bacterial excrement exhibits a range of odours, all of them unpleasant.
Other micro-organisms may include fungal growths that thrive in dark, cold conditions with a little dampness to encourage reproductive growth. The odours from these tend to be dank rather than immediately offensive but tare just as undesirable, especially if accompanied by black, blue red and green mildew marks.
Young mildew can often be removed by strong bleaching. In a tunnel washer this means 6ml of 15% sodium hypochlorite as delivered per kg of dry fabric. However, if the mildew is deeply ingrained then an overnight steeping in a bath containing 150 parts per million bleach will be more effective. However, neither method will give 100% recovery and the older the mildew, the lower the recovery rate.
To tackle mildew effectively, first get the stain removal right and complete (so there is nothing to feed the growth) and then make sure that the dirty storage conditions do not permit growth to begin.

Correct starching for crisp cotton
The best cotton table linen is starched correctly to achieve the crisp result favoured by the top restaurants. This means buying a good quality starch and building this into the fabric, with a temperature of around 50C, a medium dip and at least four minutes in the starching bath. In a tunnel washer this may mean two starching pockets.
A short, lower-pressure squeeze in the membrane press will leave plenty of starch in the fabric but the excess moisture will then have to be removed in the tumble dryer.
Four minutes in the dryer should be sufficient to open out the edges to give the best chance of a perfect result in ironing, with no folding over of the leading edge and no side creases either.
If folding of the leading edge or leading corners is still a problem, then it is worth checking and if necessary maximising the vacuum. A strong vacuum in the range of 30-60 kPa is required to remove the water vapour and dry out the roll cladding, so that there is sufficient friction at the in-running nip to take the leading edge and corners cleanly into the bed. A single "stutter" at this point is all it takes for a fold or crease to form.

Avoiding greying of white linen
Cotton will grey if the suspending power of the pre-wash or main-wash is too low to prevent re-deposition of soiling from the wash liquor back onto the fabric. This is usually the result of insufficient detergent; occasionally it results from the use of a cheap detergent, which has too little suspending agent in the mix.
Greying will also occur if the tunnel washer has to wait for a tumble dryer to become free at any point before the table linen batch is discharged. The amount of greying is directly proportional to the length of the delay. The reason it occurs (even with the best detergents) is because there is only so long that a suspending agent can wrap around removed soiling and keep this in suspension. Sooner or later the suspension will fail and greying will occur.
The problem is even more acute with polyester fibres, which are much more difficult to recover once they have greyed in this way. The problem is made worse if the launderer relies on very high alkali or very high levels of bleaching (instead of good washing) for stain removal. This is because polyester is susceptible to both alkaline hydrolysis and acid hydrolysis, with consequent degradation of the fibre surface. This degradation gives the surface a permanently grey appearance from which it cannot be recovered. This is why polyester tends to give poorer whiteness results than pure cotton and why once it has gone grey it stays grey.

Higher output from the ironer
Table linen irons best if it is ironed slowly, to produce a flat, crease-free and firm result. There is no point in over-conditioning table linen in the dryer in order to permit faster calender speeds. This is expensive and it usually produces poorer quality.
It is far better to iron from a reasonable moisture content – of around 45% for cotton – and to aim to cover the entire ironer bed as far as is possible.
This enables good output to be maintained and pays large dividends in terms of quality. There is no point in feeding into an ironer at say 35m/min if the bed is only half covered. Running at half this speed with full coverage would give the same output with less time in the dryer and much higher quality.
There are more benefits from getting table linen processing right than just reducing customer complaints. With the correct methods, greying will reduce, textile life will increase and the deliveries will again smell fresh and sweet.
Re-wash will reduce, productivity will increase and energy costs will drop.


GREASE STAINS: Grease stains can be seen more clearly under ultraviolet light