Modern textiles will require greater care

Cotton has been the life-blood of the laundering and textile rental industry for many years – but global production is falling.

Many of the textiles now processed by the modern laundry have increasing amounts of cheaper synthetic fibres such as polyester, polyamide and viscose mixed with cotton – making it increasingly difficult for the launderer to adequately care for them.

The Laundry Technology Centre (LTC) held a well-attended one-day seminar on textile purchasing and processing at The Wellcome Trust in London during November 2010.

The seminar was designed to give designed to give both laundry operators and their suppliers a better understanding of the processes involved in each other's business. It explored the changes that are taking place in textile manufacture, the effect on laundry processes and whether processing problems can be resolved or prevented from occurring altogether.

LTC’s Steve Anderton explained that the mixture of different fibres used in modern textiles is posing a wide range of additional technical problems for the launderer.

New manufacturing methods are having a profound effect on the performance, appearance and handling properties of the rental textiles supplied.

Anderton outlined the current crisis in cotton production.?He said that with the world population set to exceed 7billion people by 2012, environmental changes were having a catastrophic effect on agriculture in general. This in turn is affecting the food chain. Ever-increasing amounts of land are now required for food production, resulting in pressure to convert land for food production and away from commodities such as cotton.

World cotton production fell by 4.5million metric tonnes in 2008/9 as a result of changing weather patterns. It is projected that, to sustain current cotton demands and maintain current usage levels, cotton production needs to increase by 260,000 tonnes year-on-year. Anderton added that 110billion acres (an area twice the size of the UK) is needed to achieve current production levels – and this needs to increase by 1.1million acres (a little over half the size of Ireland) each year.

Anderton explained that all laundry processes and equipment had been developed mainly for handling cotton.

However, the increases in cotton prices and the need for improved processing efficiency within the laundry meant that many of the textiles now processed have increasing amounts of synthetic fibres, such as polyester, polyamide and viscose, mixed with the cotton.

Anderton said it was essential that textile manufacturers and distributors have an appreciation of the various laundry processes and procedures that have a direct impact on the performance of the fabric, just as it is also essential that the launderer has an appreciation of how textiles are manufactured.

Anderton set out to explain some of the common faults encountered by LTC in the past five years. His colleague Richard Neale completed the day by outlining some of the practical solutions.

Neale set out to explain clearly why the fault had happened and how the operator could prevent it from happening in the future.

Staining

Staining can be caused by a variety of factors an incorrect pre-wash temperature for example, or the wrong detergent or bleach setting.

Neale stressed it was important to classify the work correctly. Heavily soiled and stained work should be classified separately and processed accordingly, especially work that may require “pre-treatment”. He said that careful observation can identify whether the item was in use at the time the fault developed and how it occurred.

The colour, shape, size and position of any staining should be noted. If the staining or damage is over the whole item (and possibly affecting other items in the load), there is a strong probability that something went wrong during the wash process.

However, if the stain or damage is localised then it is more likely that the fault occurred before washing, soon after being removed from the washing machine or during use.

Holes, frays and tears

The pulling of threads can cause “bald” areas on woven towels or ladders on poor quality knitted towels. Holes and tears can also arise through accidents and through the progressive chemical degradation that takes place over several laundering cycles. It is important to understand these and to know how to prevent this kind of damage and where the customer can help.

Leading rental operators always keep back one or two samples from a new delivery so that if the level of holes in linen progressively increases then a check can be made on the suspect delivery.

Colour change

There are a significant number of users who prefer “colour co-ordinated” towels and sheeting. There can be some performance variation between different colours of towel depending upon the type of dye used and the method of application, as well as the depth of shade. For example, pastel shades are more readily affected by optical brightening agents and hypochlorite bleach than darker shades. As dye type and shade can vary, it is recommended that two or three of the most requested shades are assessed.

Shrinkage

There are several types of shrinkage and each requires a different type of treatment.

Almost all woven textiles will suffer some ”relaxation shrinkage” during the first few cleaning cycles.

Most textile cleaning processes involve total immersion, either in water or solvent.

This immersion relaxes the tensions left in the fibres during the spinning, weaving and finishing processes used in manufacture.

When the fabric is washed, the stretched yarns relax and the fabric shrinks. Gentle cleaning processes that reduce mechanical action and temperature may partially reduce shrinkage. It is readily accepted that some relaxation and wash shrinkage will inevitably take place during the initial five laundry cycles.

Most manufacturers and suppliers will cater for this in the “Cut, Make and Trim” (CMT) manufacturing process.

Neale said that once an item such as a sheet or pillowslip has shrunk, it is impossible to restore it to its original dimensions, irrespective of whether it is 100% cotton or a polyester-cotton blend.

Prevention is the best course of action. Take samples from each batch of textiles and carefully measure them before subjecting them to at least five normal wash processes, finishing the item in each case and then re-measuring after the tests and calculating the percentage loss.

Depending on the specification parameters given to the manufacturer, the item can be accepted or rejected on the basis of the wash test results.

Finish removal

The removal of the size that has been applied during textile production has become a big concern in recent years. Sizing of the warp yarn is essential to reduce breakage of the yarn on the weaving machine. Synthetic yarn-sizing agents include polyvinyl alcohol (PVA), polyvinyl acrylate and polyacetates.

The de-sizing process involves inserting the appropriate de-sizing agent into the fabric. As some fabrics are treated with water-soluble sizing, they can be de-sized with hot water.

Some mills include a mild alkali or wetting agent in hot water to help the process.

However LTC was concerned at the number of problems where normal laundering was unable to remove the sizing.

The company found that where garments had been treated with agents such as PVA for example, the size was not readily removed during a normal wash process. Although PVA is readily water soluble when originally applied – rather like the PVA paint applied to a wall – once it dries it become very brittle. With the mechanical action of the feeding equipment, the damaged PVA causes the fabric to have a mottled or “cracked ice”appearance.

Once the “cracked ice” creasing occurs on a new item it can take up to 10 – 20 wash cycles before it is effectively removed by the mechanical action of the wash process and the appearance becomes acceptable.

Neale said that it was essential that the correct specifications are given to the laundry supplier on specific fabric dressings.

In conclusion, Neale said that technical developments in textile finishing will allow the finisher to produce cotton and cotton blends that are completely satisfactory. However, the fabric buyer must specify both the quality and performance required.

Samples should be processed in the laundry to ensure that they meet specification and samples from each batch supplied should then be tested before the batch is added to the stock to ensure standards are still being met.

This testing will take time and involve costs but these are insignificant compared to that needed to deal with unsatisfactory goods.

Laundries should make sure that they specify the standards they expect textiles to meet, Neale concluded.