Ethical cotton brings problems and opportunities2 September 2019
Ethical sourcing of cotton is very much the order of the day. Richard Neale of LTC Worldwide looks at how to maintain the product’s ethical integrity during the laundering process
Ethical cotton is produced under controls just as rigorous as those for growing organic food. It is natural fibre, unadulterated by strong chemistry, by chlorine bleaching or by optical brighteners. It is traded fairly at every stage of the manufacturing chain, following the principles of minimum impact on the environment as far as carbon emission or chemical contamination is concerned.
Leading hotel groups are now taking ethical standards into their purchasing decisions, not just for the ‘green and ethical’ image associated with this, but also because of the qualities of the ethical product itself. Hotel linen made from ethical cotton is pure 100% natural cotton fibre, with a delightful soft handle, excellent drape, superb ‘breathability’ for the sleeper in the bed and none of the symptoms of chemical modification or degradation that could be associated with its traditionally produced rivals.
This presents a challenge for the contract launderer, because in order to preserve its ethical claim, it should be washed to the same standard as it is produced. This month we look at the implications for the laundry process and the consequences of these.
Principles behind ethical cotton
The principle of having minimum harmful impact on the environment must apply to every step from seedling to final disposal, so the plants are grown following organic criteria and ‘fair trade’ thinking is applied to farming production, including watering, fertilisation of the soil and harvesting. In spinning and weaving, modern minimum energy processing ensures minimum carbon emission. Oxidation damage to the cotton fibres is avoided by aiming for a natural coloured cloth, hence the banning of chlorine bleach. Warp sizing to speed the weft traverse in weaving (by lowering the coefficient of friction between warp and weft) fits well with this, because it further minimises weaving energy and enables higher loom productivity. Warp sizing needs to be chosen carefully, as not all of these substances used in the warp sizing are naturally occurring and can be easily removed without the use of aggressive chemistry in cloth finishing, so that the finished textile is free of any chemical residues and the wash liquors discharged to drain are environmentally acceptable.
Maintaining the colour without chlorine bleach
Ethical cotton has a creamy white colour and maintaining this natural shade calls for a complete ban on chlorine bleaching using sodium hypochlorite. This chemical is widely used in both contract and rental laundering to create an ‘ice-white’ shade, but it attacks any dye (including the natural creamy shade of ethical cotton) and it damages the cotton fibre itself. The damage is not great, provided it is used at the correct temperature and concentration, but in a modern tunnel washer it can be difficult to keep within safe limits and unintended damage to the cotton itself frequently occurs especially in rewash or recovery processes. This shortens textile life and has a significant effect on the viability of any cotton textile purchase. Equally importantly, discharge of chlorine bleach residues into rivers and oceans has a serious detrimental effect on plant and fish life. This has been corrected in Europe, which has several very long, high-volume, slow flowing rivers, by progressive tightening of discharge consents, so that chlorine bleaching in continental laundering has largely become a thing of the past. It continues in other parts of the world, but it is not permissible if the hotel group wishes to maintain its claim, to offer to the guest bed-linen and towelling made from ethical cotton.
Eliminating optical brighteners
Banning the use of chlorine bleach alone is not sufficient to maintain the colour of ethically produced cotton. It is also necessary to outlaw the use of optical brighteners, which are special additives widely applied to cotton sheeting in textile finishing. An optical brightener attaches itself to the cotton fibre with the tenacity of a high-quality dye. It forms an invisible layer over the cotton yarns, from where it reacts with the ultraviolet portion of natural light. The wavelength of pure ultraviolet makes it invisible to the human eye, but an optical brightener will turn this into brilliant white light in the visible spectrum. This can create twice the amount of visible white light from the textile, diluting the natural creamy shade of the ethical cotton to produce a rather unsightly greyish white. This is definitely not what the customer has been led to expect and would lead to certain complaint.
Banning optical brighteners from the textile finishing process, after weaving, is only half the battle (and much the easier half). A great many commercial laundry detergents contain optical brighteners, which are designed to build-up progressively on the textile surface with every successive wash. Avoiding totally the use of these in a busy laundry can be a challenge, because even a single, accidental wash using a detergent containing a brightener will cause colour damage which is not easily reversible. Once the brightener in the detergent has bonded onto the cotton in the wash, it cannot be removed without the use of quite harsh chemistry (which would defeat the ethical claims which this is all about). The best solution to this problem is to set up a dedicated processing line in the laundry for washing, drying and ironing ethical cotton. This is somewhat impractical in many laundries, but it has been achieved. This processing line can be rendered completely free from any risk of contact with either chlorine bleach or optical brighteners. This obviously calls for a sufficient daily volume of ethical cotton to justify it.
Overcoming laundering problems
The obvious and major problem for the modern launderer is how to overcome the effect of a wash process which does not have any chlorine bleach in it. This problem is magnified in those laundries in which chlorine bleach has been misused to make up for an inherently poor process design. This generally occurs when the basic detergency of the process is inadequate to remove fatty or oily protein soiling and staining from the cotton fabric. It has been far too easy in the past to simply raise the dosage rate of chlorine bleach to ‘burn’ fatty protein staining off the cloth chemically, instead of correcting the wash process. Softening protein stains with pre-wash held below 40C for at least four minutes, is the essential first step, after which they should come away with good mechanical action and detergency in the main wash. Bleaching of protein stains should be completely unnecessary.
This leaves vegetable dye stains from tea, coffee, red wine, blackcurrant, beetroot and so on. The majority of these come away with prompt laundering, but where this is not possible then mild oxidation is needed, using a weak solution of hydrogen peroxide in the main wash for example. This breaks down into oxygen and water and leaves no undesirable chemical residues on the fabric. Hydrogen peroxide has little or no effect on protein stains, which is why it has an undeserved reputation as a ‘weak’ reagent. This has been propagated by launderers who cannot remove protein stains correctly; hydrogen peroxide is superb at removing the vegetable dye stains just listed. Also, it works best in the main wash, with none of the dangers of excessive textile damage associated with getting chlorine bleach into this stage.
The cost of bleaching of vegetable dye stains with hydrogen peroxide is several times that of using chlorine bleach, but this cost is so small anyway, that the effect on the overall processing cost is acceptable. Some laundries only bleach on the rewash or recovery processes, which further minimises both costs and chemical action.
The detergent for ethical cotton must obviously be free from chlorine bleaches but other ingredients have significant environmental impact also. These include phosphate, which has largely been eliminated and non-ionic surfactant which is commonly used as an emulsifier. The products used must not leave any chemical residues on the cloth surfaces. There are now many detergents available which satisfy these criteria, enabling launderers to justify claims of maintaining the same ethical standards under which the cotton fabric was manufactured.
Following these principles will minimise damage to the cellulose molecules in the cotton fibre, which in turn will maximise fabric life. This will manifest itself as a typical increase in textile life of perhaps 10 -20 wash and use cycles. However, if this is accompanied by expert and careful handling in use, transit to and from the hotel and in laundering, then the commercial life could easily be increased from say 150 wash and use cycles to over 200 cycles. This is being striven for by users of ethical cotton, not just for the considerable financial implications, but because it fits with the ethical principle of maximising the recycle potential of the circulating stock of hotel textiles.
Hotel linen needs normal commercial disinfection in order to control the potential spread of harmful bacteria. This can be achieved either by laundering in accordance with the criteria for healthcare disinfection (a main wash which runs for at least ten minutes above 65C) or by using approved natural disinfectants, which cause no damage to the linen and leave no chemical residues on the fabric. Some micro-organisms resist disinfection by either of these routes – for example, bacillus cereus and clostridium difficile. For these, dilution in the rinse remains the most effective solution. This calls for efficient rinsing with no overloading. Using inter-spins in a washer extractor or split rinsing in a tunnel washer will both help with this. However, many detergent suppliers now have low temperature processes offering disinfection, thus, reducing the carbon footprint of the laundry and adding to the environmental credentials.
The challenges involved in the successful processing of ethical cotton are not for the faint-hearted, but by following the principles in this article, any competent launderer can maintain the delightful product features which are making this product increasingly popular with forward thinking hotels. The results achievable with ethical cotton should include significantly improved product life, with a soft handle and natural colour right up to the end of this.