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Testing clothing detergent claims

The UK laundry detergent market is worth over one billion pounds each year and in such a competitive market it is important for manufacturers to make their products more appealing by claiming to offer outstanding performance. Claims include increased brightness, colour fastness, eco-friendliness, or the ability to remove stubborn stains at low temperatures. SATRA provides an overview of testing clothing detergents

The types of laundry detergents may vary, from liquids to powders and tablets to capsules, biological and non-biological, for whites and for coloured fabrics, but each format needs to be able to prove its product claims in the same way.

HOW IS PRODUCT PERFORMANCE TESTED?
The effectiveness of laundering depends on several factors: the detergent, the water temperature and hardness, the washing machine, the soiling severity and the textile which is being washed. Wash and water conditions (hard or soft) are agreed with the client prior to testing, as is the mass of the wash load and the types of materials placed into the wash as ballast.

STANDARD STAIN TESTING
Laundry product manufacturers often ask for their product to be tested against a range of common stains, including food, grass, wine and ink. For most purposes SATRA’s laundry care team carries out tests using a range of commercially available pre-soiled staining cloths, as follows:

  • carbon black and mineral oil (particulate soil removal)
  • cocoa (hydrophilic staining)
  • red wine (bleaching ability)
  • China ink also called Indian ink/milk/blood (protein staining)
  • coffee
  • curry
  • grass.

Additionally, clients can specify other stains that they would like to test against, such as tea, Bolognese sauce, or blackcurrant juice.

The pre-soiled cloths are usually washed using multiple similar domestic washing machines, each machine being used to carry out an evaluation using each of the wash products under test. This gives a good average set of results.

The colour of the pre-soiled cloth can be checked prior to washing using a Chroma Meter. After washing the test fabrics are then re-measured. The results obtained from the measurements before and after washing are then used to demonstrate objectively how effectively the stains have been removed.

SATRA has a test protocol for use in assessing the performance of laundry products and this may be modified to include alternative sets of stains and cleaning procedures in order to assess specific cleaning properties within a detergent.

ENVIRONMENTAL CLAIMS
Along with the effectiveness of a product, many of today’s consumers are looking for products that make less impact on the environment. The European (EU) Eco-label is a voluntary scheme designed to encourage companies to make and market products and services that are kinder to the environment, and that can be easily identified as such by means of the EU Eco-label flower symbol.

Products qualifying to carry the EU Eco-label have been shown to meet the following criteria:

Reduced amount of chemicals: To carry the EU Eco-label, products must not contain total levels of chemicals in excess of maximum limits specified for the various types of products included in the laundry detergents product group.

Limitation of substances harmful to the aquatic environment: Critical dilution volume limits which must not be exceeded are specified for the various product types. These are expressed as the volume in litres of water per kilogram of product required to ensure that the product is not harmful to the aquatic environment.

Increased biodegradability: To meet this requirement, the content of organic substances in the products that are non-biodegradable must not exceed specified limits.

Reduced packaging: For laundry detergent product packaging requirements, weight/utility ratio (WUR) limits have been set. For powders, the limit is set as 1.2g/kg wash and for other products as 1.5g/kg wash. The WUR is calculated only for primary packaging (including caps, stoppers and hand pumps/spraying devices).

Plastic/paper/cardboard packaging containing more than 80 per cent of recycled material is exempted from the requirement.

Safety of the product: A number of specified ingredients must not be included in the product, either as part of the formulation or as part of any preparation included in the formulation. Certain EU risk phrases and hazard statements indicate constituent substances (or release substances) which no product may include. Such statements include: ‘may cause cancer’ or ‘may damage fertility or the unborn child’.

Instructions for best environmental use: Dosage recommendations shall follow the requirements in the Detergents Regulation 648/2004/EEC and must appear clear and readable on the product packaging. Information on the packaging is to highlight appropriate washing advice and must include instructions to ‘Wash at the lowest possible temperature’ and ‘Always wash with full load’. The label should also say that ‘Using this Eco-labelled product according to the dosage instructions will contribute to the reduction of water pollution, waste production and energy consumption’.

satra_stain_sheetsTested and guaranteed wash performance: An EU Eco-labelled product will have been compared in its washing performance with a reference detergent, according to the EU eco-detergents performance test ‘Award of the EU Eco-label to laundry detergents: performance test of household detergents’.

Wash performance testing: A wash performance test ensures that a detergent will clean textiles in an efficient manner when used at the correct dosages as recommended by the manufacturer. Testing against EU Eco-label requirements, however, also assesses other important characteristics of washing performance, such as fibre damage and build-up of encrustations on fabrics, which can decrease the flexibility of fibres and possibly shorten the fabric life. This is done by carrying out multiple wash cycles but without any intermediate wear periods.

The basic principle of a wash performance test is to compare the test detergent with a standard reference detergent of known satisfactory performance properties. The test is carried out using 25 cycles for heavy duty and ‘colour-safe’ detergents and 15 cycles for light duty detergents. Special white clean, soiled and stained swatches are used as controls or monitors for determining cleaning performance.

Whiteness and colour change are calculated from colour measurements taken on standard white cotton cloths, which are also used in the tests for monitoring of fabric damage and fabric encrustation.

Soil and stain removal are determined by measuring the intensity of the colour of the monitors before and after washing and calculating difference values which are compared to those for the reference detergent.

Dye transfer for ‘colour safe’ detergents is determined using a standard cotton or polyamide nylon fabric as a dye acceptor, and a dyed fabric with poor water fastness as a dye donator. Samples of the two fabrics are washed together at the appropriate temperature in a washwheel type apparatus containing a wash liquor prepared from the test detergent. A control test with no dye donator fabric is also carried out. Colour differences between the standard fabrics from the two tests are determined using a spectrophotometer.

Criteria, summarised in the following table, are specified for the minimum standards of washing performance which have to be fulfilled by the different detergent products under test in order to meet the requirements for the EU Eco-label. A product meets the requirements if it shows better or equal results in all criteria than a calculated value which has been derived from the results obtained for the reference product.

The testing procedure is scheduled to be simplified while still ensuring that products meet stringent criteria.

About Sarah OBeirne

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