Bulletin - Helping you to meet footwear legislation

In recent years, chemical testing of consumer products has become increasingly important. With additional European, American and worldwide legislation, testing for the presence of restricted substances has become a significant part of the chemical testing available at SATRA. However, that is not all the organisation’s Chemical and Analytical Technology Group can offer.

Post-production discovery of toxic or hazardous substances can have significant financial implications. Therefore, if these are detected at an early stage, such implications can be minimised. SATRA recommends that restricted substances tests are carried out as soon as possible on prototypes and are then regularly done on production samples. Staff in SATRA’s Chemical and Analytical Technology Group are always on hand to advise and educate regarding restricted substances and legislative requirements, to ensure that this regulation and other customer specifications are understood. With the recent REACH legislation in Europe replacing the Marketing and Use Directive, bringing together all European Directives into one piece of legislation and introducing Substances of Very High Concern (SVHCs), restricted substances testing has become a key part of the service provided to SATRA members. Confirming the absence of these chemicals can result in reduced legal obligations and, in an age of increased consumer awareness, can give products an additional marketing advantage. As with all testing, the earlier that materials are assessed, the more time is available to evaluate any necessary alternatives.

SATRA’s chemistry laboratory

The chemical testing laboratory at the SATRA Technology Centre features analytical instrumentation capable of detecting substances to parts per million (ppm) levels. For the analysis of toxic heavy metals such as lead and cadmium, and the analysis of samples in accordance with EN 71-3 (which covers the migration of certain elements), use of the ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometer) is the ideal technique. The required elements can be quantified simultaneously, and this technique can also be used to identify the presence of other metals in materials. This can be useful when assessing discolouration problems or when screening materials for the presence of the SVHC chemicals listed in REACH Annex XIV.

For the analysis of restricted organic chemicals such as azo dyes, pentachlorophenol, organotin compounds or phthalate plasticisers, SATRA uses Gas Chromatography with Mass Selective Detection (GC-MS). These two instruments are situated in the laboratory and they are coupled with headspace (used to identify organic chemicals that can contribute to strong solvent odours), thermal desorption – for the analysis of sampling tubes used to monitor Volatile Organic Compounds (VOCs) – and standard liquid injection. The different techniques utilised ensure that a wide range of testing can be carried out using these instruments.

Other analytical instrumentation available includes HPLC (High Performance Liquid Chromatography) for the detection of formaldehyde, alkyl phenols and alkyl phenol ethoxylates, UV-Visible Spectrophotometry to determine the presence of chromium VI and allergenic latex proteins, and FTIR (Fourier Transfer Infra-red spectrometry) for the identification of polymeric materials such as polyurethane or polyvinyl chloride. This instrumentation can also be used to investigate adhesive bond failures through the detection of silicones, soaps or waxes, the presence of which are known to affect the degree of adhesion.

Discolouration

In addition to restricted substances testing and the analysis of materials, SATRA’s Chemical and Analytical Technology Group can investigate discolouration problems. These can arise through incompatible materials, where colour has migrated through the construction of footwear, and also due to additives in the materials themselves. White deposits on the surface of leather can be attributed to fat blooms and salt spues. Some formulations of synthetic polymers, such as polyvinyl chloride or polyurethane, can discolour if they are exposed to atmospheric pollutants, including oxides of nitrogen, hydrogen sulphide and UV light. This discolouration is usually seen as a uniform colour change and any areas protected from the atmosphere under non-permeable materials will be unaffected.

When heavily-dyed textiles are in contact with lighter-coloured materials, there can be colour transfer if the dye is not tightly bound to the material. SATRA has developed test methods to evaluate the potential for colour migration and to assess the propensity of a material to cause discolouration.

Innocuousness of products

As part of the European CE marking process for safety footwear and other safety products, the materials must be innocuous – that is, they must not contain any substances that might be harmful to the wearer. Testing for restricted substances is part of this innocuousness testing, and safety footwear claiming to be resistant to chemicals must also be subjected to additional chemical permeation testing. The materials must be resistant to at least three chemicals, from a list of fifteen listed in European Standard EN 13832-2 and for a minimum period of time in order to be certified as ‘chemically protective’ footwear. This permeation testing is also required for the assessment of chemically-resistant gloves and protective suits.

Main contacts within the chemistry team

Martin Heels is Head of the Chemical and Analytical Technology Group. He has worked in the chemistry laboratory for 12 years and has a first-class honours degree in Applied Chemistry.

Rebecca Shaw is the senior technologist and joined SATRA after graduation with a science-based honours degree. She represents SATRA on UK and European Notified Body toy testing committees – another area of expertise within the chemistry team.

With a degree in forensic science, Emma Collings undertakes some of the more complicated chemical testing required by our members. Emma has been with the chemistry team for four years and is involved with the development of SATRA chemical test methods.

David Merrell joined SATRA after 13 years’ experience in a textile testing laboratory and has a Batchelor’s degree in Applied Science. He is responsible for managing the day-to-day testing carried out by the chemistry technicians.

Michelle Peters joined SATRA in 2007 with a degree in forensic science. Michelle is normally the first point of contact for customers to advise the most appropriate testing procedures and assists with scheduling the laboratory testing.

Photograph shows SATRA’s Chemical and Analytical Technology Group team. From left: Martin Heels, Tom McNally, Max Bullock, David Merrell, Peter Mitchell, Emma Collings, Ben Wykes, Rebecca Shaw and Michelle Peters.