Laboratory testing for the leather maker18 June 2005
Introduction The only way to guarantee consistent quality and performance for leather and leather products is to ensure realistic specifications are coupled with a sensible and balanced testing regime. The testing regime must make certain that the key elements are measured without being financially onerous for the supplier. It is important to take into consideration physical performance whilst addressing legislative and brand protection issues such as tests for restricted or potentially sensitive substances. Testing can essentially be split into two areas, physical performance requirements and restricted substances. It is the restricted substance tests that are of particular interest currently. It is also useful to have an awareness of the background and situation related to development of test methods and the committees involved in this area. Restricted substance issues The BLC testing department has been through a number of changes since its conception. Looking back over the past five or six years, the profile of work received was very different from that seen today. Historically there was a larger proportion of physical trials carried out but over the years the amount of tests coming into the department has increased along with the types of testing received. The area that has seen the greatest expansion in the last few years is analytical and restricted substance testing. The main focus of BLC's advanced analytical team is to draw on its extensive knowledge of appropriate environmental requirements and analytical techniques, to be able to provide an accurate, reliable and fast response to clients. Questions which are often asked include the following: * Do you know what the environmental impact of leather making is? * Do you know what restricted substances could be present within leather? * Are there legislative requirements that you need to meet to enable you to sell your leather across the globe? * What testing should you carry out? * Which methods should be used? The answers to these questions are not simple and will vary depending on the leather produced and its final application. Generally it is possible to answer these questions only by keeping up to date with legislative requirements for restricted substances and more importantly by being able to provide an analytical technique to give an accurate reliable result. Various analytical techniques are available to the leather industry in order to assess the levels of various restricted or controlled substances. Also the techniques can be applied to assess levels of chemicals that are expected or indeed those that should be present in the leather. At BLC a range of analytical techniques are used including: * Gas chromatography with mass selective detection (GC-MS) including facilities for both static and dynamic headspace sampling * High Performance Liquid Chromatography (HPLC) systems with Diode Array Detection (DAD) * Atomic Absorption (AA) * UV/Visible Spectrophotometers * Fourier Transform Infra-red spectroscopy (FTIR) * Inductively coupled plasma optical emission spectroscopy (ICP-OES) These are used for the determination of many compounds including formaldehyde, petachlorophenol, various heavy metals and chromium (VI) to name but a few. Who's Who in Standards There are many methods of testing available to the leather industry. It is useful to be aware of the different bodies that develop these standards. * BSI - The UK standards institute. The committee TCI 69 is related to footwear and leather. Most countries worldwide have their own national standards body, eg DIN, ASTM etc * ISO - The international standards institute based in Geneva with member national standards institutes in 148 countries. The standards are internationally recognised, but are parallel to pre-existing national standards. The committee TC 120 deals with raw hides and skins (including pickled pelts), tanned leather and leather products. However, it does not produce test methods for leather * CEN - The European standardising body with member institutes in 26 European countries. The standards are recognised throughout Europe and member countries are required to withdraw conflicting national standards. The technical committee related to leather is TC 289. It has five working groups: * WG1 Chemical test methods (convened by Dr Amanda Long, BLC) * WG2 Physical test methods (convened by Dr Andrew Hudson, B & H Research) * WG3 Fastness test methods (convened by Dr Campbell Page, TFL) * WG4 Specifications and Terminology (convened by Sig Bargiggia, UNIC) * WG5 Raw materials (convened by Dr Jean-Claude Cannot, CTC) * SLTC - The Society of Leather Technologists and Chemists was historically the source of many leather industry test methods. Its technical sub-committee is responsible for the official methods of the society many of which have been adopted by the IULTCS. * IULTCS - The International Union of Leather Technologists and Chemists Societies is formed via membership of individual countries' leather societies. It has three commissions for chemical, physical and fastness tests (the chairs of which are currently held by the convenors of the corresponding CEN Work Groups). They are also the ISO technical committees for leather test methods. Methods developed can become ISO methods following a formal yes/no vote by ISO members. There is also an IUE Commission which aims to develop reference documents of good practice, with regard to the environment. Conclusions As can be seen, choosing the most appropriate mechanism for testing leather can be a minefield. To help negotiate this, the BLC recommended structure uses a simple model that includes tests for new suppliers (type), regular testing (batch) for existing suppliers and random (due diligence) assessments. * Type tests - when selecting a new supplier we recommend a full suite of physical and chemical tests on both leather and product. The scope for this varies depending on the product and its value * Batch tests - once a supplier has been selected, the specification provided and the first batch of leather type tested, the risk is reduced. Therefore, we recommend a reduced scope of tests that will cover the critical elements of product performance. These tests can be undertaken by BLC or conducted in-house in an approved laboratory * Due diligence tests - it is inappropriate to believe that processes will not change over time and a degree of risk management must be taken, especially for restricted substances, which may unknowingly be introduced into the leather or production process by the supplier. Therefore, an element of calculated random testing is introduced into the protocol which is determined by the type, value and numbers of product BLC remains committed to analysing legislation and working to develop new test methods which are appropriate to leather suppliers and their customers.