14. Jul 2017 |
Zero VOC Paints – are they really better for the environment?
In an ever more competitive marketplace, paint companies are looking for new and different ways to stand out, including promoting the green credentials of their products. One criteria that has been used (or perhaps more accurately mis-used) as a differentiator in recent years is Volatile Organic Compound (VOC) content. VOC is a general term referring to any organic substance with an initial boiling point less than or equal to 250 degrees Centigrade (European Union definition) that can be released from the paint into the air, and thus may cause atmospheric pollution. VOCs are volatile organic compounds that can be naturally occurring (such as ethanol) or can be synthesised chemically. The VOC content in water-based paints may be a very small amount of solvent or trace levels of additive in the paint that are needed to enhance its performance – for example, to help the paint flow out and give an even surface. It is important for the consumer to be aware of the true impact of painting on the environment, what VOC content actually means, and especially the questionable use of terms such as ‘Zero VOC’ and ‘VOC-free’ by certain decorative paint suppliers in the UK.
VOC Content – following the law
In terms of VOC content, the decorative paint industry across Europe is required to follow their own national legislation, based on the European Paints Directive 2004/42/EC. This directive controls the VOC content in decorative paints (and paints for vehicle refinishing), thus reducing their environmental impact. This had a major impact on the paint industry, accelerating the move to water-based paints and the development of new materials that would permit lower VOCs to be used in paint without compromising its performance. The Directive revolves around a series of limits (maximum VOC content) for each category of paint, according to its type and application. For example, a typical interior matt paint for walls or ceilings has a maximum VOC content / limit of 30g per litre. Paint manufacturers demonstrate their compliance by showing the VOC content of their paint on the product label, referring to the appropriate category and limit. Many matt wall paints on the UK market now have less than 10g / litre or even lower levels – these are measured according to agreed international standards using appropriate analytical methods. So, these types of paints have a very minimal impact on air pollution and the environment. However, it is important to note that there is no mention whatsoever of the term ‘Zero VOC’ or ‘VOC-free’ in the Directive, in any related legislation, or in the standards used to determine the VOC content of paints.
Zero VOC claims – what’s wrong with them?
Paint is made up of a number of components. Some of these may be of natural origin (such as minerals, chalk, clays or natural oils), other components (such as binders, pigments and additives) are more often synthetically-derived from different industrial chemical processes. All these components need to undergo some degree of washing, refinement, processing or chemical treatment, so they can be successfully used to make paint. These production steps necessitate the use of different process aids, including substances that are classed as VOCs. Although every effort is made to remove these VOCs through drying and purifying, there will still be trace amounts in the finished raw materials that are used to make the paint and the tinting pastes that are needed to be used. Therefore, there is no such thing as a truly 100% VOC-free or Zero VOC paint, as all paints will contain very small (trace) amounts of VOCs through their raw materials. Given that no paint is truly VOC-free, the paint industry across Europe (as represented through their trade association CEPE) agreed in March 2013 not to use Zero VOC claims in the promotion of their products. Similarly, all the major UK manufacturers of decorative paints, who are members of the British Coatings Federation (BCF), confirmed the same position in November 2015. The BCF statement also emphasised the point that companies using Zero VOC claims are not following the UK Government’s guidance on green claims, which refers to the need for companies to make ‘clear, accurate, relevant and substantiated claims’ to avoid misleading consumers. Unfortunately, there are several paint suppliers in the UK that are persisting with the use of Zero VOC / VOC-free claims for their products, despite the industry’s best efforts to bring the issue to their attention. Several media articles have referred to paint below a certain VOC content (e.g. paints containing less than 0.2% VOC), being regarded as VOC-free, however this is incorrect and is certainly not a recognised approach within the UK paint industry or in Europe. The mis-use of Zero VOC terminology in the US is also having an impact on the UK coatings sector, as they commonly label any paints with less than 5g / litre as ‘Zero VOC’ products, and some companies are importing such paints into the UK market. The use of these claims for paints is therefore both incorrect and unjustifiable – there is no definition for ‘VOC-free’, nor recognised analytical test that can be used to demonstrate a paint as having zero VOC content. Therefore, members of the public continue to be mis-led when purchasing their ‘Zero VOC’ paint, which is not free of VOCs and consequently is not proven to be any better for the environment than other decorative paints on the market.
Environmental foot-printing and paints
So where do we go from here? How can consumers choose a paint that will have a minimal impact on the environment? What criteria can be used instead of VOC to select an environmentally-friendly product? The paint industry, along with 26 other piloted sectors, is currently working with the European Commission on a project to determine the overall environmental impact of consumer products, from the start of their production to the end of their lifetime (so-called cradle-to-grave approach). This project, called the Product Environmental Footprinting or PEF project, is due to be completed within the next two years, and should lead to a better way to inform consumers, probably through a new simple labelling system and possibly supported by legislation. This should represent the culmination of the last two decades of focus on sustainability and measuring environmental impacts, not just in terms of VOCs causing air pollution but also in terms of water usage, ozone depletion, toxicity to soil and water, and a host of other parameters. This is still a few years away, but it is clearly a much more comprehensive and holistic approach to judging the environmental impact of consumer products, rather than using selected single criteria such as VOC. There are several key contributors to the environmental footprint of household paint – the extraction / production of the raw materials, the cost of transporting paint from factory to retail outlet to your home, and how long the painted surface will last until it needs repainting i.e. how durable the paint film is. This last aspect is of particular interest – a durable longer-lasting paint is better for the environment. Many paints which claim ‘Zero VOC / VOC-free’ credentials are based on natural clays and oils rather than synthetic binders such as vinyl or acrylic. This has an impact on how resistant the paint film is to water or to damage – generally synthetic-binder based paints will provide a much more durable and resistant paint film, so would be expected to last longer than a clay paint. Thus, walls with these clay paints on may need repainting more often, and the clay paints would not score so well, when viewed from an overall environmental footprinting approach. Thus, perversely, ‘Zero VOC’ clay paints may actually be more harmful to the environment than standard synthetic-binder based paints, due to this increased maintenance cycle. In conclusion, the message to consumers is to take a minute to consider whether they’ve chosen the right paint for the job, and that whatever claims associated with the product, especially regarding the impact on the environment, are accurate and can be justified.
The Rheology Handbook
Already in its 5th edition, this standard work describes the principles of rheology clearly, vividly and in practical terms. The book includes the rheology of additives in waterborne dispersions and surfactant systems. Not only it is a great reference book, it can also serve as a textbook for studying the theory behind the methods. The practical use of rheology is presented in the areas quality control, production and application, chemical and mechanical engineering, materials science and industrial research and development. After reading this book, the reader should be able to perform tests with rotational and oscillatory rheometers and interpret the results correctly.
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