Contamination and Cross-Contamination in Paint Manufacture

The Challenges for the Paints and Coatings Industry

pigging and paint manufactureContamination and cross-contamination in paint and coatings manufacture is a serious issue. And, it can occur at any point along the chain – during production, processing, distribution, or preparation.

Contamination generally refers to products that are spoiled or tainted. This is either because they contain microorganisms such as bacteria or parasites, or other substances that pose a threat to human health and the environment.

Meanwhile, cross-contamination refers to the passing of bacteria, microorganisms or other substances indirectly from one substance or object to another or even one type or colour of paint with another. It can take many forms – dust, fibres, spillages, insects and more. It can also be caused by machinery and other production equipment. For instance, during product changeovers when changing from one colour paint to another.

This article looks at some of the causes of contamination in paint manufacture (in particular bacterial contamination), the implications of environmental regulations, and why an increasing number of paint manufacturers are using product recovery (pigging) systems to help.

Contamination Can Impact an Entire Supply Chain

As well as posing a potential health threat, contamination and cross-contamination are a substantial risk to product quality. At the same time, they can have detrimental effects to a company’s reputation and customer confidence in the paint manufacturer.

A contaminated batch of paint also has major economic implications for paint firms. For instance, there’s the direct costs of raw materials, as well as the logistics of recovering and destroying the contaminated products.

Water-based Paints and Bacterial Contamination

The types of microbial attack that are of major concern to paint and coatings manufacturers are bacterial, fungal and algal. While only paint formulations containing high levels of water are susceptible to bacterial contamination in the can, both water and solvent borne coatings are susceptible to an attack on the applied and cured paint film by fungi and algae.

The primary reason waterborne coatings are vulnerable to bacterial contamination is because of their aqueous nature and organic origin. This provides a more hospitable environment for certain types of bacteria to survive and thrive. The presence of bacteria can have an influence on the final paint properties. It can cause changes in physical and chemical properties, resulting in a spoilt product. Signs of a spoilt product may include a change in smell, discolouration and viscosity changes. All which can have a significant impact on shelf life. And from a consumer’s point of view, who wants to use a paint that’s smelly, or not the right colour or texture?

To prevent the proliferation of bacteria and other micro-organisms, biocides (or paint preservatives) are typically added to the paint formulation. Biocides kill the microbes, and protect the paint from spoiling. What’s more, they increase the shelf-life of the formulated products, and allow for a considerably longer storage capability.

Paint bacterial contamination

Biocides Environmental Regulations

Unfortunately for the paint industry, environmental regulations have become increasingly stringent and have severely restricted the use of certain biocides considerably. This is due to their adverse effects on human health and the environment. This has proved difficult for paint manufacturers. Many consider this a ban, due to the stringent concentration limits which means the preservatives will no longer be effective at that level. Therefore, paint manufacturers face finding an alternative method of preservation that will protect against contamination both during production and in-can.

With certain biocides banned completely and more restrictions on the horizon, the industry’s options to preserve its paint are rapidly shrinking. If further restrictions materialise, this could limit the ability of paint manufacturers to vary their preservatives. Therefore, this could stimulate tolerance to them among biological contaminants.

Environmentally-Friendly Sustainable Paints

Due to regulations and increasing green awareness among consumers, there’s been a transition towards sustainable, waterborne paints. While these low- and zero-VOC paints (a VOC is a Volatile Organic Compound) are less toxic than traditional biocidal paints (as they release fewer VOCs in the air), they often have a higher water content.

As a downside, these formulations are considerably more susceptible to bacterial degradation and spoilage. Therefore, paint formulators are increasingly using biocides as in-can preservatives to protect them against spoilage.

Changes in legislation have fuelled significant changes in the biocides market. This has forced paint manufacturers to look not just to alternative preservatives, but also towards hygienic production. An increasing emphasis has been placed on good manufacturing practices, plant hygiene and robust processes and procedures. As a result, many companies are adopting new manufacturing technology and processes such as hygienic pigging.

Why Paint Manufacturers are Using Hygienic Pigging Technology

Inhibiting the growth of harmful bacteria and minimising the risk of cross-contamination is essential in hygienic environments like paint and coatings manufacture. Because microbes are unable to thrive without sufficient moisture, a hygienic and dry environment can support deterrent efforts. And that’s where pigging comes in.

A build-up of paint residue on the internal wall of the pipe provides optimal conditions for bacterial growth, therefore this needs to be removed. Many well-known paint and coatings brands use HPS pigging solutions to recover and remove paint residue in the pipelines, and to improve the efficiency of their operations.paint and coatings environmental regulations

That’s because our highly efficient process pigs typically recover 99.5% of the residue in a single run. At the same time, they’re extremely flexible and will easily travel around 1.5 D bends while maintaining constant, full body contact. Because the pig has an interference fit, it forms a robust seal with the inside of the pipelines, which ensures no product bypass. So, as the pig is pushed through the pipelines, it forces the residual product along with it leaving very little, if any residue. So not only does pigging help reduce the risks of bacterial contamination in paint manufacture, it also reduces risks of cross-contamination during product changeovers, including colour contamination from one product to another.

Extensive Range of Benefits for Paint Firms

As well as being highly effective in obtaining the required level of cleanliness of the transfer line, pigging technology has many other benefits. This includes the reduction of flush waste, higher yields, water reduction and the speed up of changeovers.

A paint manufacture may also use the same pipeline for different colours, and the type of paint it processes. During product changeover, there may be paint residue in the line from the previous batch. This is because some of the paint will cling to wall, and leave smears in areas of the pipelines. To prevent contamination of the next product, it’s vital that all of this product is removed with a pigging process prior to changeover. Therefore, this eliminates cross- contamination risks and the economic losses associated with this.

Find Out More

There’s more information about paint and coating companies that have implemented product recovery systems in our pigging systems case studies.

For further information about minimising the risk of contamination and cross-contamination through pigging and product recovery solutions, please contact HPS.