Investigation into Chrome 6 in paint in full swing

How do you measure whether chromium 6 is in paint? And how can you remove paint containing Chrome 6 without risk? Bjond Innovation is working with the Department of Public Works and various market parties to investigate this. The goal is to come up with careful solutions as soon as possible.

Paint containing Chromium 6 is often applied to objects made of steel and concrete in wet outdoor environments, such as on railroad bridges, lock gates, water barriers and viaducts. Usually in bright colors. This is because Chromium 6 provides excellent color stability while being a good oxygen scavenger that enhances the corrosion protection of the coating. By itself, Chrome 6 in paint does not pose a problem. But it does become one as soon as you remove the paint and dust is released, such as from sanding or blasting. Like asbestos, this can cause health problems. Because of the affair at Defense where people were exposed to excessive amounts, the law has been tightened. The legal exposure limit to Chromium 6 in paint is now minimal: 1 microgram/m³ or 0.001 milligram/m³ (as TGG-8 hours).

Multiple coats of paint containing Chrome 6 on concrete.

Research Trail

Bjond Innovation, a consulting and research firm from Maaseik (Belgium), has been asked by Rijkswaterstaat to coordinate the research project "Measuring chromium 6 in paint. Bjond deals with issues concerning the protection of concrete and steel in the broadest sense of the word. Its work, which includes advising, inspecting, innovating and providing knowledge-intensive services, mainly concerns complex problems related to corrosion protection. The agency works 80 to 90 percent for government and industry in the Netherlands and Belgium. Director Jo van Montfort calls chromium 6 in paint currently a hot item in the conservation world. "Together with various market parties, we are evaluating analysis methods to find out how you can reliably determine whether chromium 6 is present in paint. To this end, we have taken samples from preservation systems on steel and concrete. These were analyzed by various laboratories to see what the best method is for this. With the ultimate goal of reaching a national agreement on how to measure this and how to determine it reliably and reproducibly. It is important to realize such an agreement quickly but above all carefully. At the same time, we are investigating how to remove this paint as smartly as possible. What means can you use for this?"

Bridge asking for maintenance.

Testing methodologies

Several studies on laboratory analytical methods have since been conducted, the results of which are now being evaluated. Likewise, reference samples with known amounts of Chromium 6 are being made that will be studied again in a ring trial to see which method of measurement is the best. "Paint is a complex material with many components that can interfere with its analysis. Especially with multiple layers. We are now trying to get a grip on that in order to improve the reliability of the analyses," Van Montfort said.

Fly rust on steel substrate after wet-blasting.

Paint Removal

There are methods for removing paint containing Chrome 6 that have not yet been well evaluated, such as wet blasting techniques. These are little used because of the rusting they induce. Everything is usually blasted dry. But wet blasting releases less dust. Then, of course, the water droplets must not contain chromium 6. To counteract this, all kinds of cleverness are now being devised. Van Montfort: "We ourselves are developing a primer that can be applied to slightly rusted and wet steel. The tests look very promising!"