Airborne rust - a superficial problem?

Wrede Technologies explores the threat of airborne rust and considers what superyachts can do to mitigate potential damage...

To avoid long-term damage to superyachts caused by airborne rust, timely and accurate identification of contamination is required. A superficial diagnosis may result in inappropriate cleaning or repair, in turn resulting in higher costs. Technologies such as 3D microscopy provide new options for detecting contamination from rust particles and selecting the right treatment.

Airborne rust is iron dust that rusts in the air. The particles usually originate from nearby metal objects and settle on other surfaces. This is a threat that also exists in ports and shipyards. For example, one source of contamination for a nearby yacht may be a ship being subject to water jet or high-pressure cleaning. If the particles are not properly removed early on, they will penetrate into the surface and cause greater damage. For this reason, it is first necessary to determine whether there are individual rust particles on the paint film or have already baked into it.

There are many different methods for removing rust particles. Surface cleaning using various chemical substances is often carried out. Other options are high-pressure cleaning or rinsing with deionised water. To recondition the surface, it can be polished, sealed or lacquered, depending on the damage. “But use caution: choosing the right treatment for such contamination requires careful analysis. Treating the surface incorrectly can have expensive consequences,” says Jan Reygers, Project Manager at Wrede Technology GmbH (WRETEC). The Hamburg-based company specializes in the scientifically sound analysis of yacht coatings. One of the ultra-modern instruments in WRETEC's laboratory is a digital 3D microscope that enables individual coating layers to be enlarged up to 5,000 times and displayed as 3D images on the monitor.

No guarantee: conventional identification of rust contamination

The conventional method for identifying and treating contamination with rust particles involves macroscopic, visual inspection of the damage. Damage is recorded and documented with the naked eye or with the aid of a magnifying glass or camera. A variety of methods and substances are then used to wash the affected areas until the visual impression is once again satisfactory. A gloss level measurement can also be used to provide a before and after comparison. The problem is that only superficial elimination of the damage can be carried out on the basis of the surface analysis. There is no way of assessing possible consequential damage. Even the choice of the right repair or cleaning strategy is therefore only partially reliable. As a result, the work involved may not be sufficient, for example by simply cleaning without sustainably removing the damage. Or it results in high costs from excessive effort such as unnecessary repainting. Moreover, documentation of the damage is rather superficial. A distinction between “discoloured” before treatment and “cleaned” after treatment is made here. The lack of quantification and qualification of the actual pattern of damage makes prognosis of future damage much more difficult. 

Analysis of the future: Identification using a 3D microscope?

WRETEC has made it its mission to make the analysis of coating damage of all kinds as precisely as possible with the aid of technologically sophisticated methods and to thus create the basis taking the appropriate action. “With our instruments, we are able to very precisely determine the causes of anomalies in the coating,” says Jan Reygers. “Similar to the field of medicine, symptoms that at first appear to be the same can have very different causes.” For a sustainable solution to the problem, damage should therefore not be repaired using a one-fits-all approach. It is better to identify the root cause of the problem beyond any doubt and to find a tailor-made solution. Digital 3D light microscopy is generally able to identify even the smallest particles in individual layers of paintwork.

With respect to airborne rust, WRETEC has developed an analysis method that goes beyond assessment with the naked eye. From microscopic, three-dimensional examination of representative areas of damage, precise documentation of the pattern of damage can be made for possible claims for compensation. There is also an accurate reference for before and after comparisons. Both quantifying statements about rust particle size and qualifying statements about particle type are made. With this non-destructive method (NDT), in addition to type and size, the degree of particle corrosion is measured before treatment. WRETEC's experts also analyse the depth of rust particle penetration into the paint. This makes it possible to assess the extent of damage far beyond visual observation: If the paint surface is mechanically destroyed, oxidation products can penetrate below the paint surface into the coating and cause consequential damage even after superficial removal. 

It is also possible to identify whether "baked-in damage" from hot particles is present in the chemical paint structure or oxidation products are already present in the particle environment. This gives surveyors, such as Wrede Consulting's paint consultants, a broad basis of facts and enables them to recommend a suitable cleaning or repair strategy with a high degree of certainty. 

Relevant prognoses for owners, insurance companies and the parties responsible for the damage
After the damage has been treated, reliable assessment and documentation of any residual contamination and permanent micro damage is carried out. However, if these remain undetected and untreated, they reduce the protective function of the paint surface and allow moisture to penetrate deeper into the coating structures with discolouration and blistering as possible consequences.

Based on this detailed information from the microscopic 3D examination, a surveyor is also able to make a long-term prognosis about the service life of the affected areas of paint. Without this knowledge, large micro lesions that cannot be identified with the naked eye can drastically reduce the interval until repainting becomes necessary and thus increase maintenance costs. Such a prognosis is therefore of great interest for both the parties causing the damage and their insurance companies as well as for the affected owners.

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Wrede Consulting GmbH

WRETEC-Wrede Technologies GmbH

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