Layer by layer, less harmful substances

Innovative clear varnish system is promoting green MRO

Like all the other materials used in aircraft construction, the high-gloss polished wooden surfaces that are typically installed in VIP cabins have to meet the highest safety standards. For optical purposes and to comply with fire protection regulations, these surfaces have to be treated with effective flame retardants and clear varnishes containing a high proportion of organic solvents. To relieve the environment and better protect the health of its employees, Lufthansa Technik has conducted research into alternative systems.

To achieve the desired quality, up to ten coats of clear varnish are applied to the wooden decorative surfaces. To ensure the required degree of gloss and high durability, a final, special top coat is then applied. Apart from the usual additives (auxiliary materials that are added to the coating substance), industry-standard clear varnishes consist almost entirely of bonding agents and solvents. Whereas bonding agents serve as the raw material for the later constituents of the varnish, the solvents determine the flow and curing characteristics of the varnish. Once applied, the solvent evaporates entirely during the drying process.

However, during the evaporation process volatile organic solvents can not only cause unpleasant odors but they can also harm human health and the environment. As it is not possible to dispense entirely with solvents in varnishes, the challenge is to reduce the proportion of solvent to a minimum. At the same time the varnish must demonstrate the resistance to fire required in aircraft, it needs to be neutral vis-à-vis environment and health while nevertheless exhibiting the shine desired by the customer. And ideally the materials and manufacturing processes involved should not entail any extra cost.

To satisfy these diverse and extremely demanding requirements, Lufthansa Technik initiated the "Environmentally friendly varnished veneer surfaces" research and development project in collaboration with Akzo Nobel Deco GmbH, the Fraunhofer Research Institution for Polymeric Materials and Composites PYCO, the Bremen Institute for Applied Beam Technology – BIAS and the von Thünen Institute of Wood Technology and Wood Biology. In the course of the project, which has been running since January 2010, is due to end in February 2013 and is funded by the Federal Ministry of Economics and Technology, Lufthansa Technik has succeeded in developing a new varnish system that not only meets the fire protection, health and environmental requirements but satisfies its high quality standards as well.

In the new varnish system, the proportion of solvent has been reduced from 60 percent to 20 without any adverse effect on processing quality. Thanks to a chemical reaction triggered by ultraviolet light, the varnish hardens more quickly so that the subsequent grinding process can begin earlier. The new varnish already satisfies the latest EU directives on the protection of humans and the environment. At the same time the clear varnish has a significantly higher shine than could previously be achieved, thus satisfying the most exacting aspirations of customers.

A patent application has already been filed for the new varnish, which is due to be used for the first time in a customer aircraft, a Boeing 747-8 VIP, in the spring of 2013, directly after the project ends. Thanks to the "Environmentally friendly varnished veneer surfaces" research and development project, Lufthansa Technik has gained a lot of expertise in the area of varnish and processing technologies. By using this globally unique varnish, the company is fully meeting its high aspirations as regards green MRO, employee protection, durability, quality and time and cost efficiency.