Drawbacks with liquid coating and overlays on MDF finishing

The two most widely used finishing techniques for MDF boards are:

• Liquid coatings
• Paper-based laminates (mostly melamine impregnated) and
• Thermoplastic foils (PVC, ABS, polyolefine-based)

A range of surface appearances and qualities can be obtained with these technologies. However, there can be some drawbacks with both liquid coating systems and overlays, which can be overcome by use of UV powder coating.

When using liquid coatings, normally a multi-coat system with interlayer sanding is required to achieve attractive finishes. This means that labor, maintenance, energy and space requirements are important cost factors. Also, depending on the type of liquid coating system used, waste disposal costs can be quite high. Environmental pressures will oblige companies to replace conventional solventborne paints by alternatives in the near future.

Paper-based laminates are characterized by their excellent surface properties such as wear, heat and chemical resistance. The development of new presses allows the quick and efficient lamination of panels. However, for the finishing of profiled or shaped MDF boards, the use of this type of laminate is excluded because of lack of flexibility.

The use of thermoplastic foil, however, can overcome this problem. The resistance of these types of overlay is considered to be lower than that of paper-based laminates and the cost of the better qualities is known to be quite high. The costs of the glue and of the waste produced by non-matching foils should also be taken into account.