SSBI SSF 46-15: Pressure Marking of Prepainted Sheet Steel

Pressure marking, also known as pressure mottling or imprinting, is an uneven or irregular gloss pattern on the face of a prepainted sheet steel. The photograph in Figure 1 shows what pressure marking looks like. The mottled appearance takes place when the gloss components in the prepainted top coat are compressed or flattened during the manufacturing and coiling process. The condition is more prevalent on dark colours and high gloss products. Pressure marking is also typically noted in the centre of the strip where the coiled product is under the most pressure