EN1186-1: 9.3 However, the experimentation can be avoided in the case of materials with a thickness greater than 0,5 mm because it is conventionally agreed, except for plasticized polymers and multi-layer materials where the food contact surfaces are different, that for these materials the calculation shall take into account the total surface exposed? If the area of the cut edges of the test specimen exceeds 10 % of the measured area of the sample then this area has to be included in the calculation of the surface area used in the calculation of overall migration.