Security label, to give a visual indication of magnetic field effects, has colored metal particles between carrier and semi-permeable layers covered by a transparent protective layer to give a view of attracted particles

摘要

The security label (11), to give a visual indication of exposure to magnetic effects, has a layered structure (12) containing metal particles responsive to magnetism. The structure has a carrier layer (14) supporting a semi-permeable layer (21) with colored metal particles (18) between them. The semi-permeable layer is covered by a transparent protective layer (24), so that particles drawn through the semi-permeable layer by magnetism are visible.