| 摘要 |
A layer including magnetizable material and a pigment of lower magnetic susceptibility in a settable coat are subjected to a selectively applied magnetic field gradient in the layer while the coat is unset to cause the magnetizable material to selectively break through the pigment. The coat is then set, while the materials remain in position, to produce a detectable pigmentation pattern of said break-through. The magnetic material may itself be a pigment and break-through the first one to produce an eye-visible pattern. The magnetizable material forms a magnetic susceptibility distribution pattern equivalent to the pigment break-through pattern. The layer having the pigment pattern may be used as a security feature in, e.g. a security document, both the patterns being alterable, once the coating has set, only by damage to the layer. |
