Abstract: A microstructure area (201) providing a first diffractive visual effect is produced on the surface layer (240) of a paper or cardboard substrate (230) of a product (200). In addition, a bulge (206) or a recess (207) having a second microstructure area (202) is produced on the surface layer (240), wherein a doubly curved portion (203) is located between the first (201) and the second (202) microstructure areas. Said combination of the bulge (206)/recess (207), microstructure areas (201, 202) and doubly curved portion (203) makes counterfeiting of the product (200) difficult and provides a special visual effect.

Abstract: The invention relates to an electrical and/or optical temperature detector/indicator based on conductive polymers, said detector/indicator being suitably used in such packages for products, the temperature changes of which need to be monitored.