Forming a unique stochastically branching pattern includes providing a first fluid between a surface of a first substrate and a surface of a second substrate and introducing a second fluid between the surface of the first substrate and the surface of the second substrate. The second fluid is in direct contact with the first fluid at a formation temperature, and a viscosity of the first fluid at the formation temperature exceeds a viscosity of the second fluid at the formation temperature. The first substrate and the second substrate are separated to yield a unique stochastically branching pattern comprising the first fluid on the surface of the first substrate.

Forming a unique stochastically branching pattern includes providing a first fluid between a surface of a first substrate and a surface of a second substrate and introducing a second fluid between the surface of the first substrate and the surface of the second substrate. The second fluid is in direct contact with the first fluid at a formation temperature, and a viscosity of the first fluid at the formation temperature exceeds a viscosity of the second fluid at the formation temperature. The first substrate and the second substrate are separated to yield a unique stochastically branching pattern comprising the first fluid on the surface of the first substrate.

A security feature is presented for a security or value document. The security feature comprises a zinc sulfide luminophore in the form of particles. The zinc sulfide luminophore has the general chemical formula ZnS:Cu.sub.x, M.sub.y, X.sub.z; here, M represents one or more elements from a group comprising the chemical elements Co, In and Ni; X represents one or more elements from a group comprising the halides F, Cl, Br and I; and the following applies: 0<x<0.002 and 0::; y<0.00015 and 0::; z<0.00050. The particles each have cubic phase portions and hexagonal phase portions. When excited by an electrical field, the zinc sulfide luminophore emits a first radiation in the range of the light spectrum between 580 nm and 780 nm. When excited by heating the luminophore to a temperature between 100 C. and 150 C., the zinc sulfide luminophore emits a second radiation in the light spectrum.

A security feature is presented for a security or value document. The security feature comprises a zinc sulfide luminophore in the form of particles. The zinc sulfide luminophore has the general chemical formula ZnS:Cu.sub.x, M.sub.y, X.sub.z; here, M represents one or more elements from a group comprising the chemical elements Co, In and Ni; X represents one or more elements from a group comprising the halides F, Cl, Br and I; and the following applies: 0<x<0.002 and 0::; y<0.00015 and 0::; z<0.00050. The particles each have cubic phase portions and hexagonal phase portions. When excited by an electrical field, the zinc sulfide luminophore emits a first radiation in the range of the light spectrum between 580 nm and 780 nm. When excited by heating the luminophore to a temperature between 100 C. and 150 C., the zinc sulfide luminophore emits a second radiation in the light spectrum.

Making a dendritic identifier includes compressing a drop of liquid between a surface of a stamp and a surface of a substrate, and separating the stamp and the substrate to yield a dendritic identifier on the surface of the substrate.

A security device is provided, comprising one or more surface relief structure(s), each formed of one or more cured material(s), the surface relief structure(s) being disposed on a substantially flat substrate and defining a plurality of raised elements spaced from one another, the raised elements corresponding to elements of an image, whereby the plurality of raised elements varies across the surface relief structure(s) so as to exhibit a multi-tonal version of the image. Methods of manufacturing such devices are also disclosed.

A security device is provided, comprising one or more surface relief structure(s), each formed of one or more cured material(s), the surface relief structure(s) being disposed on a substantially flat substrate and defining a plurality of raised elements spaced from one another, the raised elements corresponding to elements of an image, whereby the plurality of raised elements varies across the surface relief structure(s) so as to exhibit a multi-tonal version of the image. Methods of manufacturing such devices are also disclosed.

Making a dendritic identifier includes compressing a drop of liquid between a surface of a stamp and a surface of a substrate, and separating the stamp and the substrate to yield a dendritic identifier on the surface of the substrate.

A security element for a value document includes: a first concealed motif region having a first luminescence layer with at least one first excitation wavelength in the UV-A range; and a second concealed motif region having a second luminescence layer with at least one second excitation wavelength in the UV-A range that is different from the at least one first excitation wavelength.

A security element for a value document includes: a first concealed motif region having a first luminescence layer with at least one first excitation wavelength in the UV-A range; and a second concealed motif region having a second luminescence layer with at least one second excitation wavelength in the UV-A range that is different from the at least one first excitation wavelength.