Infra-red responsive fingerprint composition and method of making
US4226740A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 9, 1979 |
| Grant date | Oct 7, 1980 |
| Priority date | — |
| Expiry date | Feb 9, 1999 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61B5/1172
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
An infra-red responsive fingerprint composition and method for manufacturing by sifting and mixing a minor proportion of finely divided carbon black (50 to 75 millimicrons) and a major proportion of infra-red responsive finely divided pigments containing milori blue (250 to 400 mesh), manganese dioxide (300 to 400 mesh), aluminum powder (1 to 75 microns) and mica (10 to 20 microns). A small amount of gum arabic as binder is included to facilitate adhesion of the print powder to latent prints. On white surfaces the fingerprint powder is black. On dark surfaces the fingerprint powder is brightly reflective so that when lifted or transferred to a white backing the color changes from brightly reflective to black. The reflective color becomes even more vivid under infra-red. Storage is preferably in tightly sealed containers in the presence of dessicant capsules to prevent moisture pick-up and caking of the gum arabic.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.