METHOD OF DETEMINING DOCUMENT CREATION TIME FROM BALL-POINT PEN MARKS OR STAMP INK IMPRINTS Russian patent published in 2011 - IPC G01N21/31 

FIELD: physics.

SUBSTANCE: specimen cut-offs are extracted in a solvent. The cut-offs used are those of the analysed and control mark, whose date of creation is known. Full colour difference of the analysed and control mark is determined in accordance with the ISO 7724-1:1984, with contrast of not less than two times. Points determined by numerical values of the colour difference between samples, obtained from the first and second control marks, are positioned on a semilogarithmic coordinate grid. Points of the full colour difference of the specimen are positioned on that grid during the starting and subsequent days of analysis. The date of making the analysed mark is determined based on the known date of making the control mark.

EFFECT: high accuracy of determining the actual date of creation of the document.