METHOD OF DETERMINING AGE OF STROKES OF COLOURING MATTERS OF DETAILS OF DOCUMENTS ON DYNAMICS OF THEIR DISCOLOURATION Russian patent published in 2014 - IPC G01N21/31 

FIELD: printing.

SUBSTANCE: invention relates to documentation expertise and can be used in the forensic, criminalistics and judicial practice in technical expertise of determining the true execution time of details of documents made with ballpoint pen ink, ink for capillary, gel, fountain, "roller" type pens, ink for watercolour pens and ink jet type printers, colouring matters of printers of a matrix type, typewriters, and the impressions of seals (stamps) and other materials of writing. The method of determining the age of strokes of the colouring matters of the details of the documents is that the colouring matter is selected for a control stroke and the control stroke is created, the samples are obtained of the test stroke and the control stroke, which execution date is known. Then the samples are extracted in a solvent and the total colour difference is determined and the difference in lightness for the test and the control strokes with respect to the solvent, receiving the samples of the control and test strokes is repeated at least once in at least one time interval, as well as their extraction in the solvent and determining the total colour difference and the difference in lightness of the test and control strokes, and relative remoteness of the application of the test stroke is determined. At that obtaining the samples of the test and control strokes is carried out by making impressions of the test and control strokes on segments of an absorbent material wetted with a solvent. And as the absorbent material used is cellulose acetate, and as the solvent - methanol. In addition, selection of the colouring matter for the control stroke is preferably carried out by identifying the type of the writing material of the document, measuring the spectral characteristic of the colouring matter of the details of the document, and selection of the colouring matter of the same material type of writing as the colouring matter of the details of the document, and with the spectral characteristics most similar to the spectral characteristic of the colouring matter of the details of the document.

EFFECT: providing the possibility of determining the age of strokes without violation of integrity of the document with minimal changes to the appearance of the document.

2 cl, 4 dwg, 2 tbl