Ink age dating
This method can be useful only when the inks are still drying (up to six years but more likely one to two years) as solubility changes cease once ink has completely dried.
Additionally, as resins in inks harden, which begins on deposit, their solubility diminishes and importantly they trap colourants.
Relative age comparison tests performed on inks of the same formula and written on the same type of paper with the same storage conditions (performed by measuring changing solubility properties of inks) can estimate how long inks have been written on paper.
This is done by: (1) comparing the rates and extents of extraction of questioned and known dated inks in organic solvents by thin-layer chromatography (TLC) densitometry; (2) comparing changes in dye concentrations by TLC and TLC densitometry; and (3) comparing the volatile ink components by gas chro-matography-mass spectrometry (GC-MS).
Other ink entries are not necessary for comparison. Aginsky has developed the SET as a result of many years of research of the ink aging methodology developed and published by Dr. For example, if the questioned document’s date precedes the manufacturing date for the ink used to sign the document, it is established that the document could not have been signed on the date it bears. Such intra-comparisons of inks may reveal that the questioned entries were not written contemporaneously with the other entries in the file (document). – The examination’s purpose is to assess whether the use of various inks on the document(s) fits a pattern that is either consistent with the dates appearing on the document(s) or indicates preparation "at one time" (during a short period of time). Paper folds – It is often possible to determine whether an ink line that intersects a paper fold was written before or after the paper was folded.
Offset marks – When two pieces of paper are pressed together, marks such as writing (and printing) may be transferred from one to another.
These two ink aging methods are the Sequential Extraction Technique (SET) and Solvent Loss Ratio Method (SLRM).
The SET and SLRM measure certain ink aging parameters of ink that decrease as ink ages on paper. To date, the SET is the only ink aging method that has shown its reliability through outside proficiency testing using “blind” samples (outside proficiency tests in 1995, 2001, and 2011). Ink Availability Approach The second ink dating approach analyzes the chemical composition of inks on a contested document with the aim to determine whether these inks (as well as other materials used to produce the document – paper, inkjet printing ink, toner, stamp pad ink, etc.) were commercially available on or prior to the date appearing on the document. – The examination’s purpose is to assess whether the entries being compared were produced with the ink of the same composition or with different inks (pens). The order of execution of certain elements of a document Writing ink sequencing – Examining intersections (areas where two or more pen lines cross) to determine the order of writing (it may prove that a particular entry was added at a later time) Sequencing of indented impressions and writings – Examining intersections (areas where the visible ink lines cross the indentations) may determine the order of writing and thus prove that a particular entry was added at a later time.
Evaporation of ink solvents begins in the first few minutes during which time there is a rapid and significant loss.This article describes state of the art procedures for the chemical and physical comparison, identification and dating of inks on questioned documents.Knowledge of the composition of inks is necessary to understand the reasons for the various methods used to analyze inks.Establishing the approximate age of an ink entry from a questioned document is often a complicated task and a controversial issue in forensic sciences.Among the existing approaches, the analysis of solvents in ballpoint inks may be a useful parameter for determining the age of ink on paper.