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Opinions of ink dating chemists, both government and private, differ on the reliability of the above described ink aging methods.Therefore, before applying any of these methods to actual case work the author conducted an independent evaluation of the reliability of the R-Ratio, Percent Extraction, Dye-Ratio and Accelerated Aging techniques for estimating the age of writing ink on documents.Six experiments were conducted using the following procedures. Samples of the known and questioned ink are removed from the paper using a hollow needle punch with a plunger to push the sample out of the needle. Inject 20-30 microliters of a weak solvent like n-butanol, into the vial and make sure all the plugs are covered. 4 microliter aliquots are then taken using a volumetric pipette after stirring by rotating the vial five times before such aliquots are taken and spotted on a Merck HPTLC plate. After the desired aliquots have been taken at the desired times, usually 30 seconds, 90 seconds, 3 minutes and 10 minutes, 10 microliters of Benzyl Alcohol, or another strong solvent is then added and allowed to extract for 5 minutes. Another 4 microliters aliquot is taken of this solution and spotted on the TCL plate as well. The relative intensities of all 5 spots are calculated using a Densitometer and then using the following formulas: R-Ratios Percent Extraction 10 minute extraction value Benzyl Alcohol value Percent extraction can also be calculated at 30, 90, and 120 second times to obtain a percent extraction curve.Caution should be taken to not get any combination from such things as other inks, inks from the opposite side of the document, or printed stamps. This will normalize all the values and make them mass independent.Also, make sure to leave at least 1/2 of the ink so testing can be duplicated by another expert. These will not be the exact values for rate or percent extractions, but all numbers are treated the same and can be compared without the correction factor for adding or removing volumes.
It can, however, be done if desired, but has no bearing on the results.