NCJ Number
136864
Journal
Journal of Forensic Sciences Volume: 37 Issue: 3 Dated: (May 1992) Pages: 738-749
Date Published
1992
Length
12 pages
Annotation
Various blue and black inks are shown to change their transmission spectra by applying pressure and smearing them as deposits on glass slides.
Abstract
The experimental procedure employed a computerized microspectrophotometer. Ten blue and 10 black pens were examined; all pen inks were deposited on glass slides by writing directly on the glass slides or by making many strokes with a pen on a polyethylene plastic sheet and pressing it on a slide. Smearing of ink deposits was carried out using an engraving tool. The sample inks practically obeyed the Beer-Lambert law (good reproducibility) when their traces on white or brown paper were smeared on glass slides. The spectra reproducibility obtained by the method of mounting inked fibers in Permount was significantly less, especially in the case of black inks on white or brown paper and in the case of blue inks on brown paper. In the case of some blue and black inks, the spectra of smeared inked fibers differed from the spectra of unsmeared ink deposits on glass. Dissolving smeared ink deposits on slides by solvents like methyl or ethyl cellosolve and drying usually restored the original spectra. It is concluded that the transmission spectra of small samples of inked paper fibers smeared on glass slides resemble the spectra of smeared ink deposits and are more reproducible than the spectra of inked fibers in a mounting medium. This advantage is especially significant in the case of examining ink traces on tinted paper. 16 references, 2 tables, and 12 figures (Author abstract modified)