I utilize a variety of laboratory instruments in my work. For example, a simple loupe (magnifier), is often used to enlarge fine details in writing or printed text. If further magnification is used, a microscope is very useful in examining printing processes, ink strokes, security features and other document features.
Another instrument of value in resolving cases is an instrument designed to recover indented writing. Think of having two or more pages stacked together. As you write on the top page, indentations of the writing are made onto the following page(s) due to pen pressure. The paper fiber disturbances are targeted by the instrument. One such device, called an Electrostatic Detection Apparatus (ESDA), is manufactured by Foster and Freeman. Processing a document on an ESDA or similar instrument will not harm or mark a document.
Obliterations or alterations often involve inks different from the original entries. A sophisticated instrument using infrared filters and ultraviolet light is used by forensic document examiners for such examinations. Foster and Freeman makes a Video Spectral Comparator (VSC), allowing ink comparisons and many other types of document analysis.
Ink dating is not a testing process common to most document examiners, particularly in private laboratories. The chemical analysis for ink dating is a very specialized field. If ink dating would be of benefit to a case, a document examiner will refer the client to an ink chemist.