FORS-2107EL Study Guide - Quiz Guide: Potassium Ferrocyanide, Invisible Ink, Glycol Ethers
27 Jun 2018
School
Department
Course
Professor
Questioned Document Quiz Review
-To analyze documents, it is necessary to compare exemplars (known) to questioned
documents
-Watermarks normally change periodically, so this can help in detecting age of a document
-Ink is a coloured liquid made of of different substances, in a solvent, ex. ballpoint pens are
organic dyes in a solvent like glycol or glycol ether
-Ink can be distinguished from one another using chromatography, and age of the ink
-Iron gallontannate oxidizes in air to change colour, this depends on the pH of the ink, the
amount of exposure to light, temperature, and composition of paper involved, this is why
archival quality writing are acid free, the more acidic, the higher the chances of oxidation over
time
-Inks containing carbon black will not change with age
-Pencil lead is a combination of graphite, clay, and kaolin (binder)
-The more carbon the softer the pencil will be
-The more clay the harder the pencil will be
-Typewritten documents can be traced back to machine that produced it, or to a specific
machine by looking like features like chip out of a letter or an individual letter that is raised
higher then the others, the older the machine, the easier it is to individualize
-Welders often suffer from shaky hands that get worse with time
-Handwriting is the product of 2 thing, the physical movement of the hand and the
subconscious activity of the mind direction the hand
-When forgery occurs, line quality can lack smoothness and there will be deviations in size,
portions of letter, slant of letters, curves, and spacing
-Erasures can be mechanical (by physically rubbing something in an abrasive manor) or
chemical (ink eradicators)
-Physical eradicators: which can disturb the fibres that can be seen under microscope or
strong light, iodine can be used to test this as iodine will attach to the rough spots to leave
a brown stain
-Chemical eradicators: usually sodium hypochloride (bleach), here ink can become invisible
to the naked eye but still visible under UV light
-Invisible ink can be made of many things (milk, lemon juice, body fluids), that can be heated
gently to produce a brownish colour to the writing
-Invisible ink can also be made of different chemical compounds, NaOH can be seen with
phenolphthalein, Iron III sulphate can be seen with potassium ferrocyanide, and fluorescent
ink will be visible under UV light
-Water can also be used as invisible ink, as it will disturb the fibres and can be seen with
iodine fuming
-Indentations can be seen by going over the area with pencil, which will colour the paper but
not the indentations
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
To analyze documents, it is necessary to compare exemplars (known) to questioned documents. Watermarks normally change periodically, so this can help in detecting age of a document. Ink is a coloured liquid made of of different substances, in a solvent, ex. ballpoint pens are organic dyes in a solvent like glycol or glycol ether. Ink can be distinguished from one another using chromatography, and age of the ink. Inks containing carbon black will not change with age. Pencil lead is a combination of graphite, clay, and kaolin (binder) The more carbon the softer the pencil will be. The more clay the harder the pencil will be. Welders often suffer from shaky hands that get worse with time. Handwriting is the product of 2 thing, the physical movement of the hand and the subconscious activity of the mind direction the hand.
