10.02 Document Examiner's Lab

Ink Chromatography

Many times a document examiner is asked to determine what type of pen was used to write a document. Ink chromatography is a scientific technique that a document examiner uses to determine the ink used.

This technique is built upon the molecular separation of a substance. Ink is made of different molecules and these molecules will migrate and separate upwards when they are applied to a highly absorbent material like filter paper.

Each molecule's relative mass will determine how far up the filter paper they will move. Once they have stopped moving the molecules will deposit themselves onto the filter paper and will create what is called a chromatographic pattern.

An International Ink Library has been around since the 1920's. The United States Secret Service maintains this library which contains six thousand different types of chromatographic patterns for comparison purposes. Most manufacturers add a unique dye to their inks each year so every year the library must be updated. This also helps to date the "age" of the ink/pen being used.

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Lab

Let's tour a Board Certified Forensic Document Examiner's Lab.

Here you will explore different tools used to analyze documents.

Click on each tab to learn about the different instruments used.

 

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