Optical Brightening Agent (OBA)
Definition
A fluorescent compound added to paper pulp or coatings that absorbs UV-A radiation and re-emits it as visible blue light, making paper appear whiter; introduced commercially from approximately 1949-1953, so strong OBA fluorescence establishes a post-1950s manufacture date.
- What OBAs do
- Absorb UV light and re-emit as visible blue light, making paper appear whiter
- Commercial introduction
- Approximately 1949-1953
- Forensic indicator
- Formulation varies between paper batches, making OBA patterns useful for detecting page substitution
Common questions
What exactly are optical brightening agents, and why are they in paper?+
OBAs are fluorescent compounds mixed into paper during manufacturing to make it look whiter and brighter. They absorb ultraviolet light and re-emit it as visible blue light, which tricks the eye into seeing the paper as whiter than it actually is.
How can OBA fluorescence help detect fake or substituted pages?+
Different paper batches have different OBA formulations. By examining how paper fluoresces under UV light, a document examiner can determine if a page belongs to the original batch or was substituted from a different source.
What does strong OBA fluorescence tell you about when paper was made?+
Strong OBA fluorescence indicates the paper was manufactured after the 1950s, since commercial OBA additives were introduced around 1949-1953. Older papers typically show little to no OBA fluorescence.
Related terms
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- ENFSI Document and Handwriting Working Group
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Explained in these topics
- Detection Methods: Oblique, Transmitted, UV, IR and the VSCFluorescent whitening agents added to paper stock during manufacture; they absorb UV and re-emit in the blue-visible range. Their specific formulation varies b...
- Ink Dating and Paper Examination: Fibres, Watermarks, BrightenersA fluorescent compound added to paper pulp or coatings that absorbs UV-A radiation and re-emits it as visible blue light, making paper appear whiter; introduce...