Ultraviolet Reflectivity in Ink Jet Papers

2020

Rating Key
1 = low reflectivity of UV (high OBAs)
10 = high reflectivity of UV (no OBAs)

Introduction
Many ink jet papers include optical brightening agents — or OBAs — which are chemicals that react with ultraviolet light and make the paper appear brighter and cooler. In general, papers with OBAs absorb more UV light than papers without OBAs. Barring either advanced chemical analysis or confirmation from the manufacturers, there is not always an easy way to know whether a given paper has OBAs. Therefore the purpose of this research is to independently assess a comprehensive list of currently available papers as a guide for artists, designers, and anyone concerned with the archival properties of ink jet paper.

Methodology
In this experiment, 153 different ink jet papers were exposed to an ultraviolet LED and the reflected UV light was measured with a spectrometer. Peak intensities of these measurements where normalized to a scale of 1 – 10, with 1 being very low UV reflectivity and 10 being very high UV reflectivity. The results suggest that papers with a UV reflectivity rating of approximately 7 or higher contain little or no OBAs. Below a rating of approximately 7, however, the presence of OBAs appears stronger and stronger as the rating approaches 1.

Background
There is concern that OBAs may breakdown over time and shift the appearance of the printed image. So while OBAs might be useful for temporary projects, there is good reason to be suspicious of their longterm viability. For creatives who need their work to last for many years in permanent collections, archives, etc., being aware of the presence of OBAs is an important consideration.

Disclosure
This dataset is an art project, and while every effort was made to operate under controlled conditions, the interpretation of these data involves subjectivity. The peak intensity measurements were normalized to a 10-point scale to make the information more accessible for end users, however, it is important to remember that there are papers with no OBAs whose rating is lower that 10. The rating simply corresponds to the relative intensity of reflected UV light, not the explicit presence of OBAs, per se. Other factors may affect these measurements such as the following: paper surface, the presence of other chemicals, location of OBAs in the superficial coating or paper pulp itself. More research would be required to isolate these variables and determine more precisely the presence and effect of OBAs on the printed image.

Credits
Concept and Research by Andy Mattern Programming by Mark Morgan