In an excellent article published in the July, 2009 issue of Sign & Digital Graphics Magazine, inkjet-printing-technology consultant Dr. Ray Work addresses some of the concerns surrounding the use of optical brightening agents (OBAs) in inkjet media for fine-art reproductions and long-lasting photo prints.
Dr. Work holds a Ph.D. in physical organic chemistry and worked in research and development positions at DuPont for more than 28 years. He wrote the article to clarify some points for those who have been told that only OBA-free media are truly archival. He cites scientific information and third-party laboratory data that can “put to rest the fear that OBAs are evil and must be avoided.”
In the article, Dr. Work defines OBAs as organic dyestuffs that absorb ultraviolet light and re-emit or reflect that light in the blue part of the visible spectrum. He explains that OBAs must be used if you want a white substrate on which to print. And, to achieve the maximum color saturation and color gamut from the printer’s inks, a bright media is required.
Dr. Work notes that OBAs have been used for many years at low levels to whiten and brighten paper and canvas. He points out that the fiber papers Ansel Adams used to make his prints in the 1970s contained OBAs.
“With exposure to light and heat, over time the OBAs can lose their ability to fluoresce and add the blue light to the reflectance spectrum,” writes Dr. Work. “The result is that the media will revert to the original color of the materials that make up the media and its coatings. It is unlikely that these OBAs will turn yellow. When they decompose, they become colorless.”
He adds that, “Choice of the type of OBA and the amount used along with its location in the final print affect the rate at which this occurs. In our modern inkjet fine-art papers and canvases, the OBAs chosen, along with high-quality paper, canvas substrates and coating materials result in excellent print longevity with little risk of yellowing due to the OBAs fading over the life of the print. In addition, they do not interact with the pigments in the inkjet inks provided by the printer manufacturers.”
In the article, Dr. Work notes that Wilhelm Imaging Research has completed new evaluations of the display life of art papers and canvases from three major providers of wide-format inkjet printers with water-based pigment inks. He says, “There is no trend in this data that suggests the presence of OBAs reduces longevity.”
Click here to download a PDF of Dr. Work’s full article, entitled To Brighten or Not to Brighten. Thanks to Sign & Digital Graphics for granting LexJet permission to make this PDF available. (www.SDGmag.com)
Dr. Work heads Work Associates, a consultant firm specializing in inkjet printing technologies, applications, and markets. He writes the Think Ink column for Sign & Digital Graphics magazine.