What are optical brighteners? Optical brighteners, or optical brightening agents (OBAs), are chemicals that are added into certain fine art papers in order to help them appear “whiter.”
How do OBAs work? The chemicals added to the paper take invisible ultraviolet light and cause it to re-emit as light we are able to see, in a process of fluorescence. This then allows us to see an incredibly white paper because our eyes are perceiving both the white of the paper and the light being emitted by the chemicals in the paper.
Samples of Fine Art Media
© Cottontail Press
So what’s the downside? While OBAs are excellent at producing a brilliant white paper, there are a couple of things you may want to consider before printing your high quality images onto papers that contain the chemical.
The first is colour profiling. During the conversion process of the chemicals in the paper, the ultraviolet light is emitted in the blue spectrum – or fluoresce – at a point that is just barely within our ability to see. While our eyes see this as a brighter, blueish white – a spectrophotometer used to read color on paper will only see this as a different form of blue. That is why profiles made with paper using a lot of optical brighteners can end up printing out images that have a yellow tint to them. The profile is trying to correct for what it identifies as a large amount of blue in the paper.
The second thing to consider is the longevity of your prints. Giclée printing is special because it uses aqueous pigment inks together with fine art papers to produce archival, museum-grade prints. If your print standards require this type of archival permanence, you will need to examine the amount of OBAs in your fine art paper. Since OBAs are not permanent, papers that contain them may dull down overtime and the image will be less bright than when you first viewed it. Of course, this can vary depending on the amount of optical brighteners added to the paper and how much exposure the paper has to UV light.
“When long-term image permanence is an important consideration – or may eventually become an important consideration – fluorescent brighteners should be avoided where possible.”
Why would I use papers containing OBAs? Before you panic, keep in mind that OBAs are a very reasonable way to get more white onto a paper. Without them, some of our papers would look rather bleak, given the natural color of wood pulp and cotton. This leads us to a big advantage of papers containing OBAs: colour gamut and tonal range. The bright white paper base allows the maximum colour gamut and black density of the printed image to be reproduced.
What should I choose? The decision about whether to use inkjet papers with OBAs is entirely at your discretion. We have several different paper types available to choose from, some containing OBAs and some OBA-free. If you are still concerned or have questions about which paper to choose for your giclée print, please feel free to contact us. We are happy to answer any question you may have!