Digital Outback Photo
- Photography using Digital SLRs


 

Printing Insights #042

A Note on OBA (Optical Brightening Agents)

note Uwe Steinmueller

 
 
 

 

We are struggling for quite a time how to talk and judge the existence of OBA (Optical Brightening Agents). It is certain that:

  • OBA fade (especially under UV light)
  • Not all papers with OBA fade at the same speed (own tests and tests by other sources)
  • Bright white papers with allowing high contrast need OBA
  • OBA can be applied to the coating or the paper
  • Some papers use more OBAs than others (means the difference between the paper with and without OBAs can vary)

A press release we received today by Hahnemuehle USA on this issue is the reason to write this note as we think they have a point. What we write here is our opinion and not influenced by this press release but still we think the press release is not that off the mark. Here are some quotes from this press release that we would like to comment on.

Note: During our conversion of the press release to PDF we lost the link to "Library of Congress Standard for Permanent Paper"

"OBAs are white or colorless compounds that work by converting ultraviolet light into visible light, thereby making the paper appear brighter or whiter. They do not change the color of the paper; they only fool the eye into seeing a whiter color. After being exposed to UV rays for a long period of time, OBAs will begin to lose their fluorescent quality, leaving only the natural base color."

This seems to be an accurate description on what OBA are and what they do. Because they all fade probably faster than the papers fade (yellow) it is better to use papers without OBAs. But there is a big if: If you want to accept the natural slightly yellow of papers without any OBAs. This is a pure artistic and pragmatic decision.

"So the claim that OBAs cause paper to yellow or reduce its permanence is simply wrong. Eventually, the perceived color of the paper will revert to the same base color as papers without; but initially, OBAs allow a much brighter base. It is not yet known how long the reversion to natural might take. We do know that it is not an immediate thing; it could take as many as 50 years (even longer if the artist takes measures to protect the image from the effects of UV rays.) But the point to remember is that the paper will end up the same color as it would have if OBAs were not used."

This is a point that only scientists can verify. The question is whether there is a side effect of OBAs besides just fading away over time.

"Consider that virtually all silver halide papers used in darkroom photography contained OBAs. Artists who wanted a bright white base simply accepted the fact that there would be a slight change over a long period of time. In fact, many photographers and collectors find this “mature” look desirable. At Hahnemühle, we strongly feel that to provide the paper base color and print color where the artist wants it for their lifetime is better than having it wrong from the beginning."

We always suspected that classic silver halide papers also contained quite a bit of OBAs. In the art world this seems to be accepted. The real question is how fast the papers with OBA will yellow and how bad the photos will look if they get back to the natural base color of the papers.

Note: "Yellow" in this context means that the paper looks relatively more yellow (or warm) when the OBAs are gone compared to the paper with OBAs present. This is an entirely different effect than the yellowing of the paper substrate itself

Conclusion

If you find that natural papers without OBAs work for your images then this would be a safe bet. Otherwise live with the fact that your papers will yellow over time (and some seem to do this faster than others). You as the photographer have the choice to use papers with and without OBAs. There is no silver bullet.

We find the press release by Hahnemuehle very helpful because it opens up a more useful discussion on OBAs.


6/20/2006 Visualize OBAs with the BabelColor White Target

When we first published this article we became aware of this excellent paper "How to use a white Target to identify UV-enhanced paper" by BabelColor. In the meantime we got the BabelColor White Target and used it in the following test shot:


BabelColor White Target

Check the image and you find the following:

  • The white on the target is pretty neutral
  • The target seems to look yellow because the paper used in this paper contains quite strong OBAs which make the paper look more blue (there are many papers out there with this characteristics).

The Babel Color White Target is a useful tool to evaluate papers for OBAs. There are many more applications where a maximum white target comes in handy: controlling the exposure for bright highlights and performing white balance for digital images.

 


 

Please share your opinion in our printing news group.

Resources

"How to use a white Target to identify UV-enhanced paper" by BabelColor

Comments

Juergen Gulbins

"Paradox: If you protect the paper against UV using UV filtering glass then at the same time you also minimize the effect of the OBAs." (6/6/2006)

From our forums (6/6/2006)

"OBAs are a major problem with paper/printer profiling."

From comments at "The Online Photographer" (6/6/2006)

Because different light sources have a different intensity of UV prints may also show more metamerism.

Note by George Barr on his blog (6/7/2006)

 

 


This is one of the many techniques we will teach during the 2006 Summit. We will also work with you 1 on 1 and help you with your own images and with how to use this technique, and many others, in your own work. Click here to read a detailed description of the 2006 Digital Fine Art Summit. Joseph Holmes will join the Summit 2006 as a guest instructor means you can ask this world class printing expert directly.

About the Fourth Annual Photography & Fine Art Printing Summit

The 4th Photography & Fine Art Printing Summit will take place November 10th to 13th, 2006, in Page, Arizona. Seats are limited. In addition to studying color management and color spaces, we will also do field photography in stunning locations such as Antelope Canyon, Lake Powell and Horseshoe Bend, as well as study Raw conversion, Photoshop processing, image optimization, printing. We will also conduct print reviews of your work created during the Summit. Find out all the details of this unique learning and photographing opportunity on the 2006 Summit page.

 

 
 
 
 
 

 

For Comments post in our News Group

2000-2007 Digital Outback Photo