OBA or FWA good or bad? UV-cut or not?

[nrdlnd]

Hi,

I'm new to printing but I'm trying to learn with a rather fast pace. First selecting papers. There are a lot of good papers to print on. The more affordable papers ar the RC-papers. Everyone of them contain a lot of OBA (optical brightening agents) or FWA (fluorescent whitening agents). The less affordable papers (or more expensive) the so called "Fine Art" papers do or do not contain these whitening chemicals. These chemicals are made by big and well known companies such as Dow Chemicals and CIBA. They are made with highly toxical substances but there isn't well known how toxic the end products are especially for the environment. They exist all around in for example toilet paper (not all), office papers and in photographic material (and have been used even during the black&white era in photographic papers). There function is to reflect unvisible UV-light to visible blue light that makes the paper to look whiter.

What have been discussed about OBA/FWA is about the longevity of a print. There seems to be no easy answer about that as som RC-prints have a good longevity. RC-papers have always OBA. It could be that the RC-coating protects from the environment. I leave this question about the longevity behind.

If I want to be a more advanced printer and also use third party inks I think there is a necessity to learn to profile papers. One of the most advanced programs for doing this is Argyll CMS. For this you need a good spectrophotometer even if I think some colorimeters are useable to some degree. Some of the meters have a so called UV-cut filter some not. The Colormunki has UV-cut the i1 Pro can be with or without and the i1 Pro2 I think can be both. When you profile a paper the UV-cut meters will give a fixed degree of compensation for the OBA in the paper but not for different amount of OBA:s. They will not give correct readings for non-OBA papers. The meters without OBA-cut filters will give correct readings for papers without OBA but may need correction in software for OBA-papers. The big problem is that the correction for an OBA-paper can only be done for a certain viewing condition to give a correct color rendition (for example the standardized D50) and it must be different for different amounts of OBA in the papers.

With all these knowledge of the problems with OBA:s in photographic papers I think there should be an absolut no to it's use in photography especially when you want to deal with correct colour under different viewing conditions. Why? Because the colours look different under different colour temperatures. OBA-papers can only be corrected to look correct in one defined colour temperature. The eye can adapt but not in this case as the rendition is corrupted.

After this rather long back ground writing I want to ask if you people completely avoid these papers containing OBA (I know they shouldn't exist but for only very specialized uses) or how do you deal with them? How do you use FWA-compensation in ArgylCMS?

Per

 

[Paul Verizzo]

Other than the difference in perception due to variance between daylight and other sources, I have a hell of a lot more important things to worry about that OBA's. Especially since most paper use them to some degree or another.

People like white papers.

 

[Roy Sletcher]

...and not all prints have to last forever.

I think I understand your point. But! in the final analysis you pay your money and make your choice.

RS

 

[3dogs]

First up when purchasing photo papers I avoid OBA papers altogether.
Reason, followed a thread on DPReview, many reported significant deterioration when these papers are exposed to direct daylight. Now given that the posts were not verifiable etc. I take them as a guide only. However, I still avoid them altogether.

BUT
I use a plain paper for a consumable when processing images to print e.g. composits, panos etc. Im sure they are loaded with OBA's, but inexpensive and therefore ideal as a throw away item.

Hope that helps.

 

[Ink stained Fingers]

'OBA-papers can only be corrected to look correct in one defined colour temperature. The eye can adapt but not in this case as the rendition is corrupted.'

It is not so much the color temperature of visible light for which OBA papers would need to be corrected but for the lighting/viewing conditions, whether this light contains UV spectral components which excite the OBAs in the paper. Look to the adjustment options e.g. in the i1Profiler software, you have to select a particular type of UV illumination, different types of fluorescent lamps - Neon, Xenon, Natrium etc have different types of spectra which need to be considered. Or you just cut all UV, place your prints under glass or view them under bulb light only, not even halogen lamps which emit residual UV. Or you don't care so much, it all depends whether you print for an exhibition or a museum, and your images will viewed at for days or months or years. OBAs may deteriorate over time and turn yellow, but after 20 years other parts of the paper may become brittle like the PE coating etc. The Wilhelm Research Institute WRI has done extensive work over a long time for image conservation, their reports tell you what is good or bad for your prints.

 

[Emulator]

If you obtain one of these UV torches:

http://www.amazon.co.uk/s/ref=nb_sb_noss_1/279-4541731-8234060?url=search-alias=aps&field-keywords=UV torches

You can shine it on practically any paper and find it has OBA added. The exception is surprisingly rare.

The other issue to think about is how the so called UV cut is achieved. Is it by using a UV filter or is it by using an internal light source that does not emit UV light content. The result may be different.

 

[nrdlnd]

I have a lamp like this: http://www.teknikmagasinet.se/produkter/maskerad-o-party/disco/blacklight-lagenergilampa
I've been using it and the RC-paper SIHL Lustre glows a lot and regular document papers even more. the Sihl paper is difficult to calibrate. It looks ok in incandenscent light without UV but not in daylight. The Canson Platine Fibre Rag seems to have almost no OBA, the Baryta Photographique little that seems to be without much consequence, the Hahnemühle copy of Gold Fibre Silk, Photo Silk Baryta seems to have more. Spectrum Viz http://www.pigment-print.com/spectralplots/spectrumviz_1.htm is very useful. For quality printing I don't understand the meaning to put OBA in the material! When I brew my coffe I use the brown cheaper filters without OBA. This is a big industry trying to fool us that everything white should be bright white! Of course it's important to have it in the toilet paper so you can see the sh!t!

 

[Roy Sletcher]

For quality printing I don't understand the meaning to put OBA in the material! When I brew my coffe I use the brown cheaper filters without OBA. This is a big industry trying to fool us that everything white should be bright white! Of course it's important to have it in the toilet paper so you can see the sh!t!

Don't forget the natural colour of cellulose pulp for paper-making is a dirty brown, so some form of whitening is essential if the final sheet is to be anything other than a dirty brown. - The sh!t analogy above is not wasted.

The OBA phobia is a somewhat recent thing in the photo paper industry. It replaces many of the traditional and more gentle whitening agents. I suspect because it is cheaper. I think the current general assumption is that all quality papers will now be acid and lignin free.

For the OBA papers lot may depend on where in the paper the OBAs reside and in what quantities. They could be added to the pulp, the sizing agent, the baryta or resin coat, the inkjet receptive coat, or any combination.

The problem with adding a lot of OBA content to a paper is the spectral reflectance curve will be totally skewed. The paper would no longer look white. With excessive OBA content it could even look blue - at least under any lighting with a significant UV content.

OBA`s eventually breakdown and degrade and sometimes this causes the paper color to change much faster than the inks fade. From the comments I have read this isn’t apparent with Wilhelm’s testing methodology, but is obvious under Aardenburg’s methodology.

Just some observations. Feel free to comment at will

RS

 

[Emulator]

Have you tried it on urine?

 

[PeterBJ]

UV lights are also advertised for travellers to check cleanliness of hotel rooms. You can also check if your pet is well behaved.