Washing Out Optical Brighteners

[RalphLambrecht]

In another thread on APUG, a statement was made that extended washing of fiber-based papers can lead to a loss of optical brighteners in the paper. I conducted a test with Ilford MGIV-FB to find out how long it takes and if it has an effect on normal and overnight washing. Here are my results.

An unexposed 5x7-inch piece of Ilford MGIV-FB paper was processed normally (dev, stop and fix) and washed for 30 minutes. Then the piece was cut in half, one side dried and the other washed again, repeating the process until a washing sequence of 30 mn, 12h, 24h, 2 days and 4 days was achieved.

The paper samples were dried and mounted next to each other under glass. A UV source was used to test for remaining optical brightener in the paper. As you might know, optical brighteners work by absorbing invisible UV radiation and re-emitting the energy as light in the visible region of blue light.

The results are shown in the attached photograph. No loss of brightener was detected for 24 h of washing. After 2 days of washing a minor loss of brightener was measurable, and after 4 days of washing a very obvious blue stain appeared. I'm not quite sure of the reason but suspect a reaction between the slightly rusty paper weight and the paper. Now sign of any baryta break was seen in any of the samples.

My conclusion is that there is no harm to wash this fiber-based paper for extended times up to at least one day.

 

[Ian Grant]

What UV light source do you use to excite the optical brighteners ?

Where's the photos that's a diagram ?

You must have a high chlorine level in your water that prevents bacterial degradation, I'm glad I'm not drinking it

Ian

 

[Photo Engineer]

Ralph;

Many of these brighteners are heavily ballasted in order to anchor them in place. Early versions were just plain Stilbene derivatives with sulfonic acid groups to render them more soluble. This allowed many of the early ones to be washed out. I remember Agfa and Konica having a separate water soluble brightener, a yellow powder, which you bathed the print in. In RC papers they are actually dissolved in the resin helping them stay in place. Most of these are not very water soluble.

See here for a basic description: http://en.wikipedia.org/wiki/(E)-Stilbene

I am not surprised that the modern brighteners did not wash out. Another myth proven wrong by a real test.

Thanks.

PE

 

[RalphLambrecht]

It is a photo with text added in Photoshop. Not much chlorine at all but much better than drinking from your bacteria infected well.

 

[Ian Grant]

There's np images Ralph, also the file extension is .jpg.att which may be the issue.

It's worth looking for Simon Galley's recent post about how to wash the optical brightener out of Ilford Warm tone paper

Ian

 

[RalphLambrecht]

Trust me Ian, it's a photograph! I don't want to wash the brighteners out, and I'm glad not having to worry about it.

 

[lxdude]

There's np images Ralph, also the file extension is .jpg.att which may be the issue.

It's worth looking for Simon Galley's recent post about how to wash the optical brightener out of Ilford Warm tone paper

Ian

I'm having no problem seeing the image. Using plain ol' Firefox.

 

[ic-racer]

Thanks for testing this. I was going to ask you how you did the test. Good work!

 

[michaelbsc]

No image here, but my mobile drops the ball a lot.

 

[RalphLambrecht]

Here's a copy of the unmodified photograph. One can see how the brighteners make the paper glow when viewed under a 'black light'.

 

[Chuck_P]

No problem seeing the photo either, thanks for posting this Ralph. Very beneficial.

 

[Photo Engineer]

Ralph, would it be possible to include a non-brightened paper in the scene to accentuate or "highlight" (sorry for the pun) the differences between brightened and non-brightened papers? If you can get a powder form of an OB, you can imbibe it into 1/2 of a sheet and use that as a reference too. There are many ways to strengthen this image if it is unclear to anyone.

Another method would be to use a WR 2B or 2E filter over the light source and compare with and without UV illumination.

I think it is fine as is though, but if you want to go on, there is more that can be added to the imaging and the experiment itself.

Good Job!

PE

 

[frotog]

Thanks for posting this Ralph! I love it when people here do real world testing. But while it's always a good thing to know what the limits are I'm not sure how this test is beneficial. Why would you wash your prints for more than one hour? My concerns with overwashing (like more than one hour) have less to do with optical brightners and more to do with compromising the integrity of the paper fibers, having the emulsion seperate from the base and ending up with a print that dries to resemble a potato chip. Nonetheless...always love test results.

 

[Ken Nadvornick]

Why would you wash your prints for more than one hour?

By allowing them to soak overnight?

I sometimes finish darkroom sessions in the wee hours of the morning and don't want to stay up any longer waiting for a full one hour wash to complete. So I set the timer on the Intellifaucet for 60 minutes, then go to bed.

It's not really a desire for an extended overnight wash. It's just the reality of late night sessions.

Many thanks for this test, Ralph.

Ken

 

[Hexavalent]

It's worth looking for Simon Galley's recent post about how to wash the optical brightener out of Ilford Warm tone paper

Ian

I can't seem to find this post. Any ideas as to where it might be?

 

[RalphLambrecht]

Ralph, would it be possible to include a non-brightened paper in the scene to accentuate or "highlight" (sorry for the pun) the differences between brightened and non-brightened papers? If you can get a powder form of an OB, you can imbibe it into 1/2 of a sheet and use that as a reference too. There are many ways to strengthen this image if it is unclear to anyone.

Another method would be to use a WR 2B or 2E filter over the light source and compare with and without UV illumination.

I think it is fine as is though, but if you want to go on, there is more that can be added to the imaging and the experiment itself.

Good Job!

PE

PE

No problem, but I don't have such a photographic paper at present. However, I have old books without optical brighteners and, of course, the cotton mount shown in the photograph.

I could also cut the large sheet in half and turn one of them around?

In addition, I have four photographs from another test, which spent 10 years behind a south-facing window. The optical brighteners in these papers (also Ilford MGIV) are completely exhausted by now.

A powdered form of OB? Hmm... like that idea!

 

[RalphLambrecht]

By allowing them to soak overnight? ...

Actually, that was the original reason for the test. There are quite a few folks who do this, because after a long printing session, it's time to go to bed and no time left to do all the post processing steps until the next day.

 

[Photo Engineer]

Ralph;

I have a big bag of it here somewhere. There are many of them on the market. They are bright yellow crystalline materials that take on that eerie blue glow when illuminated by UV. The problem is that when a paper is made, often the brightener is also incorporated into the base side just for ease of manufactue. IDK in this case, I've never tested it and the brightener might only be in the baryta itself.

You will have to check this out.

PE

 

[RalphLambrecht]

Ralph;

I have a big bag of it here somewhere. There are many of them on the market. They are bright yellow crystalline materials that take on that eerie blue glow when illuminated by UV. The problem is that when a paper is made, often the brightener is also incorporated into the base side just for ease of manufactue. IDK in this case, I've never tested it and the brightener might only be in the baryta itself.

You will have to check this out.

PE

PE

Good point. I just checked again. There is no optical brightener (OB) in the base of MGIV-FB. I can easily implement your suggestion!

 

[RalphLambrecht]

Ralph;

I have a big bag of it here somewhere. There are many of them on the market. ...

Love to have some of it. For the test alone, would one of these whiter-than-white fabric detergents work?

 

[erikg]

Good to know. Long soaks are a good way to conserve water. I also like to leave prints overnight so I can finish next day. I've wondered about this, but on the other hand if you put prints behind UV glass isn't that negating any effect from the brighteners anyway? I have viewed museum prints under black light that showed a streaked pattern that would seem to match up to the water flow of a vertical print washer, but those would be prints at least 30 years old, so nice to know about modern papers.
Sprint Systems offers a liquid brightener, just FYI.

 

[Photo Engineer]

Love to have some of it. For the test alone, would one of these whiter-than-white fabric detergents work?

Fabric detergents work the same way and might work with papers. All brighteners turn images blue black depending on original tone. So, a warmtoned paper might turn neutral or cold and a cold toned paper might turn blue black.

PE

 

[Photo Engineer]

As an added note, long soaks of FB papers can decrease gloss and cause flaking at the edges of the baryta coating. Ferrotyping will fix the first problem and hardening will fix the second, but only to an extent. I suggest tests to determine the optimum soak.

And, with RC, this may cause delamination.

PE

 

[kozesluk]

a note from my own experience: Foma Fomabrom 111 after 12 h soaking in water changes the paper colour significantly (in comparison to ordinary 30 min washing).

 

[RalphLambrecht]

... I've wondered about this, but on the other hand if you put prints behind UV glass isn't that negating any effect from the brighteners anyway? ...

Not sure. I use ordinary 2mm float glass and with a black light the prints glow behind it like someone switched a light on. The only exception is one print that has been behind a south-facing window for 10 years (another experiment).