Washing Out Optical Brighteners

[Ian Grant]

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

Not sure where to find it, it was a thread about MG Warmtone and the change in it's base colour, however the data is in Ilford's own “Ilford Multigrade Papers, A Manual for the Darkroom.”

All Multigrade papers, except Multigrade FB Warmtone, have anchored optical brighteners which means they won’t wash out and the paper stays white. With Multigrade FB Warmtone, the brighteners can be removed with extended washing for an even warmer base tint.


So Ralph's test here correspond to Ilford's own data. It's well over 20 years since I switched to Warm tone FB papers, and the early Multigrade FB I used prior to that behaved differently.


Dave Butcher, a former Ilford employee, was their specialist on B&W papers and (there was a url link here which no longer exists) Post #14 and post #

I've added this link because of his comments about paper softening with an overnight wash, and also Foma & EFKE may not use anchored optical brighteners, and their emulsions are already much softer to start with.

Ian

 

[RalphLambrecht]

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).

Lukas

Thanks for reminding us: Drawing conclusions from the results of one paper for another is always risky. One needs to test one's own materials and methods to be sure. Even the dev, stop and fixer may have an influence, because different pH levels in the processing chemicals may make a difference.

 

[ic-racer]

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?

Don't know about the rest of you but I can't see UV, so it makes no difference for me.

 

[RalphLambrecht]

That's good to know, thanks Ian.

 

[michaelbsc]

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?

Don't know about the rest of you but I can't see UV, so it makes no difference for me.

The idea behind the Brighteners is that they fluorescence the UV converting it to visible light.

My guess is that display behind UV glass would negate the presence of the brighteners in the paper, but I personally don't frame with UV glass. I have no clue how transmissive ordinary glass is to UV, but clearly there is enough that UV filters have a market.

 

[frotog]

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).

Yes...I too have noticed color change with longer washes. In particular, Forte polywarmtone goes to a true brown after being in the wash for a day or so.

 

[Photo Engineer]

Some papers include dyes or pigments in the baryta to impart warmer or colder appearing tones to the image. Also, some contaminants can quench OBs, so longer washes can wash out the tints in the baryta or prevent the OB from fluorescing under UV. This can depend on the pigment or OB or process, and can even extend to the type of water used for washing.

PE

 

[Gerald C Koch]

I don't know at what wavelength the optical brighteners work but glass absorbs alll but the very near UV. The tests would be better done without any intervening glass.

 

[RalphLambrecht]

I don't know at what wavelength the optical brighteners work but glass absorbs alll but the very near UV. The tests would be better done without any intervening glass.

According to wikepedia:

Optical brighteners are dyes that absorb light in the ultraviolet and violet region (usually 340-370 nm) of the electromagnetic spectrum, and re-emit light in the blue region (typically 420-470 nm).

The light source I used peaks at 365 nm.

 

[Nicholas Lindan]

Interesting experiment. I was always leery of the brighteners leaching out. I use the serial soak method of print washing and have fluorescent lighting where I have the washing tray. After the prints have soaked for 10 minutes there is a distinct purple glow/tinge to the water from brighteners. I imagine the amount leaching out is very small compared to the amount remaining in the paper.

After 24 hours, though, it isn't the whiteners leaving the paper that I worry about but the emulsion leaving the paper.

 

[Martin Aislabie]

In the late 70s/early80s, I had experience to discover that FB Prints left to wash for more than 24hrs, would cause the emulsion to lift off the paper base.

Has this problem been overcome?

Martin

 

[Ian Grant]

No, I had it happen in the 80's/90's and to scraps test strips etc more recently 24 hr's is long enough for damage to occur.

Ian

 

[RalphLambrecht]

In the late 70s/early80s, I had experience to discover that FB Prints left to wash for more than 24hrs, would cause the emulsion to lift off the paper base.

Has this problem been overcome?

Martin

It must depend on the paper. I tested Ilford MGIV-FB and the emulsion showed no damage after four days in 20C water. There was a bit of fringing at the edges after two days, but that went away after drying.

 

[Mark Crabtree]

No, I had it happen in the 80's/90's and to scraps test strips etc more recently 24 hr's is long enough for damage to occur.

Ian

Water temperature is probably a major factor also.

 

[Ian Grant]

It must depend on the paper. I tested Ilford MGIV-FB and the emulsion showed no damage after four days in 20C water. There was a bit of fringing at the edges after two days, but that went away after drying.

The water will be just as crucial, also whether it's running or still. It's a combination of factors and once bacteria get a hold the emulsion breaks down very quickly.

24 hours is usually the limit using mains tap water before the emulsion begins to soften & disintegrate. I think you were rather lucky there Ralph as it's not the norm.

Ian

 

[Martin Aislabie]

The water will be just as crucial, also whether it's running or still. It's a combination of factors and once bacteria get a hold the emulsion breaks down very quickly.

24 hours is usually the limit using mains tap water before the emulsion begins to soften & disintegrate. I think you were rather lucky there Ralph as it's not the norm.

Ian

It made such as mess of the wash tank I have never been tempted to repeat the exercise

I don't remember which Kodak paper we were using but I do remember the sore arm and shoulder muscles needed to scrub the emulsion off the side of the tank

Martin

 

[Tom Kershaw]

Although some of the lower tech papers may be worse I've found that even modern products such as MCC or MGWT can become surprising soft or degraded over the course of too long a soak, meaning that I now tend to run the washer even if not full, when still predicting to print later in the day.

Tom

 

[RalphLambrecht]

The water will be just as crucial, also whether it's running or still. It's a combination of factors and once bacteria get a hold the emulsion breaks down very quickly.

24 hours is usually the limit using mains tap water before the emulsion begins to soften & disintegrate. I think you were rather lucky there Ralph as it's not the norm.

Ian

Ian

I don't see how bacteria can make such a mess as you are claiming within 24h. Our tap water is cleaner than that. Nevertheless, the test was meant to simulate someone needing to leave otherwise processed prints in standing water for later post processing, not washing for days. There is no need to do so.

 

[bill spears]

Regarding leaving prints overnight in a water bath (in order to finish washing the next day) .......
If there is fixer still leaching out of the paper, then the print will be 'stewing' in fixer contaminated water for some time ?? Or is it neutralised/diluted enough not to do any harm ??

 

[Ian Grant]

Ralph, bacteria can turn cold Chicken into a very hazardous meal within 3 hours if not refrigerated.

Gelatin is a culture medium for bacteria in laboratories, all tap water contains bacteria although below a permitted level. Leave that water still for even a few hours and the bacteria level is high. 24 hours and it's enough to begin attacking the gelatin in a film or paper.

You may be lucky/unlucky depending on our perceptions to have tap water with a high chemical/anti-bacterial content. typically chlorine, that's suppressing the bacteria, but it's not the norm in most countries.

Ian

 

[Photo Engineer]

Ralph;

I would pose this question from another angle. Although the US uses Chlorinated water, many counties use Ozone to treat water. It would be interesting to know the effect of Ozone vs Chlorine on papers, images and brighteners. These are a few among a lot of other questions that might be asked.

Just as an example OTOMH, I can think of situations regarding some organics where Ozone will oxidize something, but Chlorine will react directly with it and add a chlorine atom to it. You get different results with different rates. Brighteners are present at rather low levels and if there is enough Chlorine or Ozone present, and if the pH is right, strange things might take place.

PE

 

[RalphLambrecht]

Ralph, bacteria can turn cold Chicken into a very hazardous meal within 3 hours if not refrigerated.

Gelatin is a culture medium for bacteria in laboratories, all tap water contains bacteria although below a permitted level. Leave that water still for even a few hours and the bacteria level is high. 24 hours and it's enough to begin attacking the gelatin in a film or paper.

You may be lucky/unlucky depending on our perceptions to have tap water with a high chemical/anti-bacterial content. typically chlorine, that's suppressing the bacteria, but it's not the norm in most countries.

Ian

I don't think luck has anything to do with it. When I'm in Detroit, the chlorine level in the tap water is so high, I can smell it. In the UK and in Germany, I can not. May, they use ozone like PE mentioned. The test was done in Germany, and I will have it repeated in the UK.

Of course, I cannot speak for most countries (who can?), but I think you are exaggerating the bacteria problem a bit. Maybe this is totally different in Turkey, I don't know. I'm sure water temperature has a lot to do with it too. Remember, I had the paper in water for 4 days! I could feel some slime on the inside walls of the bucket after that time, but the paper was fine

Let's be realistic. I just wanted to know if one can leave a print in the water overnight, or up to a day, for later processing. From what I can tell, it won't be an issue. If it is, in some cases, as dramatic as you make it out to be. I'm sure people will notice and adopt a alternative technique fitting their circumstances.

Maybe somene else can also stick a piece of FB paper into tap water for a day and see if this destroy the baryta layer! However, stick to the paper, no cold chicken please.

 

[RalphLambrecht]

I just found something on this subject in David Vestal's 1984 book, called 'The Art of B&W Enlarging', and I quote:

There is some fear that long washing may remove much of the brightener from fiber-based paper, as it does from RC papers.
I tested this with a brightened Kodak fiber-based paper, Polyfiber, by comparing the white margins of prints washed 30 minutes with other prints that had been washed for 21 hours.
I saw and measured no difference, but sent white samples to Dr. Richard J. Henry and to Henry Wilhelm for critical comparison. Dr. Henry found a 10% loss of fluorescence in the long-washed paper, and both consultants found a 2% loss of white-light reflectance. This density increase of log 0.01 is just on the edge of visibility. It did not worry me: it reassured me.

He did not mention anything about the condition of the paper after the test.

My test was done with a different paper and different water, but it came to the same conclusion.

 

[Louis Nargi]

Thanks for this thread. I'm one them.

 

[Ian Grant]

Ralph, UK water is often treated with Ozone as well as Chlorine, that's common in most of Europe because Chlorine doesn't kill Cryptosporidium. (I've no darkroom in Turkey).

The bacteria problem is very real and certainly not an exaggeration. David Vestal's test was 21 hours, which is about the limit, water quality and bacterial load will vary substantially but past 24 hours and the gelatin will normally be gin to be attacked.

It's interesting that David Vestal test didn't go past 24 hours, but then perhaps he did

Ian