Suddenly a thin layer of residue appears on negs

[Elmarc]

Hello all,
As the title suggests, I have recently discovered a thin residue on the non emulsion side of some recent negatives.
My processing has not changed but something has...
Unfortunately, it is impossible to show this in a photo otherwise I would submit one.
The layer of residue is not evenly spread over the negative, it is interspersed with quite uniform vertical lines of clear sections that look like no effect has taken place in those areas.
I first noticed these artefacts on a blank frame. On closer inspection it is obvious that this residue has coated itself along the length of the 120 strip by looking at the spaces between the frames.
My initial thought is that this is photo flo. I was able to clean off the residue relatively easily with a soft cloth from the blank frame. I am a little hesitant to try to do the same over an image unless there is a possibility (presuming this is photo flo) that the negatives could be damaged by possible bacterial growth in the future.
I did examine a strip of 120 developed about a month prior which is perfectly clean.
I understand that this is almost impossible to pin down remotely and without a reference photo of the said problem but any advice on how to proceed (to clean or not to clean) would be greatly appreciated. Or if anyone has had a similar experience from photo flo going bad for example. For the record I use a 1:300 dilution mixed with distilled water.

Thank you in advance

Mar

 

[BrianShaw]

Have you tried re-washing the negative?

 

[Elmarc]

Have you tried re-washing the negative?

I did consider that, but how does one wash (and more importantly) dry 120 negs once cut?

 

[Don_ih]

A dilute solution of photoflo can get scummy if it sits around a while.

You rewash a cut 120 negative in a tray or load them all back onto a reel.

 

[Elmarc]

A dilute solution of photoflo can get scummy if it sits around a while.

You rewash a cut 120 negative in a tray or load them all back onto a reel.

The photoflo is always prepared from stock just prior to the final wash.

So one has to load each strip (in this case 3 frames) back onto the reel?

How does one hang them to dry?

 

[Don_ih]

How does one hang them to dry?

Clothes pins work well.

However, some people say that you need to make sure your photoflo is very well mixed into the water and then let it sit for a while before using, or you'll get residue. You may want to try mixing an amount the day before you intend to use it.

 

[koraks]

how does one wash (and more importantly) dry 120 negs once cut?

In a tray. Then hang up to dry from a corner using clothes pins or whatever other kind of pin/clamp/clip/whatever you find suitable. I use miniature paper binder clamps:

When rewashing film that has calcium/scale deposits on it (which might be the case here as well), I generally start with soaking/washing the film in a dilute acetic acid solution (e.g. 0.5%). Citric, sulfuric or sulfamic acid will work, too. Whatever you use, dilute it down because there's no reason to use anything particularly strong in this case.

After a few minutes in the acid bath, wash the negatives thorough in tap, filtered or demineralized water. If you have problems with fouling, I'd suggest a final wash (or two) in demineralized water with some photo flo added to it.

Too bad the phenomenon doesn't allow itself to be photographed (doesn't it, really, though?) because it sounds a bit puzzling. I'm very familiar with calcium/drying marks on 35mm film, but have never had any issues with 120 or sheet film because this generally has a gelatin coating on the backside which tends to prevent this sort of thing from happening.

 

[Elmarc]

Clothes pins work well.

However, some people say that you need to make sure your photoflo is very well mixed into the water and then let it sit for a while before using, or you'll get residue. You may want to try mixing an amount the day before you intend to use it.

I was just looking at the clothes peg option but there is not enough space for the peg to grip firmly once the negs are cut.
I have always used dedicated Kaiser clips which leave a deep imprint/impression on both tails. So they are not an option.

As for preparing the photoflo, I have always prepared just prior to the final wash with no problems in the past but I will try your suggestion. Thank you

 

[titrisol]

Refix and rewash
If scum is appearing after days or months and it looks "cloudy" is poor fixing

 

[Elmarc]

In a tray. Then hang up to dry from a corner using clothes pins or whatever other kind of pin/clamp/clip/whatever you find suitable. I use miniature paper binder clamps:
View attachment 360396

When rewashing film that has calcium/scale deposits on it (which might be the case here as well), I generally start with soaking/washing the film in a dilute acetic acid solution (e.g. 0.5%). Citric, sulfuric or sulfamic acid will work, too. Whatever you use, dilute it down because there's no reason to use anything particularly strong in this case.

After a few minutes in the acid bath, wash the negatives thorough in tap, filtered or demineralized water. If you have problems with fouling, I'd suggest a final wash (or two) in demineralized water with some photo flo added to it.

Too bad the phenomenon doesn't allow itself to be photographed (doesn't it, really, though?) because it sounds a bit puzzling. I'm very familiar with calcium/drying marks on 35mm film, but have never had any issues with 120 or sheet film because this generally has a gelatin coating on the backside which tends to prevent this sort of thing from happening.

I will try the paper binder clips hoping that there will be enough purchase.

Are you referring to stop bath?
If not, would stop bath be sufficient?

It did occur to me that this residue could be calcium. However, my processing regime includes pharmacy distilled water for developer and final wash. Fix and initial washes are prepared through a Paterson water filter with no problems until very recently

 

[Elmarc]

Refix and rewash
If scum is appearing after days or months and it looks "cloudy" is poor fixing

I am pretty confident that it is not a case of poor fixing. Fixer is always one shot and for the maximum specified time.

 

[koraks]

Are you referring to stop bath?

Stop bath will work. That's a dilute acid (citric or acetic) after all.

It did occur to me that this residue could be calcium. However, my processing regime includes pharmacy distilled water for developer and final wash. Fix and initial washes are prepared through a Paterson water filter with no problems until very recently

Well, that's odd. Something has changed for sure, because you now have a problem that you didn't use to have.

Maybe try refixing as well as @titrisol recommends. Milkiness due to inadequate fixing is immediately visible (but can be hard to judgde as long as the film is still wet) and should disappear rapidly when the film is treated with fresh fixer.
Sometimes on suspect pieces of film I'll place a single drop of fixer concentrate and just let it sit for 10 minutes or so, then wash the entire strip of film. If the place where the fixer was looks clearer than the surroundings, it's solid proof that insufficient fixing was the problem.

 

[Sirius Glass]

A dilute solution of photoflo can get scummy if it sits around a while.

You rewash a cut 120 negative in a tray or load them all back onto a reel.

Make sure that the negatives are propped up and not laying on the bottom or on top of each other.

 

[Elmarc]

Make sure that the negatives are propped up and not laying on the bottom or on top of each other.

Yes indeed. I was planning to wash the strips individually once I have settled on a method of hanging them. The is only 3mil maximum for a clip to grasp...
Otherwise I may look into cleaning with Pec Pads or a microfibre cloth. The residue is not too stubborn.

 

[MattKing]

Clip the rewashed and re-PhotoFlo'd strips very carefully on just one corner, and then hang them up. The short strips are very light, so a small clip will hold them.

 

[Elmarc]

Clip the rewashed and re-PhotoFlo'd strips very carefully on just one corner, and then hang them up. The short strips are very light, so a small clip will hold them.

Thank you Matt.
I will certainly try that first once I have found suitable clips

 

[250swb]

Are you talking about Kodak Photo-Flo specifically or an alternative, because not all are created equal?

 

[MattKing]

Little itty bitty clips - like these, or smaller:

 

[Elmarc]

Are you talking about Kodak Photo-Flo specifically or an alternative, because not all are created equal?

Yes, I am referring to Kodak Photo-Flo

 

[Elmarc]

Little itty bitty clips - like these, or smaller:
View attachment 360442

Perfect! Thank you.(and Koraks)
I will search back through recent negatives to find out how many rolls have been affected.
I'm beginning to question whether the photoflo had been mixed well enough in the distilled water.

 

[koraks]

Those clips are great, yeah.
I hope you can figure out the exact cause. Such problems are annoying, indeed!

 

[MattKing]

I'm beginning to question whether the photoflo had been mixed well enough in the distilled water.

FWIW, this is how I avoid PhotoFlo that isn't the right concentration when mixed: https://www.photrio.com/forum/resources/making-and-using-a-kodak-photo-flo-stock-solution.396/

 

[Elmarc]

Perfect! Thank you.
I will search back through recent negatives to find out how many rolls have been affected.
I'm beginning to question whether the photoflo had been mixed well enough in the distilled water.

Those clips are great, yeah.
I hope you can figure out the exact cause. Such problems are annoying, indeed!

Especially when a perfect workflow over hundreds of rolls suddenly changes!

 

[Elmarc]

FWIW, this is how I avoid PhotoFlo that isn't the right concentration when mixed: https://www.photrio.com/forum/resources/making-and-using-a-kodak-photo-flo-stock-solution.396/

Thank you Matt. Bookmarked.
I worked out an effective dilution for my tank many years ago by a little trial and error. I use a syringe to measure the concentrate then add that to the last two minutes of the distilled water wash. That has worked fine up until now.
I did initially keep an eye out for any residue or water stains until I was satisfied that the dilution was optimum.

 

[Doremus Scudder]

The photoflo is always prepared from stock just prior to the final wash.

So one has to load each strip (in this case 3 frames) back onto the reel?

How does one hang them to dry?

Just wash them in a tray, retreat with Photo Flo (mixed to the proper dilution since not-dilute-enough Photo Flo may be your problem) and hang from a line with a wooden clothespin from a corner (just like you would sheet film). It is easy to position the clothespin so it just barely grabs a couple of mm of the corner.

The suggestion to soak them in an acetic-acid solution (acetic-acid stop bath will work just great) is a good one.

If you aren't 100% sure your negatives are not underfixed, then refix before the wash too.

Another thought: Check your fixer for cloudiness. Rapid fixers can age and sulfur out due to oxidation. The first sign is a very slight cloudiness caused by very fine sulfur particles dropping out of solution. These can coat your film and stick quite stubbornly. Wiping may be the best way to remove the coating.

Best,

Doremus