Spots on unexposed film areas

Hello Photo community,

 

I am experimenting with rather rare but interesting AGFA Copex Rapid film and getting some odd spots on negatives as seen on the attached picture. They results into barely visible light spots on the print. What is interesting is that these spots only show up in unexposed or weakly exposed areas of the entire negative. Well exposed areas are totally free of any spots.

 

I develop the film with distilled water, temperature and timing are correct. Chemicals used are newest Dokuspeed kit (special developer for this film), ILFOSTOP stop bath and Ilford Rapid fixer. Wetting agent is ILFOTOL. Entire process done with distilled water, except rinsing.

 

I don't get this effect with any other film. My "theory" is that some micro particles (dust? tap water used in rinsing or residuals in the tank?) are better glued to specific areas of the film whereas they don't glue to well exposed areas. Did anyone experienced similar effect? What could go wrong?

 

Thanks,

Alex

 

How old are the chemicals and did you mix them thoroughly before using them ?

Developer parts (SPUR Dokuspeed) and stop bath are brand new. Fixer is ca. 4 months old. Mixing was not really thorough, but since I get consistently good results with any other film I thought it's OK. I recently ordered a new bottle of fixer, so will be able to try it out. The film is brilliant, so I really would like to get the process right :)

How to you rinse and dry the film? Do you use a wetting agent such as photo flo, or a drying aid such as isopropyl alcohol, or simply tap water?

When you mix the chemicals, it's a good idea to stir them more than you think you should. If they are powder chemicals, stir long after the crystals look dissolved.

 

If the chemicals are liquid, same again, keep stirring long after when you think the liquid and water are mixed.

 

Old mixed wetting agent can cause that sort of problem as well, if it's not filtered

Rinsing was 5 changes of water with 5-10-20 overturns on each change (product sheet shipped with developer mentions that rinsing can be reduced to 5 min, so it doesn't sound like this film is very sensitive to rinsing). Wetting agent was ILFOTOL (added on last change).

 

Product sheet also mentions that it doesn't recommend to apply wetting agent in the tank used for development because residuals of wetting agent in the tank may lead to development errors later. I don't follow this recommendation because I've never seen any degradation of development quality with any other film.

 

Also, it recommends drying the film with a gentle pass by soft side of kitchen paper which I do. Indeed it seems to work very well. Dried film is perfectly clean, without any signs of water stripes, dust particles or anything like that.

 

Current options I see to further track this problem down:

- Try with all brand new chemicals, mix them very thoroughly

- Do entire process in distilled water

- Rinse 5 min or more under running tap water as mentioned in the manual

- Try not using ILFOTOL wetting agent

When you mix the chemicals, it's a good idea to stir them more than you think you should. If they are powder chemicals, stir long after the crystals look dissolved.

 

If the chemicals are liquid, same again, keep stirring long after when you think the liquid and water are mixed.

 

Old mixed wetting agent can cause that sort of problem as well, if it's not filtered

 

Thanks for the suggestion, I will try next time. Indeed this developer is a mix of 2 parts, and perhaps not mixing them really properly triggers such development error. I'll try to improve. Wetting agent is a couple of months old and it's not been mixed. Never had a problem with it...

My work with Copex has always produced cleared margins after fixing. I do not see that in your example. Copex only needs several minutes in good fixer to produce a negative just like other film. The image is what is super about Copex. Use the leader tongue to test if the fixing is 1-3 minute max. Bill

First, every film photographer should carry a 10X loop. I have Bausch and Lomb 10x loupe. Anyway, examine your negatives using a magnifier. Look at the spots by transmitted light (holding them ups to a lamp) and by reflected light (lay them on a black surface). Next, look at the spots from the side. Are they elevations or craters? I will bet they have some elevation!

 

The film emulsion consists of a gelatin binder in which the light-sensitive goodies are held in suspension. Gelatin is used because it is transparent, flexible, has low solubility, and swells when wet. The swelling allows the fluids of the process to percolate inside so it can reach the light sensitive goodies. When the process is complete the film is allowed to dry. As the emulsion dries, the gelatin shrinks back to almost its original thickness. Note the word “almost”. This is the key to understanding water-marks. During the drying stage it is important that we squeegee or otherwise cause residual water on the film’s surface to be uniform. If droplets are present, the drying rate will be a variable. Areas under the water droplets dry more slowly than areas that are just damp.

 

Water drops set the stage for a lack of uniformity when it comes to drying. Worst, the surface droplets retard the shrink speed. What happens is the emulsion under the droplet has more elevation than their surrounds. Different thickness and different contours induce changes in the index of refraction. The result is what we call water spots, and these are difficult, if not impossible, to eradicate.

 

Additionally, most all water contains dissolved minerals and gasses. As the water evaporates, the mineral content remains behind. Thus the water spot is a mix of a change in elevation and mineral residue.

 

The best cure is prevention. We squeegee or use a wetting agent or both to cause the water on the film to sheet, not bead up. Old time darkroom workers kept glassless negative carriers in their arsenal of enlarger accessories. These reduced spots on prints by not providing glass surfaces that accumulate dust. Additionally, negatives could be printed while wet. This allowed speedy printing, plus printing wet negatives is a valid method to salvage frames that have water-marks. You see, re-wetting film allows the gelatin to swell, and this action will temporally quash water-marks.

Thanks a lot for your suggestions! Very interesting.

 

What puzzled me in this case is that I never ever had anything even close to this with any other film (standard films - Ilford, Kodak, AGFA...), so I thought my overall process and drying in particular are not that bad. ILFOTOL wetting agent always worked perfectly. It could be that AGFA Copex Rapid is less forgiving to the process flaws indeed. Anyway, I will definitely pay attention to all tips mentioned here and see if I get it right.

"Also, it recommends drying the film with a gentle pass by soft side of kitchen paper which I do." That might not be such a good idea.

 

A good washing in gently running water under the tap for 10-15 minutes (not just a few water exchanges), followed by Kodak Photo-Flo (or other brand) wetting agent and then hanging the film to air dry in a dust free area (a film drying cabinet, or a bathroom where hot water has created some steam to reduce the dust in the air) is best. If you're in a hurry, a soft, rubber film squeegee can be used, but make certain the edges of the squeegee are completely clean and undamaged. I wouldn't touch the wet emulsion with anything else, certainly not kitchen paper.

I've always heard that a squeegee is a no no, since they can frequently cause scratched negatives. As a result, I've always used Photo Flo. I NEVER had scratched negatives as a result.

"Also, it recommends drying the film with a gentle pass by soft side of kitchen paper which I do." That might not be such a good idea.

 

A good washing in gently running water under the tap for 10-15 minutes (not just a few water exchanges), followed by Kodak Photo-Flo (or other brand) wetting agent and then hanging the film to air dry in a dust free area (a film drying cabinet, or a bathroom where hot water has created some steam to reduce the dust in the air) is best. If you're in a hurry, a soft, rubber film squeegee can be used, but make certain the edges of the squeegee are completely clean and undamaged. I wouldn't touch the wet emulsion with anything else, certainly not kitchen paper.

 

I agree it sounds strange, but that's what official SPUR Dokuspeed developer data sheet recommends. I tried it - and it seems to work well. There are no scratches, no particles, no stripes or anything like that.

 

Here is the link (unfortunately I couldn't find English version), in particular item 3 about rinsing and drying:

https://www.fotoimpex.de/shop/images/products/media/41125_4_PDF-Datenblatt.pdf

 

Could it be that film chemistry experts recommend a method that could potentially ruin a film?

 

Today I developed a roll of APX 100 with exactly the same chemicals (except for developer) and exactly the same rinsing and drying method, in the same tank. Negatives came out just fine. No spots or damages of any kind.

 

I ordered another couple of Copex Rapid rolls to see if process improvements like better chemical mixing, more intensive rinsing etc. will help to solve the problem. Also ordered a magnifier to eventually examine the spots closely. If nothing helps, I have Plan-B ready which is development in Caffenol :D

I've never used that film, so I can't comment on the manufacturer's processing instructions, but all wet film emulsions can be easily damaged by any sort of handling. I agree with Vincent, even a clean squeegee can scratch the emulsion, so it's always best not to use one; proper washing, use of a wetting agent and air drying in a clean, dust-free environment is best. If you suspect powdered developer particulates are causing the problem, a liquid developer and fixer could solve that. And if all else fails, you might want to sacrifice an unexposed/undeveloped roll of film, and inspect it carefully with a loupe to rule out any manufacturing defects in the emulsion.

Looks like what you get when trying to fix film with fixer that has died and sulfured out. The white specks look like the sulfur particles I got when I last made this exact mistake. The Copex film base should be as clear as glass after proper fixing. Check the Ilford Rapid Fixer concentrate. If it smells bad and has a precipitate then it has gone off.

I doubt that it is any kind of surface contamination given that it only affects the shadow areas of the neg.

Looks like what you get when trying to fix film with fixer that has died and sulfured out. The white specks look like the sulfur particles I got when I last made this exact mistake. The Copex film base should be as clear as glass after proper fixing. Check the Ilford Rapid Fixer concentrate. If it smells bad and has a precipitate then it has gone off.

 

Thanks! Fixer is indeed fairly old (4 month since bottle opening). Also, prescription for fixing this film is only up to 60 sec which is quite short, so indeed it could be more sensitive to fixer delution quality than most of other films. I’ll use fresh fixer next time.

These look like drying marks from hard water. Make sure that you are using a drying agent, like Photo-Flo, and hang your film to dry. Never dry on the reels.

 

I have ALWAYS used a squeegee and never had a problem. Keep it clean and rinse it well each time you use it. I rinse mine in Photo-Flo before running it down a roll of film.

How much are the spots restricted to the largely unexposed parts of the neg? If they really are, then any form of dust or other particulate contamination seems unlikely. I had something similar recently, although my spots were IN the emulsion, and I think I have narrowed it down to the fixer ( not 100% sure yet) See here: Emulsion defect?

How much are the spots restricted to the largely unexposed parts of the neg? If they really are, then any form of dust or other particulate contamination seems unlikely. I had something similar recently, although my spots were IN the emulsion, and I think I have narrowed it down to the fixer ( not 100% sure yet) See here: Emulsion defect?

 

It is almost 100% restricted to shadow or unexposed areas. Thanks for the ref to your thread. In my case spots have circular form, on prints it appears almost as kind of glare bokeh. I never had any problems with FP4 by using DD-X + ILFOSTOP + Rapid Fixer + ILFOTOL + tap water which is quite hard in place where I live. I got an impression it is sturdy, forgiving film. Copex Rapid is actually first film I ever have problem with.

 

I am about to get a couple of more rolls + fresh bottle of Rapid Fixer, and also will try with Tetenal superfix. I will also perfect chemicals mixing and the timing, use distilled water for rinsing and will not squeegee or otherwise touch the film for drying. Let's see if that changes anything.

I haven't had a problem in the film from Ilford Rapid Fixer, but I have had it silver plate the inside of bottles.

 

There is a pH change with time, unless you measure and correct it, which causes problems.

 

You might try refixing with new fixer. It pretty much can't hurt, and might help.

 

I am hoping to find a pH meter, so I can test the fixer often enough. It isn't all that expensive, though.

 

I suppose it could also go bad in a partially used stock bottle, but I haven't found that a problem.