Does anyone know what is causing this...

[MikemMG]

Hi, I am a new member - although I have been visiting for a few years now.
I have run into a problem and wondered if anyone might be able to advise me what is going on.
Please take a look at the attached image image :170217
as you can see there lots of spots visible and they appear to have a kind of highlighted halo around them.
Ive reviewed the negs carefully and by eye I cannot see the blemished - they are only apparent after scanning.
If anyone has come across this before and wouldn't mind sharing their knowledge I'd be much obliged.

Thanks

Mike

[chassis]

Debris is in the system somewhere. Need to have a clean workflow from the time the box of film is opened until the negative is scanned. If you are new to large format, this is a noticeable difference vs other formats.

Check for dust in the film holder, camera, negative drying area and scanner/scanner area.
Check for residue or particles in the wet processes such as developer, stop, fixer, wash, and equipment used to process the film.

It doesn't look like dry dust to me. It looks like maybe something in the chemistry or particulate that attached to the film when the emulsion was wet.

[Vaughn]

My guess it is the scanner if you can not see it on the negative. Good luck in tracking it down!

[gevalia]

Are you mixing developer from powders? If so maybe not fully dissolved.

[Michael Clark]

I was thinking air bubbles in the film development step.

[MikemMG]

Debris is in the system somewhere. Need to have a clean workflow from the time the box of film is opened until the negative is scanned. If you are new to large format, this is a noticeable difference vs other formats.

Check for dust in the film holder, camera, negative drying area and scanner/scanner area.
Check for residue or particles in the wet processes such as developer, stop, fixer, wash, and equipment used to process the film.

It doesn't look like dry dust to me. It looks like maybe something in the chemistry or particulate that attached to the film when the emulsion was wet.

Hi - Thanks for the consideration. I tend to agree that it might be something in the chemistry & I'm thinking that I need to get rid of the collapsible /concertinaed style chemical bottles as they seem impossible to clean out thoroughly. Perhaps brown glass bottles are the way to go? I've been drying the negs without too much thought for arriving particulates - I guess that has to be addressed also. I'll also have a good inspection of the camera and slides for dust.

Thanks again for the thoughts. I'll post again after I dev the next batch.

Cheers

Mike

[Rick A]

Looks like air bells to me. What method was used?

[chassis]

Mike, many of us have changed to PET plastic bottles for chemical storage. They offer the best oxygen barrier, second only to glass. PET bottles are easy and inexpensive to acquire; PET is the primary plastic used for beverage bottles such as soda, fruit juice, sports drinks and water. Brown plastic jugs, including accordion style, need to be a thing of the past for photochemical storage, because of poor oxygen barrier performance. Brown jugs use PE as the material, which is far less effective vs PET at preventing oxygen ingress. Plus as you mentioned the accordions are hard to clean. With PET bottles, simply dispose (recycle) when dirty or damaged, or wash them easily. Lastly, PET bottles have an effective perimeter lip seal integral with the cap. This is far superior to the face-compression type of seal found on many PE jugs.

[paulbarden]

I bet these are air bells.

[Pat Kearns]

Those are definitely air bells. You need to presoak.

[Barry Kirsten]

I've never seen air bells that look like this. My feeling is contamination from the accordion bottle resulting in particulate developer adhering to the gelatin. The developer 'grain' is locally extremely active reducing all the silver at that point. Bromine released locally restrains activity in the adjacent area resulting in the halo effect. A hypothesis only and I might be right off, but a good point for others more knowledgeable to debate.

[MikemMG]

I've never seen air bells that look like this. My feeling is contamination from the accordion bottle resulting in particulate developer adhering to the gelatin. The developer 'grain' is locally extremely active reducing all the silver at that point. Bromine released locally restrains activity in the adjacent area resulting in the halo effect. A hypothesis only and I might be right off, but a good point for others more knowledgeable to debate.

[John Layton]

Have you moved recently? I've seen iron contamination that looks somewhat like this. Otherwise I like Barry's hypothesis.

[Tobias Key]

I had some thing similar if I loaded my combi-plan with the film emulsion facing the centre of the tank. I put it down to developer splashing onto the emulsion as it filled giving more development to small areas. Do you develop in trays and keep undeveloped film near to the tray? Developer could splash out of the tray during agitation and land on the film if you agitated too vigourously.

[Barry Kirsten]

I think iron could also do it. When I tried recovering silver from used fixer, I put some ordinary kitchen foil aluminum into the old fixer and the silver precipitated out. This works because the more reactive substance (Al) reduces the less reactive (Ag). Iron being more reactive than silver could work in the same way. However iron in the water supply is usually present as an oxide (rust), so I don't know if it would work in the same way. I suppose it could... a dot of rust may still have more reactivity with respect to silver. Come on you chemists, we're scrambling around in the dark here.

[Doremus Scudder]

I concur with the last two posts; air bells (i.e., bubbles) on the film. The density difference is the giveaway: increased density where the surface of the bubble touches the film, decreased density in the middle.

Foaming developer can exacerbate this. So: make sure your tank has enough solution to cover the film completely and then some, rap the tank sharply on the countertop after agitating to dislodge bubbles and try to agitate with rotating, not shaking, motions to avoid foaming. If the problem persists, you may want to try pre-soaking your film for 3-4 minutes before pouring in the developer.

Best,

Doremus

[MikemMG]

Hi, thank you again for your considered comments. I'm off this morning and I'm going to try to purchase some glass chemical bottles and fresh chemicals in Manchester. I've not come across the expression 'air bells' before nor the potential of iron in the water potentially causing these issues. I haven't moved house recently so I'm assuming that 'air bells' or contaminates are the most likely cause - hence the quest for new glass bottles. As soon as I have developed a couple images I will post the outcome. Many thanks again for your input. Mike.

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[MikemMG]

Hi, amazingly hard to actually buy any 1 litre glass/PET bottles ! I have had to order some online. When they arrive I'll dev afew negs and feedback. Cheers. Mike

[Pere Casals]

Those are definitely air bells. You need to presoak.

Some film manufacturers do not recommend presoak bath, as it removes surfactants from emulsion that are included for development uniformity, see page 3: http://www.silverprint.co.uk/wp-content/uploads/2015/10/HP5-Plus.pdf


If using tap water it can contain air that it is released after it loses pressure, if the case it should be left for a while for degassing, it happened to me when diluting stock developer with tap water.

[MikemMG]

Hi, well the PET bottles have arrived and I have developed 4 negs. The result is ...no air bells/contaminates on the negs! This is fantastic. I'm thinking that the old chemical collapsible bottles were getting old and holding onto contaminates. I'm not ruling out the air bells as quite a few of you feel certain that that is what caused the blemishes. I'm just not sure how the arrival of new bottles might have influenced the lack of 'air bells'. Either way I'm very thankful for all your input and looking forward to getting back out with my MPP camera. Cheers . Mike

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