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Thread: Does anyone know what is causing this...

  1. #11

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    Oct 2010
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    Brookfield, Vic., Aust.
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    415

    Re: Does anyone know what is causing this...

    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.

  2. #12

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    Sep 2017
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    6

    Re: Does anyone know what is causing this...

    Quote Originally Posted by Barry Kirsten View Post
    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.

  3. #13

    Join Date
    Mar 2005
    Location
    Newbury, Vermont
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    391

    Re: Does anyone know what is causing this...

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

  4. #14

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    Jul 2010
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    Chichester, UK
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    307

    Re: Does anyone know what is causing this...

    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.

  5. #15

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    Oct 2010
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    Re: Does anyone know what is causing this...

    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.

  6. #16

    Join Date
    Sep 1998
    Location
    Oregon and Austria
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    1,872

    Re: Does anyone know what is causing this...

    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

  7. #17

    Join Date
    Sep 2017
    Posts
    6

    Re: Does anyone know what is causing this...

    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.

    Sent from my Moto G (4) using Tapatalk

  8. #18

    Join Date
    Sep 2017
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    6

    Re: Does anyone know what is causing this...

    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

  9. #19

    Join Date
    Jul 2016
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    1,138

    Re: Does anyone know what is causing this...

    Quote Originally Posted by Pat Kearns View Post
    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-cont...0/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.

  10. #20

    Join Date
    Sep 2017
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    6

    Re: Does anyone know what is causing this...

    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

    Sent from my Moto G (4) using Tapatalk

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