Strange marks on negatives - any ideas?!

[PaulW]

Can anyone possibly advise/help solve a problem I’ve been having with strange marks on negatives following development (in standard Patterson tanks of various sizes)? It always appears as shown on the scanned negative (120) attached - always down the same side of the negative, though very variable in degree between different films and different parts of the same film (this example is moderately bad), though with no pattern I can discern, always appearing as pale “blobs”. It’s like fogging, except it’s the opposite, being white on the negative, so perhaps an area of underdevelopment???


It happens with different film types and different developers, including Prescysol (I have generally used Ilfotec HC in the past, but one reason for wanting to try Prescysol was to see if this might get rid of the problem!). I’ve tried cleaning then buying new spirals in case there was any contamination. I’ve tried different patterns of agitation. I’ve tried adding a little wetting agent to the water for the predevelopment soak. Nothing seems to work! I’ve had the camera (Mamiya 645) & interchangeable film backs looked at, but it looks like a processing problem not an in-camera problem.


Any suggestions would be most welcome!


Many thanks in advance for any ideas!

 

[pdeeh]

There's nothing attached.

Scanned negatives are not a very useful means for diagnosis anyway

Much better to photograph the negatives with a digital camera on a light-table and post that.

If you don't have a light table, then a large smartphone, tablet or laptop screen can be pressed into service,or failing that you can tape the negative to a sheet of paper and hold it up to a diffuse light source for photographing.

the chances are you have airbells, and perhaps you need to check you are using enough developer to cover the film completely. I use 500ml for a Paterson tank for 120 and never have a problem.

Oh, and Welcome to APUG!

 

[gone]

I don't quite get the difference between a negative scan and a digital pic of a neg on a light table. That's essentially what a scan is.

 

[PaulW]

Thanks pdeeh. I have tried again to reattach the scanned negative below - the marks should be visible, but I can get a photograph too if needed.

I use 500mls per 120 film, so there should be enough volume, and I do a pre-soak with water at 20C & one drop of wetting solution (something suggested by Patterson when I asked them about this problem).

 

[Neal]

Dear PaulW,

I've never used Paterson tanks but it looks like you aren't getting full coverage of the film when developing. I would put the reel and core in the tank, fill the tank to cover the reel and measure how much volume is required.

Good luck,

Neal Wydra

 

[PaulW]

Thanks Neal. However this happens even when I'm processing 2 or 3 films - all films are affected, not just the one nearest the top!?

Cheers, Paul

 

[pdeeh]

I don't quite get the difference between a negative scan and a digital pic of a neg on a light table. That's essentially what a scan is.

well yes, loosely speaking that's true ... but the point is that people quite often post inverted scans of negatives, and inadvertently or unknowingly the contrast levels and so on get adjusted, which can make it hard to form an opinion on what might be going on, and very often don't include the rebate (which, when visible, can be very helpful in diagnosing of course).

Seeing the whole negative provides a much better context to make judgments.

 

[pdeeh]

Thanks Neal. However this happens even when I'm processing 2 or 3 films - all films are affected, not just the one nearest the top!?

Cheers, Paul

in which case, you might have to reconsider the possibility of a fault with your camera and not your processing.

You also need to exclude the possibility of a scanning artefact (another good reason not to rely on scans for diagnosing negative problems): can you see these "marks" on the negatives when examining them by eye or with a magnifier ?

(any old 50mm lens for 135 will do nicely for a magnifier if you don;t have a sherlock or a loupe)

 

[PaulW]

It's not a scanning artefact (I don't scan my negs usually - this was just done here for illustrative purposes) - the "blobs" are clearly visible to the naked eye, and on contact prints.

 

[ruby.monkey]

Air bubbles trapped by the reels? How are you agitating your film?

 

[RobC]

contaminated film spool. i.e. you haven't cleaned the paterson spools properly after using them last time.

I would initially have said spool had slipped up the column but on close inspection of neg after inverting and adjusting brightness/contrast I suspect its contamination but I can't be 100% sure about that.

It could also be air bubbles trapped as suggested above.

Do you rap the tank hard on work surface after inversions?

 

[mnemosyne]

We just had this a couple of days ago in a very similar thread, these are most likely areas of underdevelopment caused by air trapped between the film and the upper parts of the reel. Do you tap the bottom of your tank on a surface before you start your inversion cycles? This may or may not help to dislodge bubbles. Do you pour the developer in with the reel already inserted in the tank? If yes you might try it the other way round (put the reel in the filled tank). It may or may not help.

 

[PaulW]

Air bubbles do seem the most likely explanation (I think the edge affected is the uppermost), though I have not always had this problem. I've tried various agitation patterns, including simple inversion (continuously for the first 30s then 5s/2 inversions every 30s or 10s every 60s, tapping the base of the tank initially to try to dislodge bubbles), inversion with a twist/swirl (as Ansel Adams recommended I believe) & an initial 60s inversion period following by 10s every 3mins (one of the techniques recommended by Peter Hogan who produced Prescysol developer.

 

[PaulW]

Thanks again for all the ideas. To try to combat any contamination I've cleaned and also bought new Paterson spirals, to no avail! I do tap the base of the tank firmly several times after adding the pre-soak water and also after adding the developer and after the first period of agitation/inversion.

 

[RobC]

Why do you pre-soak? Try without a pre-soak which shouldn't be necessary.

And you rap the tank after every inversion sequence.

 

[PaulW]

The pre-soak brings the tank & film up to 20C (or whatever temperature you're processing at), removes the anti-halation layer (not that that's necessary) & wets the film so the developer can then cover it evenly. It should also make bubbles less likely! It's the way I've always done it (for 30 odd years!!) and I've always understood it to be standard, though probably not essential.

 

[RobC]

Film wasn't designed to require a pre-soak and infact Ilford don't recommend it as far as I'm aware.

But why has this started happening after 30 years? You must have changed something in your process/procedure which may point you to the cause.

 

[PaulW]

Pre-soaking is widely done, though I understand it's not essential - I can certainly try one without.

But the key question, as you say, is " ... why has this started happening after 30 years? You must have changed something in your process/procedure ... ", and unfortunately I haven't been able to identify what, hence my appeal for ideas/previous experiences.

 

[pdeeh]

All the more reason, along with the fact you've stated it happens even with several rolls in a tank at a time, to ensure that this isn't a camera problem that has only recently manifested.

 

[PaulW]

I had the camera & interchangeable backs checked & serviced recently, with no problems found (though that doesn't rule it out of course). My next step was going to be to expose two rolls of film identically (easy with the interchangeable backs on a Mamiya 645), process one myself as normal & send one to a commercial lab to see if they get the same problem!

 

[pdeeh]

It's the silver nitrate goblins then. You've done something to upset them

 

[R.Gould]

It looks to me as if the reel has slid very slightly up the center coloum, I always use a little more chemical than the tank needs in Patterson tanks, that is, I use 600ml for 120 rather than the suggested 500ml to guard against this happening after it happened to me a couple of times,

 

[MattKing]

What is your water like?

These look to me like a classic problem with air bubbles. Try to eliminate them by further experiments with your agitation regime.

Are you ensuring that there is at least some air space in your tanks, in order to make sure that the developer "tumbles" through the film when you agitate?

Can you determine whether the marks are always at the same edge (top or bottom) of the film?

And by the way, Simon Galley of Harman/Ilford has confirmed more than once here on APUG that by not "recommending" a pre-soak, Ilford is saying that it is not necessary, but as far as Ilford is concerned, it doesn't do any harm.

 

[railwayman3]

I had the camera & interchangeable backs checked & serviced recently, with no problems found (though that doesn't rule it out of course). My next step was going to be to expose two rolls of film identically (easy with the interchangeable backs on a Mamiya 645), process one myself as normal & send one to a commercial lab to see if they get the same problem!

I'm not familar with the Mamiya 645, so forgive me if I'm being dim, but the short edge with the marks is, I assume, the edge in the tank spiral ? In which case, it does look like something with the spirals ?

In any event, I do think that your idea of identical films with different processing will almost certainly solve where the problem is.

 

[Brook Hill]

Strange coincidence just looked at a film developed this week in Prescysol and it has the same marks. Can't be certain whether it is the edge at the top or bottom of the tank but thinking about the way I load the reels it is more likely to be at the bottom of the tank or at least sitting on the lower one of the two reels. I will keep a careful check on the next one.

Tony