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Edge under-developed spots on 120

polyglot

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Hi all,

see the spots on the right hand side here:

That's a 6x7 frame (long edge is the edge of the roll) of Acros souped in D-76 1+1 for 10:30. Two rolls of 120 end-to-end on a Paterson reel in a single-120 tank, 500mL of chems. Some frames have no problems, some are a little worse than this.

Agitation is 60s (inverting once per second, so 30 full cycles) at start then 10s (6 cycles of invert/uninvert) every 60s.

What am I doing wrong :confused:, other than trying to get BIF shots with a WLF at dusk?
 
I haven't had a problem with airbubbles, but this could be the cause.
I always "tap" the tank on a hard surface to dislodge any that may form - usually 2x at the start, then 1x after first minute.
So far no problems and I've been doing the same thing for over 20 years - so I guess it must be working!
 
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Air bubble is my first guess as well. When you rap the can, don't be too gentle. You gotta really wail to unspool the film. Be firm.
 
Yeah I rap the tank pretty hard and about 5 times after each inversion set. I guess it looks like bubbles that have floated to the top of the spiral - perhaps dislodged by the rapping but not gone through the spiral gaps. Would a couple drops of photoflo in the developer help?
 
polyglot said:
Would a couple drops of photoflo in the developer help?
Click to expand...

It may, D76 should have a sequestering agent to help in hard water areas but sometimes it's not enough.

If you add photoflo it must be the bare minimum because to much will cause foaming which can be worse still than air bubbles.

Rapping the tank hard doesn't remove the air bubbles fully if you have the Paterson twist-stick that comes with the tanks that can help. I have to add a couple of drops of Photoflo here in Turkey but the tap water is particularly bad.

Ian
 
Hi Ian,
Interesting comments regarding the Patterson twist stick version, as that's the one I use.
My method:

Pour in dev;
Rap 3x;
Agitate 60secs & rap 2-3x during initial agitation;
Sit 60 secs;
Agitate every 30 secs thereafter for remaining time.

Stop & fix as per usual;
Wash per Ilford/Kodak method;
Add Agepon/Photoflo for final rinse;
Hang to dry.

Negs print beautifully on Grade 2-21/2
And have yet to have an air bubble problem (now watch and see it happen with my next roll of film!!! )
 
I've recently had the same problem myself [with a roll of Rollei R3]. I assumed it was grease marks from my fingers from handling the film badly when loading. But air bubbles also make sense -- I'll watch out for it myself.

That's a rather lovely photo, btw.
 

*******
Airbubbles. That close to the edge of the reel makes one suspect residue on the coils helping keep them there.
 
500ml is just a bit over enough in a Nikor tank with a Nikor reel for 120 film. With the larger diameter Paterson tank, it sounds like it may not be quite enough. Put the reel in the tank, add enough water to cover by 1/4 inch, and measure how much water is in the tank.
 
500ml is fine for 120 in a Paterson tank per 120 reel, and the age/cleanliness of the reel isn't the root cause of the issue. The problem with air bubbles, is an old one, there have been numerous Patents for developer additives over the years to help prevent them.

See (there was a url link here which no longer exists) in this post, there was a good half inch of water above the reel which is almost new.

If your water is too hard then adding additional sequestering agent or wetting agent is the only option.

Ian
 
Might be totally off base/shot in the dark, but when I am making carbon tissue (gelatin, sugar and carbon), a splash of rubbing alcohol (91%) helps to get rid of air bubbles. If the alcohol does not interfer with the chemical processes, maybe it might help in film developing?

Vaughn
 
Alcohol's are used in a few B&W developer formulae, usually to help with solubility of a developing agent in concentrated devs but it should help.

Ian
 
thanks everyone (and mcgrattan!) - I'll try the one drop of photoflo and harder whacking. I have the twirly-style tank but no twirly-stick. That's a pretty damning photo, Ian.

500mL is enough dev: it's what the tank says to use and I always get development all the way to the edges. I generally don't get this bubble problem at all (seen it twice now out of ~50 rolls), but we do have a lot of iron in our water (Perth, where the fences and posts under roadsigns are red-brown from being watered) and it's possible that the level changed recently. For reference, I generally use 1mL of photoflo in 500mL for final rinse; it foams up a lot but I still don't get proper sheeting action off the film and have to squeegee if I want to avoid drying marks.
 
If you have some Edwal LFN yes, any other brand no. You may only need to top your tank off a little fuller, as this may be a bit of foam clinging to the top edge of your reel.
Rick
 
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