what's causing sprocket hole marks on developed negs?

[lynnb]

I'd appreciate advice about what I'm doing wrong here (scan has been high-contrast processed in LR to highlight the problem):

As you can see there's ghosts/light areas below the sprocket holes in the imaging area. This indicates to me there's something wrong with my agitation method.

This is 35mm AP400 (Tri-X) in D76, 10mins 1+1 dilution at 20C. Paterson two-reel tank inverted approx 6 times in first 30 seconds, thereafter inverted twice every minute. Empty reel or clip used to retain film at bottom of tank. I've used 500ml of developer rather than 290ml here, but the problem also occurs when I use 290ml so it has to be my technique.

After each inversion I rotate the tank 90 degrees. Following inversions, I smack the tank firmly on its base with my palm several times to dislodge any bubbles.

What am I doing wrong?

Thanks in advance for your suggestions,

 

[zuiko85]

Looks like uneven development. Perhaps the type of agitation used favors flow in only one direction. I would try a different type of agitation to see if that has any effect.

 

[Shac]

I'd agree it's an agitation problem - if I remember correctly (& I had this issue on many films) usually it's too vigorous and agitation. What method do you use Lynn?
I ended up following AA's suggestion of a slow taurus-like rotation (i.e. like a 3-D figure of 8 which included an inversion) which seemed to solve the problem I had.

 

[brusby]

Seems most likely to be the result of too little agitation with resultant local areas of developer exhaustion.

The lightest areas of unevenness on your print are near the top edge. On the negative that would correspond to the area just adjacent to the sprockets and the unexposed film edges. If I remember my film chemistry correctly, those unexposed areas use up developer at a pretty fast rate because all of that silver halide has to be completely developed and removed from the film base. That exhausts the developer much faster than mid tones or highlight areas found in the more central parts of the negative.

I'd guess the exhausted developer migrated down onto the adjacent exposed parts of the negative and left it's fingerprint as underdeveloped areas on the negative and lighter areas on the print.

i'd check to see if those light areas on the print are below the socket "posts" which were covered with emulsion but which were not exposed to light.

 

[Elektrojänis]

I had something like that when I first started to develop my own films. I used Tri-X in ID-11 so you are pretty much on the same path.

At my first tries on it I agitated by turning the tank upside down (four times every minute as advised on ilford documentation). This way I had sprocket hole marks like you. It was most visible on the frames I needed to boost contrast on and on some that were exposed a bit over.

I changed my agitation a bit after that. I still turn the tank upside down full 180 degrees but at the same time I use my wrist to rotate it around it's axis as much as my wrist allows. This practically eliminated the problem for me. I have still seen it on a few frames, but those were all pretty overexposed (or at least the edge was.

I use the same method with Microphen and Rodinal too exept with a bit different timing for rodinal (once every 30 seconds as per Agfa documentation). Some probably think it's too rough method for rodinal, but it works for me.

 

[lynnb]

thanks guys. Here's a scan including the sprocket holes. I'll change my agitation to ensure the developer swirls around more evenly and see what happens.

 

[Sparrow]

... bromide drag, I've only had it with stand developing in coffee, I use almost the same agitation times, cems and developer as you but I rotate rather than invert and never see it, if that helps

 

[Tijmendal]

Looks like bromide drag to me.
More inversions should solve the problem.

 

[brusby]

Yep, looks like exhausted developer (and bromide) migrating from the film edges onto the main part of the negative. Should be easy to fix with a better agitation scheme.

 

[jschrader]

If I remember my film chemistry correctly, those unexposed areas use up developer at a pretty fast rate because all of that silver halide has to be completely developed and removed from the film base. That exhausts the developer much faster than mid tones or highlight areas found in the more central parts of the negative.

I'd guess the exhausted developer migrated down onto the adjacent exposed parts of the negative and left it's fingerprint as underdeveloped areas on the negative and lighter areas on the print.

It does not seem plausible that the unexposed areas use up developer. The holes, like the "bridges" between them, do not contain exposed silver grains and should not react with developer (other than with fixer).

I would guess it is a hydrodynamic problem; the holes may cause the flow of developer, when the tank is tilted, to become turbulent and then, less fresh developer flows over the negative below the holes, thus the development is less effective.

Anyhow, the advice not only to tilt but the rotate along the long axis is probably good.

 

[brusby]

It does not seem plausible that the unexposed areas use up developer. The holes, like the "bridges" between them, do not contain exposed silver grains and should not react with developer (other than with fixer). . . .

I think you're right. It's been so many years since I considered film chemistry.

 

[mwoenv]

I had this when I first got back into developing, using a generic, no-name plastic 2-reel and tank set (I believe it was made in Spain, purchased from Photo Warehouse, Ultrafine). After I switched to Yankee plastic reels/tanks I never had this problem. Now I use stainless steel reels and tanks and never have this problem. Therefore, it seems that uneven developer flow around the outside of the first plastic reels caused the problem.

 

[chathaway]

slow but don't reduce your agitation...