Dark patches along bottom edge of 120 negatives

[david_parmet1]

This problem cropped up only a week ago and it only happens

when I develop two 120 rolls in a large stainless steel tank. I've

done this before dozens of time with no problem but only last

week I noticed on the bottom roll dark patches running parallel

to the bottom edge of the roll relative to how it rests in the tank.

 

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The patch seems darker on the part of the negative that sits on

the outer part of the reel and less apparent on the part that's

further in the middle of the reel.

 

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Just for the record, when developing two rolls of 120 I mix the

delveper and pour it into the empty tank - turn off the lights and

roll the film onto the reels -- slowly lower the reels into the tank --

turn on the timer and start aggitating. When the developer is

finished I turn off the lights again -- pour out the developer and

hold the tank under running water for two minutes allowing for

five complete water changes before pouring in the fixer and

turning the lights back on.

 

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Any ideas on what's causing these patches? Could it be

because I'm not using an acid stop bath?

[ted_kaufman]

I'm afraid I don't have an answer for what might be causing the

marks. I can say, however, I see nothing wrong with your technique,

and I do not feel the problem is due to using a water bath in lieu of

an acid stop. I use the same procedure, and have for a mountain of

film, and haven't seen this problem. So I don't think an acid stop

will fix it.

 

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Have you changed anything in your procedure of late? What developer

do you use. What fixer? Is it possible your fixer is nearing

exhaustion? Why not try all new chemistry with immaculately clean

tanks and reels and see if that does not eliminate the problem.

[michael_feldman1]

Is it possible that the roll was exposed to light, possibly because

the paper was not wound tight? Can you put a picture of the

negatives on a web site?

[david_parmet1]

Ted - I use Ilford Rapid Fixer mixed 1:4 and I don't reuse it. I

normally fix for 4 minutes followed by two minutes under running

water, a minute in PermaWash and another two minutes rinse

followed by a minute in LPN. I use Hewes stainless steel reels

and I rinse them after every use.

 

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Micheal - I thought so at first but it doesn't look like light leaks

and this is the second time it's happened.

 

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Like I said, I've never seen this before.

[ted_kaufman]

I'm stumped, David. Everything sounds fine to me. I'll be interested

in hearing what it is when you finally resolve it, though.

[georg_kern]

Dont't think too complicated (I'm waiting for someone who will

explain it with the "Xtol-failure"). That's definitely just stray

light on the film edges. It may happen while loading or unloading the

film or while preparing it for development. It can occur

occasionally, because just a few seconds more or less in the light

can make all the difference. Additionally, high-speed film is more

susceptible than slow films (surprise). Some types of film seem to be

wound looser than others (from factory on). Heat, vibration etc. also

may loosen the film.

Other (unlikely) explanations: the magazine leaks light (but in this

case the darkening would affect a greater area) or the fixer didn't

reach the film at areas, where it is in contact with the reels (but

this would cause shiny patches, not dark).

[scott_walton1]

I think it sounds like a light leak. If your roll was would tightly

then check your felt traps in your camera back. You can find

replacements for this at this address:http://www.micro-tools.com/

Merchant2/merchant.mv?Screen=SFNT&Store_Code=MT

Cheers

[mike3]

I will find a similar problem if not careful loading 120 in the sun

and also if I do not roll the finished roll very tight. The first

case affects the beginning of the roll and the later affects the end.

[nigel_smith2]

Just to expand on the discussion a little...<P>

Sealing 120 roll films has always worried me. The glue that sticks

the paper down/around seems to be pretty good, but if it ever lets go

your film will be stuffed. Always possible when trying to change

rolls in a hurry! What I do is I keep a supply of small rubber bands

in my bag and add one for insurance. Also, if you away from home for

days/weeks, having something nice and solid to keep exposed rolls in

is a good idea. I've seen some very nice machined aluminium

canisters for 120 roll film but they were quite expensive. I have

some M&M (sweets) containers that hold a roll but they are not light

proof (might be water proof though.. the lids snaps shut pretty well,

must test that!), just a bit of protection from bumps.

[david_parmet1]

I think I've solved my problem. The dark marks were from

over-agitation. Basically with two 120 reels in there there is still

enough room for them to move around when I aggitate leading

the bottom reel to get too much aggitation.

 

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I ran a test with two reels and a 35mm reel in there to hold them

tight. I filled the tank up to the top and developed normally. No

staining.

 

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You learn something new every day....

[mark12]

That used to happen to me until I stopped agitating in figure eight

motions.(Yeah I know.) I now agitate with vertical motions and this

seems to provide even development throughout the negs.

Mark