Off Topic . Anyone Identify this Problem.

[alex coleman]

I know it's off topic.

Hoping someone here can help me out on this.

120 roll film Developed in Paterson Tank 500ml Of chemistery.

With home made spacer to keep the reel in the bottom of the tank.

Happening with different films and different developers.

It isn't fogging, because the negatives look fine until you look

closely and find this banding of different density along one edge

only, I assume it is the top of the film.

Sometimes Hardly even visible but noticeable when you print up the

image.

Could it be Developer Foaming, which I have noticed a bit, but then

I think all developers foam a bit.

It doesn't happen all of the time ?????

I have processed Hundred's of films but this leaves me slightly

puzzled.

[john_amiet2]

If it is indeed foaming, try using say 600ml of dev instead of 500ml, so that foaming occurs above the film. also, agitate gently rather than vigourously. If that eliminates problem, then you have found the cause.

[h._p.]

It does sound a bit like foaming. I use an old Paterson twin reel tank and I always put an empty reel in the top if I'm not using the full capacity, it's the only way I've found to guarantee that the reel won't lift above the level of the developer.

 

Incidentally, I use 500ml and invert three times every minute without problems though there's a fair amount of suds when I pour out the developer.

[btipton]

I've also had the problem, very frustrating!! One solution I've found is instead of just agitating for 10 seconds a minute from the start, I now do a slow steady agitation for the first minute then normal agitation 10 seconds a minute after that. Once I began doing this the problem has virtually gone away. It seems the first minute of development is very important, especially if a presoak isn't used, and constant developer movement won't allow the "bubbles" to form. I've never had the problem with 35mm.

Good Luck!

 

Bob

[lex_jenkins]

There are a number of risks inherent to developing 120/220 film, some of which are peculiar to plastic tank/reel systems. There have been several discussions about these problems this year on the B&W Film & Processing forum.

 

Here are some of these problems:

 

1. Foam is generated by agitation and can be trapped in the reel flanges. Bad enough that some developers are prone to foaming already (due to reduced surface tension - note the rather slimy feel of some developers), but any residue left over from a wetting agent such as Photo-Flo or LFN can be reactivated and add to the foaming problem.

 

The solution is to rinse the tank, lid and reels thoroughly after every session, particularly important when a wetting agent is used.

 

Rap the tank a few times against the work surface to dislodge bubbles. Using twist agitation with plastic tank systems, such as the Paterson and Spanish tanks, will help prevent reintroducing foaming. The flanges of plastic reels are more prone to trapping foam so it's best to avoid inversion agitation with these tanks.

 

2. The higher flanges of plastic reels interfere with chemistry flow to the film edges. While this generally goes unnoticed with 35mm film because of the wide borders around the sprocket holes the narrower borders of medium format film can be troublesome. Part of the exposed frame edges are actually covered by the higher, flat flanges of plastic reels. It's important to agitate assertively with plastic tank/reel systems.

 

The paradox is that inversion agitation, which is certainly assertive enough, can contribute to foaming. So I prefer aggressive twist agitation with the paddles provided for these tanks.

 

Also for the same reason plastic tanks/reels are unsuitable for stand development or prolonged intervals (longer than every minute). Not enough chemistry flow to the film edges.

 

This uneven development shows up as irregular edges along the length of the negatives. It can intrude as much as 1/2" from the film edges, tho' usually affects no more than 1/8"-1/4" along the edges.

 

3. Insufficient chemistry level. Two factors are at work here:

 

(a.) Plastic tanks have an irregular bump on the bottom designed to cam the reel spindle up and down with twist agitation. With inversion agitation the spindle may come to rest in the "up" position; ditto if twist agitation is used but care is not taken to ensure the spindle rests in the "down" position between agitations.

 

(b.) With inversion agitation chemistry can leak or be trapped in the rather complex light baffle/funnel of the lid. Up to 25ml can be trapped in the lid. Another 25-50ml can be lost due to leakage, depending on the tank. If only the bare minimum chemistry to cover the reel(s) is used there's a definite risk that the top of the uppermost reel can be left high and dry by the end of the development session, leading to uneven development along one edge.

 

Nothing wrong with plastic tanks/reels. I use both plastic and stainless. Both have their own quirks and need special handling precautions to ensure reliable results.

[mark_eban]

In the days when I developed my own 120 film in Patterson tanks I had this problem on HP5. Almost impossible to see until you printed it up. My technique was always to inserst the same end of the 120 film into the spiral first (forgive me but I cant remember which end). Someone pointed out that the two ends of the film are not congruent because one has the masking tape on it which attaches it to the film backing. This piece bends differently in the spiral and can create a differential flow in the developer. I thought this sounded utterly unlikely - however I tried reversing the end of the 120 film I put into the spiral first. The problem went away! It works in practice but I am sure it will never work in theory!

[jay_.]

Try a Kindermann tank and reel, with the rapid loader. I could never get the hang of hand-loading stainless reels and used plastic tanks for a while, but the Kindermanns load faster than plastic and you don't have the other issues. These days you can pick them up really cheap.

[roger_michel]

1. always use both reels in the tank whether or not you have two films. your "homemade spacer" may well be the problem. believe it or not, comapnies actually take some care in figuring how fluids will flow inside the tank. adding a foreign object may well cause problems.

 

2. many years ago, i picked up a cheap universal tank roller and have never used anything else since (for rollfilm). all the problems i ever had with inversion vanished. you can buy these for $10 at most camera fairs or on ebay. it will change your life. i use jobo tanks by the way.