Peter Hogan
4th February 2009, 09:05 AM
I was intrigued by the discussions about the edge markings on a recently posted 120 image, and particularly the possible causes. I have occasionly suffered with the same problem, and this was not the first time it had been mentioned on here, so I have spent the best part of two days testing.
Foaming and contamination had been suggested. I discounted contamination my other chemicals - just not viable, and concentrated on foaming.
I thoroughly cleaned two dev tanks in the dishwasher, then developed a roll of 120 in each tank, using partial stand agitation. Fixed and washed. In one tank I used a washaid (Kodak) and in the other alcohol and dist. water. Both films were perfect.
I then washed out both tanks by a general 'swill' with clean cold water and left them to dry.
I developed two more rolls of film, noting which tank had had the washaid in, using the partial stand method. I should point out that the agitation I use is 'gentle' - pouring the dev gently down the side of the tank during inversions and a gentle 'swirl' for lateral movement. Both films fixed and washed and washaid added to the same tank as previously. Both films perfect.
I repeated the experiment as before, developing two more films, but I was far more energetic, giving some shaking to the tanks, and inverting rather vigorously. Partial stand. Films fixed and washed, washaid in the same tank.
Eureka! The film from the washaid tank had those markings! The other film, perfect. I repeated this experiment another two times, once with gentle agitation, once with vigorous agitation and the results were the same; vigorous agitation in a tank previously having washaid in produced the marking, obviously from foaming. (which you could in fact, see, as it bubbled up through the pouring hole.) Films from a washaid-free tank always perfect.
Conclusions;
a)Washaid used in a tank can produce foaming in subsequent developments. The foam clings to the top edge of the reel and prevents complete development of the film in those areas.
b)Nominal 'rinsing' will not remove all the washaid - the tank needs to be thoroughly cleaned each time.
c)A proper routine of gentle agitation should be used and adhered to.
d)The problem is more likely when the dev. tank is full of film. For example, a one-reel tank with one reel, a two-reel tank with two reels. The surface of the dev. is too close to the top of the film. Better to use a larger tank, leave some space above the reel, and use more dev. A 120 reel needs 500mls liquid to cover it. I suggest a MINIMUM of 550 mls, and better 600, to keep the dev. surface away from the top of the reels. Note that you should use something to prevent the reels from 'sliding' down the centre post whilst inverting. There is usually a white plastic stop supplied, but these get lost. An elastic band wrapped tightly round the post tight to the reel will do the trick.
Foaming and contamination had been suggested. I discounted contamination my other chemicals - just not viable, and concentrated on foaming.
I thoroughly cleaned two dev tanks in the dishwasher, then developed a roll of 120 in each tank, using partial stand agitation. Fixed and washed. In one tank I used a washaid (Kodak) and in the other alcohol and dist. water. Both films were perfect.
I then washed out both tanks by a general 'swill' with clean cold water and left them to dry.
I developed two more rolls of film, noting which tank had had the washaid in, using the partial stand method. I should point out that the agitation I use is 'gentle' - pouring the dev gently down the side of the tank during inversions and a gentle 'swirl' for lateral movement. Both films fixed and washed and washaid added to the same tank as previously. Both films perfect.
I repeated the experiment as before, developing two more films, but I was far more energetic, giving some shaking to the tanks, and inverting rather vigorously. Partial stand. Films fixed and washed, washaid in the same tank.
Eureka! The film from the washaid tank had those markings! The other film, perfect. I repeated this experiment another two times, once with gentle agitation, once with vigorous agitation and the results were the same; vigorous agitation in a tank previously having washaid in produced the marking, obviously from foaming. (which you could in fact, see, as it bubbled up through the pouring hole.) Films from a washaid-free tank always perfect.
Conclusions;
a)Washaid used in a tank can produce foaming in subsequent developments. The foam clings to the top edge of the reel and prevents complete development of the film in those areas.
b)Nominal 'rinsing' will not remove all the washaid - the tank needs to be thoroughly cleaned each time.
c)A proper routine of gentle agitation should be used and adhered to.
d)The problem is more likely when the dev. tank is full of film. For example, a one-reel tank with one reel, a two-reel tank with two reels. The surface of the dev. is too close to the top of the film. Better to use a larger tank, leave some space above the reel, and use more dev. A 120 reel needs 500mls liquid to cover it. I suggest a MINIMUM of 550 mls, and better 600, to keep the dev. surface away from the top of the reels. Note that you should use something to prevent the reels from 'sliding' down the centre post whilst inverting. There is usually a white plastic stop supplied, but these get lost. An elastic band wrapped tightly round the post tight to the reel will do the trick.