Insufficient solution volume

Owned by uneven development, bromide drag and surge marks.

What you see

Three appearances, and one bath can give you all three at once.

A tide line. A sharp horizontal boundary across the film, with everything above it thin or clear and everything below it normal. On a spiral tank this is the top of the liquid; on the last film of a two-reel tank it is the reel that stood proud.

Unevenness rather than a boundary, in a dish: a print whose tone drifts across the sheet, worst where the layer was shallowest.

A bath that failed before its published capacity. Half the volume does half the work, and a worker who scales a bath down without scaling the capacity down with it runs out early and blames the chemistry.

Likely causes

1. A tank filled by eye rather than measured.
2. A two-reel tank run with one reel and the one-reel volume, so the film sits above the liquid.
3. A dish with too shallow a layer for the size of print.
4. A volume reduced for economy without the capacity reduced with it.
5. Evaporation and carry-over over a long session, which Kodak’s Z-133 names among the nine causes of an out-of-control process in its own right.

What is happening: the chemistry and physics

Two separate consequences, and they are worth keeping apart because they need different corrections.

Coverage. Emulsion that is not in the solution does not react with it. Above the liquid line there is no development and, later, no fixing; the halide is removed by whatever fixer does reach it and what remains is clear film with a hard edge. The edge is sharp because a liquid surface is sharp.

Reservoir. Even where the film is covered, the amount of developing agent available matters. A litre holds twice the agent of half a litre, so the concentration falls half as much for the same amount of silver reduced, and the local depletion over a dense area is replenished from a larger pool. Kodak’s own statement of what agitation is for — replacing exhausted solution at the emulsion surface with fresh — has an unstated premise, which is that there is fresh solution to replace it with.

!The manufacturers state the volume rule twice, in the same words

ILFORD give the same instruction on the paper-developer sheet and on the chemical sundries sheet: make up enough solution “to fill a dish/tray to a depth of about half full or to cover the films in a spiral tank completely or fill a deep tank”.

Three clauses, three vessels, one rule: the material is completely covered and the layer is not thin.

And the worked example on the first-film guide is the number to start from: one 35 mm film in a spiral tank takes 300 mL of each solution — 60 mL of concentrate and 240 mL of water for the developer at 1+4, 15 mL and 285 mL for the stop at 1+19, 60 mL and 240 mL for the fixer at 1+4.

There is a fault at the other end too, and Kodak names it: an excessively high solution level appears in their table against chemical splash marks, with the note that the wash level should be higher than that of the other solutions. A tank filled to the brim has nowhere for the liquid to move and splashes between vessels; a wash lower than the baths before it lets solution run back down the film.

Diagnostic questions

• Is there a sharp horizontal boundary? Then measure the tank’s volume against the maker’s figure before anything else. This is not a subtle fault and it does not need a hypothesis.
• Was the volume measured or judged? A graduate, not a glance.
• How many reels were in the tank, and how many films? A tank sized for two takes the two-reel volume even with one film in it, or the empty reel must go on top.
• In a dish, how deep was the solution? Half full is the published answer.
• How much came out at the end compared with what went in? A large shortfall over a session is carry-over and evaporation, and it is worth knowing.
• Did the bath fail early? Compare what you actually made up against the capacity you assumed.

Corrective action

Nothing on the affected material. An area that never met the developer carries no image.

Where the tide line falls in the rebate or between frames, the pictures may be untouched — check before discarding.

Prevention

Measure the volume, every time, with a graduate. This is one of the very few faults in this part that is prevented completely by one habit.

Write the tank’s volume on the tank. In chinagraph or on a label: the one-reel figure and the two-reel figure, so that it is not a calculation at three o’clock in the morning.

Put an empty reel above the film in a two-reel tank, or use the two-reel volume. Both work; guessing does not.

Scale the capacity with the volume. Half a litre has half the capacity, not the same capacity in a smaller vessel.

Fill the dish to half its depth, and use a dish comfortably larger than the paper.

Keep the wash level higher than the processing baths, per Kodak’s own note, so that nothing runs back along the material.