Water spots

Owned by the emulsion under stress. The continuous, directional version of the same physics is drying marks; this entry is the discrete-drop case.

What you see

Round or teardrop marks, individual and separated, rather than streaks. Often a ring: a paler or darker rim with a different centre, because a drying drop concentrates its dissolved solid at the edge as it retreats.

Their distribution is the tell. They are where drops landed or gathered — under a clip, along a lower edge, in a scatter across one region — rather than in the direction the film drained.

Kodak’s Z-133 distinguishes two appearances that matter here: water marks, from excess water causing differential drying, and surface spots that appear dark by transmitted light, whose causes include water spotting alongside dirt from the wetting-agent solution, dirt from the dryer, and a sulfurised fixer.

Likely causes

1. A splash onto a film already drying — from the tap, from a neighbouring film being handled, from a shelf above.
2. Drops from a clip that was in the solution and carried liquid with it.
3. A rinse that broke into drops because the wetting agent was too dilute, or absent.
4. Hard water, which leaves visible solid where a soft supply leaves almost none.
5. A dirty wetting-agent solution, which deposits its own dirt in the drop.

What is happening: the chemistry and physics

A drop sitting on a drying film evaporates from its own surface. Everything dissolved in it stays behind, concentrated into the shrinking volume, and is deposited into and onto the gelatin under it. Where the gelatin is still swollen it takes some of that solid in; where it has dried it takes it on.

The two possibilities matter, because only one of them can be removed, and the distinction is diagnostic:

• Deposited on a dry surface — a film of solid sitting proud, which catches raking light as a separate plane and which is often removable.
• Taken into a swollen layer — a change in the gelatin, in the light path, permanent.

The commonest case is a drop that landed while the film was partly dry, so it is a bit of both: a deposit at the rim and a change in the layer at the centre.

!One look tells you whether it is on the surface or in the layer

Hold the film at a grazing angle to a strong lamp and look at the surface rather than through it.

A deposit sits proud and catches the light as its own plane. It has a shine or a matt patch different from the surface around it.

A change in the layer is in the plane of the film and does not catch the light differently.

If you are still unsure, put a little clean water on a swab and touch a corner that will be trimmed. A deposit softens and moves; a change does not. That is the same test that runs through the whole of the sludges and scums discussion, and it is the one that decides whether a treatment is worth attempting at all.

Diagnostic questions

• Discrete spots or continuous streaks? Spots are drops; streaks are drainage and belong to drying marks.
• Do they have a ring structure? A rim different from the centre is characteristic of a drop that dried in place.
• Where are they? Under the clip, along one edge, in a scatter on one region — each points at a different source.
• Deposit or change, by the grazing-light test above?
• Do they appear dark by transmitted light? Kodak’s separate row for surface spots that read dark lists four causes, and three of them are dirt rather than water: a dirty wetting-agent solution, dirt from the dryer, and a sulfurised fixer. Rule those out before blaming the water.
• How hard is your water, and was the final rinse made with it?
• Was anything happening near the drying film? A tap, a wash tray, another film being hung.

Corrective action

Rewash and re-dry, once. A surface deposit will often go: soak the film, rinse in correctly diluted wetting agent, drain and dry properly. A change in the gelatin will not, and the course has no source stating which case a given spot is, so the rewash is a test as much as a treatment.

Do not use solvents or abrasives. A spot is a small fault; a solvent applied to an original is a large one.

Print it and spot the print where the mark survives. A water spot that reads dark on the negative prints light and is filled with a spotting dye; one that reads light prints dark and is harder.

Prevention

Give the film a still, closed place to dry, away from the sink, the tap and anything anyone will be handling. Most water spots are somebody else’s splash, including your own from ten minutes later.

Keep the clips out of the solutions, so nothing is carried out on them and nothing runs down.

Use the wetting agent at a measured dilution — ILFORD’s 1+200 starting point — so the rinse sheets off instead of beading. A film that beads is a film that will spot.

Use distilled or deionised water for the final rinse if your supply is hard, and note Kodak Limited’s counter-intuitive refinement: with hard water, use less wetting agent, not more.

Keep the rinse solution clean and fresh. Kodak name a dirty wetting-agent solution as a cause of surface spots in its own right, with the corrective action of dumping and replacing it routinely.