Reel and contact marks

Owned by uneven development, bromide drag and surge marks.

What you see

A pale patch with a soft edge, in a shape that belongs to the equipment rather than to the picture. On 35 mm film off a spiral it is often a smooth arc or a lens-shaped area where two turns touched, sometimes repeating where the film touched at several points around the coil. On sheet film shuffled in a tray it is a large area, sometimes most of a sheet, and often the whole of one corner.

The mark is of reduced density. It has no relation to what was photographed, and it stops where the contact stopped.

Likely causes

1. A badly loaded spiral, where the film jumped its groove and two turns lie against each other.
2. A damp or slightly warped reel, which is the commonest reason a film jumps.
3. Too much film on a reel, or two films on a reel meant for one.
4. Sheets shuffled face to back in a tray, so that solution is pressed out from between them.
5. Film or paper resting flat against the tank wall or the dish bottom.

What is happening: the chemistry and physics

The mechanism is the air bell’s mechanism at a larger scale: where solution cannot reach the emulsion, development does not happen there.

Two wet gelatin surfaces pressed together are held by surface tension and by the film of liquid between them, and that film is not exchanged with the bulk. Kodak’s statement of what agitation is for describes precisely what is failing: agitation exists to remove exhausted solution from the emulsion surface and replace it with fresh, and it must be uniform throughout the tank. Between two touching turns of film there is no exchange at all, so the small volume trapped there develops what it can and then stops.

That is why the mark is pale rather than clear. Unlike a bubble, a contact does not exclude the developer entirely — there was liquid there when the surfaces met — so the area is partly developed, and the density falls off gradually towards the edge of the contact as exchange becomes possible again.

!Contact mark, cinch mark, scratch: three faults, three signatures

These three are confused constantly and the fixes are unrelated.

	Density	Shape	Feel	Made when
Contact mark	Less	Broad, soft-edged arc or patch	Nothing	In the tank
Cinch mark	More	Sharp crescent, millimetres	Nothing	Before development — loading or the camera
Scratch	Either	A line	A groove you can feel or see under a loupe	Anywhere; the side says where

The single most useful discrimination is the direction of the density change. A contact mark is less developed; a cinch mark is more, because mechanical pressure on an emulsion before development makes the pressed region more developable. Kodak’s table lists cinch marks under plus-density pressure marks for exactly that reason.

Diagnostic questions

• Is the mark paler or darker than its surroundings? Paler is contact; darker is pressure.
• Does it have a soft edge? Contact marks do. A sharp edge means a bubble or a physical mark.
• Does its shape match the reel? Lay the film back on the spiral and see whether the patch falls where two turns would meet. This is the confirming test and it takes a minute.
• Is it on more than one frame, at intervals? A film that jumped its groove usually touches at more than one place around the coil, at intervals set by the coil rather than by the frames.
• On sheet film, was the batch shuffled? And how many sheets in how much solution?
• Was the reel completely dry when it was loaded? A reel that feels dry to the hand can still be damp in its grooves.

Corrective action

Nothing on the negative, for the same reason as every under-developed area: the silver was never formed.

If the affected area is outside the picture, or in a region that can be printed down, the frame may still be usable. Otherwise it is a reshoot.

Prevention

Dry the reel completely and check it before loading. A warm airing cupboard for an hour, or a hairdryer on cool. This single habit prevents most of them.

Load in a bag rather than in a hurry, and feel the film into both grooves at the start rather than trusting the first two turns.

One film per reel, and enough solution: ILFORD’s own worked example for one 35 mm film in a spiral tank is 300 mL, and a tank that does not cover the film completely produces this fault at the top of the spiral every time.

With sheet film, use hangers or a slotted tank rather than shuffling where you can; where you must shuffle, use fewer sheets in more solution and take each sheet from the bottom by an edge rather than by sliding it.

Agitate. Uniform agitation, as Kodak’s requirement puts it, is what breaks a contact that has just formed; a film left still for a long stand is a film given time to settle against itself.