Developer stain

Owned by fixer faults, washing faults and the stains they leave. Its whole-sheet relative is oxidation stain, whose cause is in the bottle rather than on the bench.

What you see

A brown or yellow-brown mark on a print or a negative, in a shape that belongs to how the material was handled rather than to what was photographed. Four shapes recur:

• Along one edge, where a sheet stood above the solution or was laid down before it reached the stop.
• A drip or a run, where solution travelled down a hanging or propped sheet.
• A fingerprint or a tong mark, where developer was carried onto the material by something else.
• Over the whole sheet, including the borders, which is not this entry: that is oxidation stain and its cause is the developer’s own condition.

The mark is in the gelatin rather than on it, so it does not swab off and it prints.

Likely causes

1. A transfer that took too long. The seconds between lifting a print from the developer and putting it in the stop are seconds in which developer on the surface is in contact with air.
2. Material not fully covered during development, so part of it drained and dried while the rest developed.
3. Developer carried by a hand, a tong or a wet bench onto dry paper.
4. No stop bath, or a water rinse used too many times.

What is happening: the chemistry and physics

Developing agents are reducing agents, and their business is to give up electrons. Silver ions are the intended recipient; oxygen is a competitor that is always present.

When a developing agent is oxidised by air rather than by silver, it becomes a different compound — and those oxidation products are coloured, which the starting materials and sulphite’s own oxidation product are not. That is the whole of the mechanism, and it is why an old developer goes brown in the bottle and why developer left on a print goes brown on the print.

The colour lands in the gelatin because the developer was in the gelatin: the layer is swollen and full of solution, and what oxidises there stays there.

!A staining developer's stain is not a fault, and must not be diagnosed as one

Pyrogallol and catechol developers produce a coloured oxidation product on purpose, in proportion to the silver developed, adding printing density where the image is. A negative from a staining developer comes out of the process yellow-brown and is supposed to.

Two observations separate a wanted stain from an unwanted one, and both are quick.

Is it image-wise? A staining developer’s stain follows the picture: strongest where the density is greatest, and absent from the rebate, because no silver was developed there. A developer stain from oxidation on the bench follows the handling — an edge, a drip, a fingerprint — and a stain from an oxidised bath covers the rebate as thoroughly as the frame.

Is it in the record? What developer was used. If the answer is a pyro or catechol formula, the colour is the formula working.

A related trap is worth knowing because it looks like the stain getting worse: Kodak’s 1928 primer records that ferricyanide removes the silver of a pyro-developed negative but not the stain, so such a negative appears to grow yellower as it is reduced. The reducer is not making the colour; it is uncovering it.

Diagnostic questions

• What shape is it, and does that shape belong to the handling or to the picture? An edge, a drip or a print of a finger is handling.
• Does it reach the rebate or the print border? A localised handling stain does not, unless that is where it was made; a whole-sheet stain does, and points at the bath.
• What developer was used? A staining developer answers the question before any other test.
• How long between the developer and the stop? Count it on the next print; most people are surprised.
• Was the material fully covered throughout? A sheet standing proud of the solution, or a film above the liquid line, drains and dries.
• Was a stop bath used, or a water rinse, and how often had the water been changed?
• Is it on the prints handled with tongs that had been in two trays?

Corrective action

None on the material. The colour is in the gelatin and no wash removes it.

Where the mark is at an edge that can be trimmed, or on a border that will be under a mount, the print may be usable. Otherwise make it again.

Prevention

Use a stop bath. ILFORD’s own reason for recommending one is this fault by name: a stop bath “stops development immediately, reduces the risk of staining, and extends the life of the fixer bath”. Their figures are ILFOSTOP at 1+19 for 10 seconds at 20 °C, for film and paper alike.

Where a stop bath is not used, change the water often. ILFORD say plainly that substituting a water bath “increases the risk of seeing processing related marks and stains”, and that to reduce the risk “the water bath must be completely changed at very frequent intervals”.

Move promptly between baths, and do not lay a print down between the developer and the stop.

Keep the material covered. Enough solution, and a dish comfortably larger than the sheet.

Separate wet and dry. Kodak’s own darkroom layout instruction is to divide the room into a wet area and a dry area, to handle film, negatives and paper only in the dry area, and to keep a container of water for rinsing hands with a clean towel to dry them. Most stains carried onto dry paper arrive on a hand.