Developer fog on paper

Owned by Break/Fix — the print that will not go black, whose double-time print separates this fault from the two it resembles in a single sheet: doubling the development brings the blacks up and the whites with them when the bath is fogging, brings the blacks up alone when the bath is merely slow, and moves neither end when it is spent. The chemistry it rests on is print developer chemistry’s. The register assigns this row to Parts XVI and XVII, and the written Part XVI hands the fault on rather than keeping it — its boundary is that grey whites are its territory and dull blacks are not, and a developer that fogs an unexposed control sheet has left the room’s differential altogether. This entry was built earlier from Part VIII’s developer chemistry applied to paper.

What you see

Whites that go grey as development continues, and a print that gets muddier rather than richer the longer it stays in the dish. Left long enough, the borders under the easel blades take a tone as well, which is the tell: the blades masked light, not developer.

That last observation is the diagnostic and it separates this entry cleanly from paper storage fog, where the border was already grey before the sheet entered the dish.

Likely causes

1. Far too long, especially warm. ILFORD’s own figures for MULTIGRADE IV RC DeLuxe are one minute at 20 °C in MULTIGRADE developer at 1+9, or two minutes in PQ Universal at 1+9. Development to completion is not development without end.
2. Too concentrated, or too alkaline. Both raise activity, and activity is what makes an unexposed grain developable.
3. A print developer short of restrainer, whether because it was mixed without one or because the formula never had one.
4. Contamination or exhaustion. ILFORD warn that a trace of fixer or stop bath in the developer gives inconsistent results, or at worst completely blank prints; and a developer used past its published capacity is a different solution from the one on the label.

What is happening: the chemistry and physics

A developer is a reducing agent that has to distinguish a grain carrying a latent-image centre from one that does not, and that distinction is kinetic rather than absolute. Exposed grains develop faster. Unexposed grains develop too, eventually. Part VIII owns the mechanism; what belongs here is the consequence for a print.

Everything on the cause list moves the same lever. More time lets the slow reaction catch up. More warmth speeds both reactions, and the unexposed one has more room to gain. More alkali raises the concentration of the active, dissociated form of the developing agent. Each narrows the margin between the two populations, and fog is what appears when the margin closes.

The restrainer is what holds it open. Bromide and organic antifoggants such as benzotriazole suppress development, and they suppress it hardest where there is least silver to develop — which is exactly the unexposed grain. A print developer that has lost its restrainer, or never had enough, has lost the thing that was keeping its whites white.

!The confirming test: develop a sheet that never saw light

Take an unexposed sheet from the box, develop it for the full time in the working bath, fix and wash it, and look at it against a fresh sheet.

• It goes grey: the developer is fogging, and the cause is in the dish.
• It stays white: the developer is not fogging, and the grey in your prints came with the paper or with the room. Go to paper storage fog and room light leak.

Then split “too far” from “wrong bath” with a second sheet developed for the recommended time only. If the short one is clean and the long one is grey, nothing is wrong with the chemistry and the fix is a timer.

Diagnostic questions

• How long, at what temperature, at what dilution? All three, in the notebook, against the published figures for the paper you are using.
• Are the easel-blade borders toned? Toned borders mean chemical fog. Clean borders with grey highlights mean something optical.
• How many prints has this litre done? ILFORD publish a capacity table in 8 × 10 inch prints per litre for each dilution; a bath past it is a different developer.
• Was the bath mixed today? ILFORD’s own instruction for a beginner is to mix only enough to half fill the dish and pour it away after the session.
• Any chance of carry-over? Two pairs of tongs, never interchanged, is the cheapest insurance in the room and its absence is the commonest reason for this fault to appear suddenly.

Corrective action

Fresh developer, correct dilution, published time, measured temperature. Four changes, but they are the four the manufacturer specified and going back to them is not an experiment.

If fog persists in a fresh bath at the published time, add a restrainer knowingly: Part VIII owns the chemistry and benzotriazole the substance. It costs paper speed and shifts image tone, and the course states the trade rather than a dose it has not measured for your paper.

Do not compensate by pulling the print early. That trades fog for a snatched development, which is a different fault with a worse-looking result.

Prevention

Time and temperature, written down. A print developer at a published time is a controlled process and a print developed “until it looks right” is not.

Mix for the session and discard, which removes exhaustion and oxidation together and is what ILFORD tell a beginner to do.

Separate tongs, separate dishes, labelled. The contamination route is the one that turns a working darkroom into a puzzling one overnight.