Grey highlights from developer exhaustion, as distinct from fog

Owned by Print Developer Chemistry and the Developer-Paper Pair, which separates capacity from exhaustion and explains why a print developer is spent by the work rather than by the air, and by Break/Fix — the print that will not go black, whose developer differential names this entry for the one outcome in which a doubled development moves neither end of the scale. Developing the print consistently owns the shape of the decline across a session. This entry was written before all three, from the manufacturers’ capacity tables and from the film-side exhaustion work the course already had.

What you see

A print that will not go white and will not go black. Highlights sit at a flat light grey rather than paper base, maximum black is a dark grey, and the image takes noticeably longer to appear than it used to. Print colour often shifts warmer at the same time; Kodak note that developer contamination or exhaustion causes image-colour variations.

The whole scale has moved inwards, which is the thing to hold on to. Compare it with developer fog on paper, where the whites go grey and the blacks stay black, and with paper storage fog, where the whites were grey before the sheet reached the dish.

Likely causes

1. Capacity used up. ILFORD publish it plainly: one litre of MULTIGRADE developer at 1+9 develops 100 8 × 10 inch RC prints or 50 fibre-base prints; at 1+14, seventy and forty. PQ Universal at 1+9 gives seventy and forty-five, and BROMOPHEN at 1+3 the same. Roughly half those figures if you are printing MULTIGRADE RC COOLTONE, because its development times are longer.
2. A bath left standing. An open dish oxidises between sessions even when nothing is printed in it.
3. Over-dilution. A working strength chosen for economy is a working strength with less to give.
4. Cold. A bath below its range develops slowly and looks exhausted, and this is the one cause on the list that a thermometer eliminates in ten seconds.

What is happening: the chemistry and physics

A print developer does far more work per unit area than a film developer, because a print is mostly black and a negative is mostly not. So it exhausts on the work rather than on the air, and its decline is faster and more predictable than a film developer’s — which is why manufacturers can publish a capacity in prints rather than in months.

Two things are consumed and they are consumed unevenly. The developing agents are oxidised as they reduce silver, and once enough of them have gone the reaction cannot complete in the time available. Sulfite holds the oxidation products in check until it too is spent. Meanwhile bromide accumulates, released from every grain that develops, and bromide restrains — most of all where there is least silver.

That combination explains the appearance exactly. Blacks fall because development cannot complete. Highlights rise, or fail to fall, because the paper needs more exposure than it did and the printer has not given it. The result is a compressed scale in a bath that is still, technically, developing.

!The confirming test: an unexposed sheet, and a fresh dish

Two sheets and one comparison, and it separates the three faults that look alike.

First, develop an unexposed sheet fully in the working bath.

• It goes grey: the bath is fogging, and the fault is developer fog on paper, not exhaustion.
• It stays white: the bath is not fogging. Exhaustion remains.

Then re-print the same negative at the same exposure in a fresh bath at the correct dilution and 20 °C.

• The blacks come back: exhaustion confirmed.
• They do not: the fault is exposure, contrast grade or the negative, and the developer was never the problem.

One more check settles cold against spent: read the bath’s temperature. ILFORD’s figure for a correctly exposed fibre print is that the image begins to appear after 35 seconds; a bath in which it takes much longer is either cold or tired, and only one of those is fixed with a jug of warm water.

Diagnostic questions

• How many prints has this litre done, at what dilution, on what paper? Against ILFORD’s table, not against a feeling.
• How long has it been in the dish? ILFORD tell a beginner to mix only enough to half fill the dish and pour it away after the session, which is advice about oxidation as much as economy.
• When does the image first appear? Thirty-five seconds is the published expectation for a correctly exposed fibre print in these developers.
• Is the temperature right? The cheapest question on the list.
• Did the image colour shift as well? Kodak name exhaustion and contamination together as causes of image-colour variation, which makes a warm shift corroborating evidence rather than a separate fault.

Corrective action

Fresh developer. There is no other fix and there is no reason to look for one: a litre of working solution is among the cheapest things in the darkroom, and a session’s prints are not.

Do not compensate with time. ILFORD note that on correctly exposed fibre prints development may be extended to six minutes without noticeable change in contrast or fog — which is a statement about a sound bath. In an exhausted one, extra time buys unevenness and a warmer tone rather than a better black.

Re-print the reference print in the fresh bath before continuing, so the session has a known starting point.

Prevention

Count. ILFORD’s capacities are per litre and per size; a tally sheet beside the dish is the whole discipline.

Mix for the session and discard, which removes exhaustion and standing oxidation in one habit.

Keep a reference print from a known negative at a known exposure, and remake it at the start of each session. A bath that has drifted shows up on it before it shows up on new work.