Poor maximum black

Owned by print faults and poor maximum black as a defect; Part XVIII owns the break/fix session and Part XIX owns the printing technique. See also weak or grey blacks, which is the same family read from the other end.

What you see

On a test strip, the steps stop getting darker, and the tone they stop at is not black.

That is the whole identification, and the observation to make is not how dark the darkest step is but whether the steps are still changing. Three cases look similar and only one of them is this entry:

On the test strip	What it is
Steps still climbing at the darkest end	The print is simply too light; give more exposure
Steps stop climbing, below black	This entry: the ceiling has moved
Steps stop climbing at black, with no separation just above it	A contrast and placement problem, not a maximum-black one

Likely causes

In the order worth checking, which is roughly cost against likelihood:

1. A test strip too short, so no ceiling has actually been demonstrated.
2. A developer exhausted, too cold, too dilute, or given the wrong time for its dilution.
3. Development cut short.
4. Fog on the base, from the safelight or the room.
5. Over-fixing.
6. A contrast filter used without re-establishing the base exposure.
7. Paper that has aged.

What is happening: the chemistry and physics

Maximum black is a reflection density limit set by the paper, its surface, the developer and the drying. It is a property of the material and the process, not a number the printer can exceed.

The published figures are lower than most people guess and are worth knowing as the reference: ILFORD publish 2.15 for MULTIGRADE RC DELUXE and 2.05 for the paper it replaced; Foma publish 2.0 for FOMATONE MG Classic glossy and, on the same sheet, 1.6 for the matt surface of the same paper. A matt print is not a glossy print that failed.

Anything that lowers the amount of silver developed in the deepest tones lowers the ceiling, and there are three routes:

• Not enough development. The deepest tones are the slowest to complete, so a short, cold or weak development takes the black end first.
• Silver removed after development. Over-fixing dissolves image silver, and the deepest deposits lose a little while the highlights lose a lot.
• Nothing wrong with the black at all, but a raised white. Fog does not lower the maximum black; it raises everything below it, so the difference between paper white and black falls — and that difference is what the eye reads as depth.

!Two published numbers that settle two of the seven causes on their own

Development. ILFORD state that the image begins to appear at approximately 20 seconds on fibre paper in MULTIGRADE 1+9, that the recommended time is 1½ to 3 minutes, and — the sentence that closes the argument — that development “can be extended up to 6 minutes without any noticeable change in contrast or fog”.

So a paper developer is worked to completion by design. There is no compensating trade to be made by developing longer, and equally no penalty for giving the full time. A print pulled at 45 seconds is under-developed and nothing recovers it. Their RC sheet says the same thing directly: prints developed for shorter times “may be underdeveloped and lacking in contrast and density”.

Fixing. ILFORD RAPID FIXER at 1+4 gives fibre paper 1 minute and RC 30 seconds, against 2 to 5 minutes for film — and there is “no benefit in extending fixation beyond the recommended time” because of image etching. A printer using the film time on paper is over-fixing by two to five times, out of caution.

Between them these two numbers account for a large share of every poor black in a home darkroom, and neither needs any equipment to check.

Diagnostic questions

Ask them in this order, because the cheap ones constrain the expensive ones.

1. Extend the test strip by two more steps. Are they still getting darker? If so, this is underexposure and there is no ceiling to explain.
2. What is the developer’s temperature, dilution and running total? ILFORD’s capacity is 50 sheets of 8 × 10 fibre per litre for MULTIGRADE at 1+9, and 1+14 has its own longer time.
3. How long was the development, against the published range?
4. Is the paper’s white clean? A grey border or an unclean base points at fog, and ILFORD warn that low-level safelight fogging shows “not as safelight fog, but only as a general loss of photographic quality, particularly reduced contrast and lack of clear highlights”.
5. What was the fixing time, against the paper time?
6. Was the base exposure re-established after the grade was changed?
7. How old is the paper and how has it been kept? ILFORD give two years in excellent condition, cool and dry, in the original packaging.

Corrective action

Nothing on the print. Make it again with the cause corrected.

The one exception is case 1, which is not this fault: if the steps were still climbing, more exposure is the whole answer.

Prevention

Give the full development time. It is free, the manufacturers say six minutes costs nothing, and snatching is the commonest single cause.

Fix for the paper time and write it on the bottle, per material.

Keep a running total on the print developer against the published capacity, and mix fresh for a session that matters — working-strength paper developer in an open dish “should not be kept for more than one working day”.

Test the safelight and label the lamp, per Part XVI.

Re-establish the base exposure whenever the grade changes.

And measure your paper’s black once, so that “poor” is a comparison rather than an impression: expose a sheet to full room light, develop it fully, and keep it. That is your paper’s ceiling under your process, and every subsequent judgement is against it.