Reticulation

Owned by The Emulsion Under Stress, which places this fault in the layer rather than in the image, leaves open the question of how large a shock a modern hardened film needs, and points back here for the dispute in full. It gives the same free discriminator against clumped grain — tilt the film against a lamp and look at the rebate — and ILFORD’s published tolerance of 5 °C between process solutions. This entry was written earlier from diffusion, swelling and the journey into the emulsion.

What you see

A coarse wrinkling over the whole layer, visible in reflected light and, in severe cases, as a texture that prints. In its extreme form the layer detaches from its support altogether, which is frilling arriving by the same route.

It has no direction and no relationship to the picture, because it is a property of the gelatin rather than of the image in it.

Likely causes

1. Solutions at sharply different temperatures, so that the layer expands or contracts suddenly as it moves between them.
2. A bath run at an extreme temperature.
3. A layer that is unhardened or only lightly hardened taken through a large temperature step.

What is happening: the chemistry and physics

Gelatin is a colloid that swells rather than dissolves in cold water, and the amount it swells depends on what is dissolved around it and on the temperature. Move a layer from a concentrated bath to plain water and it takes up water and expands; move it the other way and it gives water up and contracts.

Kodak’s 1928 primer names the failure precisely — all solutions must be kept at the same temperature “in order to avoid sudden contractions or expansions of the gelatin which may result in detaching the film from its support or in the production of reticulation, i.e., a coarse wrinkling all over the film”.

The primer’s context is often dropped and it matters. It is discussing what happens “when photographic materials are exposed to extreme temperatures”, and its prescribed control is a hardener in the fixing bath.

⁇Can a modern film actually be made to reticulate?

Nobody disputes the mechanism set out above. What is disputed is whether an ordinary difference between two bath temperatures can still reach it on a film that was hardened at manufacture.

Kodak’s 1928 primer describes reticulation as a real risk with the materials of its day, under extreme temperatures, and prescribes alum hardening against it. Modern practitioners frequently report being unable to produce it deliberately on current films, and it is often described in current writing as largely historical.

The course has not found a modern manufacturer statement establishing either position, and so does not pick one. It teaches the mechanism, which is certain, and does not claim that your film will or will not reticulate at a given temperature difference. Both positions agree on the control, which is the useful part.

Diagnostic questions

• What were the actual temperatures of all four baths, and of the wash? Not the intended temperatures — the measured ones. This is the question the fault is about.
• Is the wrinkling over the whole layer, including the rebate? It should be, because it is a property of the gelatin and not of the exposure.
• Was the material hardened? An unhardened hand-coated layer is far more exposed to this than a modern film.
• Is the edge lifting as well? Then the same stress has produced frilling and you have one cause and two symptoms rather than two faults.

Corrective action

None. A reticulated layer has set in its new shape and there is nothing to return it to.

The batch, though, is worth saving. Bring the remaining baths and the wash to a common temperature before processing anything else, and record what the spread had been.

Prevention

Keep the baths close in temperature. That is the one control both sides of the dispute agree on, and it prevents frilling at the same time.

Manufacturers publish tolerances and they are not consistent with each other. ILFORD asks for wash water within 5 °C of the process temperature for film and, on another sheet for another product line, for all process solutions within 1 °C of the temperature in use. The course does not reconcile them, because neither sheet says what it is protecting against — but the tighter figure is the safer habit and neither is difficult with a bench thermometer.

A hardening fixer is the historical control and remains available, with the caution that hardening a layer interferes with the penetration of the baths that follow.