Presoak

From Silvergrain Labs

Whether to presoak

Presoaking is a step to wet the film in plain water prior to development. There are some reasonings for and against presoaking:

Pros:

• It stabilizes temperature of the film and the processing tank.
• If performed properly, it wets film surface evenly and completely, so promoting even development in the developer.
• It removes debris that may be adsorbed on the film.
• It removes some sensitizing dye in the film.

Cons:

• Films contain wetting agent to promote even wetting in the developer, but this wetting agent is removed.
• Presoaking is usually unnecessary and requires extra step.
• Presoaked films require up to 1 full minute of extra development time to reach equal contrast, and manufacturer's published development time are usually for dry films.

I have tried both ways from time to time, and I used to recommend against presoaking for the reasons above.

Airbell problems

However, I recommend presoaking for following cases:

• small tank processing of films loaded in spiral reels
• modern films that cause excessive bubbles in the developer

The reason is that, many modern films contain a large amount of anionic surfactant to facilitate rapid coating of the emulsion at low coating defect rate. These anionic surfactants are water soluble, so they dissolve into the developer. When the tank is agitated by inversion, the surfactant helps to make a lot of bubbles in the tank, to fill some of the top air space. Some of the bubbles are trapped between the film surfaces in the spiral reel, and they are hard to dislodge or collapse by tapping the tank, since there are so many bubbles and also because the head space is filled with bubbles. This is often seen as lighter spots, often in clustered circular spots appearing near one edge (the top edge during the development) of the film.

Since the surfactant is water soluble, presoaking will remove much of it from the film, and so the developer stays largely bubble-free.

PROCEDURE

1. Prepare penty of plain water at the development temperature
2. Fill the tank with the water
3. Continuously agitate for 2 minutes, tap the tank
4. Wait for 2 minutes
5. Continuously agitate for 1 minute
6. Drain the water (you may see some color in the water---that's normal)
7. Follow with the normal development procedure, but extend the development by 30s to 1m.

Persistent Airbell problems

There are a couple of films that are notorious for persistent airbell problems refractory to usual presoak and agitation protocol. As far as I am aware of, Fujifilm Neopan Acros 100 and Ilford HP5 Plus in 35mm and 120 can cause this problem. This problem may be specific to emulsion's batch number.

These films produces A LOT of bubbles due to high degree of surfactant released from the film, and the airbell mark seems to be very common with this film. For these films, I recommend two stages of presoaking to make sure that the airbell mark does not appear on the developed film!

1. Prepare penty of plain water at the development temperature
2. Fill the tank with the water
3. Continuously agitate for 1 minute, drain (you may see some color in the water---that's normal)
4. Fill the tank with fresh water
5. Continuously agitate for 1 minutes, tap the tank
6. Wait for 2 minutes
7. Continuously agitate for 1 minute
8. Drain the water
9. Follow with the normal development procedure, but extend the development by 30s to 1m.