pre soak

[12pmc]

I am sure its been asked before, but what is the thing with pre soaking film before development. Is there any real reason to do this or not, do some films benefit and some not?

Peter

[Gudmundur Ingolfsson]

Presoaking helps you develop evenly. Think of your dry unprocessed film as a dry sponge. When you have filled your film (your dry sponge) with water the developing chemicals can reach it faster and more evenly than if it was dry. I can say that every film benefits from being presoaked (even ILFORD films, but ILFORD say they have incorporated a wetting agent in their in their film coating to make presoak unnecessary) but you might have to adjust your developing time slightly.

[Mark Woods]

The only film I really need to pre-soak is the 8x10 (and I use Ilford). I now pre-soak all films when I develop them.

[lfpf]

When shuffling more than one, pre-soaking (1 minute, or so) keeps dry emulsion/film from sticking to other developing films. Pre-soaked films shuffle easily. Spacing sheets by 10 seconds or so in the soak tray seems effective while paying attention to sticking. If sticking occurs, then add more soaking time between additional sheets. As mentioned, Ilford may have solved the dry emulsion sticking problem.

Sequenced two bath developing (A-developer only, B-activator) may have other needs.

Steve

[12pmc]

Thank you all - connected to the water question, does water hardness have an impact on the development of the negative?

[Daniel Stone]

Thank you all - connected to the water question, does water hardness have an impact on the development of the negative?

Try this:
Do a self-experiment. Compare identically exposed negatives, processed in identically-mixed developer solutions, developed for the same time/temperature/etc. Only difference being that one developing solution is mixed with distilled water, and the other is mixed with your local tap water

[lfpf]

Thank you all - connected to the water question, does water hardness have an impact on the development of the negative?

Emulsion swelling and development activity depends on pH and tap waters vary widely in pH. Also, distilled water may causes excessive (pre-soak) emulsion swelling (unconfirmed rumor). A reference would be useful here and ideal mixing water pH may be a non-issue if b/w developers are buffered. Some of this is foggy recollection, so I'll research a bit and report findings.

Other members (chemists) will know more.

Steve

[12pmc]

Steve - thanks for that info, I would like to know what the ideal ph is for development of film. The water in our area is very hard, and while the impact on my negaitves may be minor, it would be good know. If there is any reading I can do on this can you point me in the right direction?

Peter

[lfpf]

Steve - thanks for that info, I would like to know what the ideal ph is for development of film. The water in our area is very hard, and while the impact on my negaitves may be minor, it would be good know. If there is any reading I can do on this can you point me in the right direction?

Peter

Ideal pH is an interesting concern. While pH is certainly a factor, buffers and alkalis are on your side.
Peter,

Generally speaking, potable water is suitable for photographic purposes. Working in the developer's favor are "buffers", a useful search term. An area library may have a copy of Modern Photographic Processing Volume 1 by Grant Haist. Informative and to the point is Chapter 5, The Function of Developer Constituents Development is a fairly complex heterogeneous reaction, the mechanism of which is not completely understood., K. S. Lyalikov

Searchable Sleeping Pill #1
https://archive.org/stream/TheTheory...ge/n7/mode/2up
Searchable Sleeping Pill #2
https://archive.org/stream/photograp...ge/10/mode/2up
A local library system may also have other reference materials.

What does your municipality report for water hardness? Third-hand Kodak information indicates water hardness between 40 and 150 mg/L is suitable for darkroom applications. With luck, your tap water is excellent for mixing with no concerns.

The following is copied from
http://motion.kodak.com/motion/uploa...2415_h2415.pdf

Water Quality
A supply of good quality water is very important to motion-picture processing. Although tap water may contain some impurities, most impurities have no photographic effect. Those you should be most careful of include large quantities of suspended organic matter, hydrogen sulfide, particles of finely divided sulfur, and soluble metallic sulfides. These can cause serious trouble with developers. Fortunately, these impurities are not common to most municipal water supplies.
Processing Black-and-White Films page 15-7:
Organic matter usually precipitates on mixing the developer, but biological growths and bacteria can thrive in developer solutions, forming a slime or scum on the walls of the tank. Certain types of these growths act on the sulfite in the developer and change it to sodium sulfide, a chemical which fogs the emulsion. Proper agitation and cleaning the developer tank frequently will prevent this. If alum carries into the wash water from the fixer, organic matter already in the water coagulates and settles on the film. You can avoid this by filtering the water, or by adding boric acid to an acid fixing bath (up to a maximum of 15 grams per litre).
Extremely hard water may produce a finely divided precipitate when you mix the developer solution. The precipitate usually settles on standing, but even if it remains in suspension, it has no adverse photographic effect. If the precipitate is objectionable, add KODAK Anti-Calcium or Quadrofos. You may also see a fine precipitate when you use certain developers even though they were clear when mixed. This is normal and does not indicate poor mixing or impure water. Again, it has no adverse photographic effect.
A chemical analysis of the water supply usually reveals very little concerning its photographic usefulness. The most useful test is to prepare the required photographic solution with the suspect water sample and actually try it. Compare your results with those obtained with the same solution prepared with distilled water. In most cases, both of the solutions will be alike in their photographic effect, even if not in appearance."

[John Olsen]

Thank you all - connected to the water question, does water hardness have an impact on the development of the negative?

Under extreme conditions, definitely yes. Our mountain well had really hard water that could turn emulsions to muck. I used reverse osmosis water from the store for mixing chemicals and rinsing film. I don't know about the effects of moderately hard water.