Temperature range to avoid mosaic effect?

[Marco Gilardetti]

Good evening fellows.

Tap water here during winter flows at mean temperatures of 4-6 Celsius degrees (near freezing point, that is). I usually avoid developing anything until April because I fear to cause mosaic effect on gelatin, not to mention the fact that the wash itself would be partly inefficient.

However, this winter I have taken pictures of my sister, who's waiting a baby, so I'd like do develop the film immediately to make sure everything is OK and eventually take the pictures again. If I wait and - say - find out that the shutter was broken, I'll have no further chance to take these pictures once again. So this time I am compelled to deal with very cold water during wash.

Let's suppose I start with a developer at 18 degrees (not the usual 20) and then wash at 4 degrees. Is this range enough already (with nowadays emulsions) to cause a mosaic effect?

In case, what should I try? Would it be better to develop with a colder developer (say 14-15 degs.), or trying to rise the wash temperature with the heater (which usually causes cycles of cold and warm water around an avarage temperature, which may be worse for the mosaic effect)?

Film is Ilford FP4 by the way. Thank you very much for reading.

[trexx]

Regardless of the temperature it is best to have all chemistry and wash be the same temperature. It is wide differences in temperature that cause reticulation, mosaic, to occur.

So set aside several liters of water in a warm place. When it has come up to room temperature, at least 18C, use it to mix the chemistry and for wash. Using the Ilford wash method you only need 1.5 liters for a .5 liter tank. ( fill 5 inversions dump, fill 10 inversion dump, fill 20 inversions dump)

[nyoung]

Marco, I would try to get my developer, fix and wash temperatures closer together than 14 degrees. Prehaps you could preheat 4 to 6 liters of wash water to 15 degrees or so. Washing under the running tap is not absolutely necessary. With 6 liters of wash water you could fill, agitate for a minute or so, pour out, and then refill 6 or more times for the typical developing can.

The mosaic effect you are talking about is generally not a result of temperature so much as it is the result of a sudden large change in temperature.

Many people don't realize this but you can "hold" film almost indefinitely by leaving it sitting in a tank of water.

You could also develop in your 20 degree developer and fix then fill your tank with water near that temperature. Then let the whole tank sit until it has cooled down enough to wash under your running tap.

[Ian Grant]

Reticulation is difficult to achieve with modern films except Adox/EFKE. However micro reticulation is a problem this increases the apparent grain and is caused by the sudden change in temperature, why not use Ilfords wash technique it uses very little water. Keep the wash within 1 ir 2 degrees of the rest of the processing.

Ian

[Marco Gilardetti]

Thanks a lot for your replies so far.

Where did you read about the Ilford technique? On their papers I've seen only the one involving the Ilford Washaid, but that requires running water as usual.

Otherwise the last paragraph written by nyoung seems the best road to travel...

[Bob F.]

Sorry - getting confused here - not sure if you mean film or paper...

For prints, RC can be soaked in 3 changes of water after 2 mins in wash-aid - change water every 5 minutes.

For fibre, a quick rinse followed by 10 mins in wash-aid followed by 3 soaks for 10 mins each in water will do the job.

The Ilford technique for film is: fill tank with water, 5 slow inversions; dump water and refill and invert 10 times; dump water and refill and invert 20 times. Some people like to repeat the 20 inversions again. It is in all Ilford's film datasheets and here: http://www.ilfordphoto.com/applications/page.asp?n=31 in the downloadable PDF.

[Ian Grant]

The Ilford wash technique is in all their data sheets for films etc. Ilford say + or - 5 degrees but really you should be more accurate than that, you can let the temperature drift down slowly.

Like Bob suggests I give slightly longer wash than Ilford recommend but it doesn't use much water.

Ian

[Marco Gilardetti]

Okay, thanks for clearing it up.

I as well, on my side, do think that's not enough for washing (without even a hypo eliminator, gosh...). Nonetheless, I'm sure adopting this technique in this specific case as I understand that a wash at 4 degs. would however be too low to really solute all the hypo in the film.

On the other hand, letting the water temperature in the tank cool down gently may be an idea I should keep in mind for mid-seasons. For some reason, I've never thought about it.

Thank you very much for your hints!

[Nicholas Lindan]

Tap water here during winter flows at mean temperatures of 4-6 Celsius degrees [how do I wash film]

It only takes 4 or so changes of water to completely wash film. For a 250ml tank you would only need 1 liter of room temperature water. 5 minutes for each wash, with good agitation - as if you were developing - is all that is needed.

Common sense might say the wash times should lengthen with each change, but in fact they should remain constant as a perusal of the equations governing diffusion processes will show. Prolongation of the wash times will have no benefit and can only harm the film. Overwashing to the extent of removing 100% of the hypo will shorten the stability of the image, a trace of hypo is desirable.

There is a lot of hysteria about washing times - like a fish story, they get longer and longer with each re-telling.

[Steve Roberts]

I have this situation through much of the winter. (When developing a roll of FP4 last Sunday the temperature of the tap water was 7 degs C.) My technique is to develop and fix at my usual 20 degs, then several short washes at progressively lower temperatures (4 or 5 degs) until I'm at ambient tap water temp, then the usual flow wash. The film stays in the water at each stage for as long as it takes me to mix water of the next lower temperature - perhaps 30 - 45 secs. Never had any problems.

Best wishes,

Steve