Volume \ flow rate for RC print wash

[peter brooks]

Hopefully someone has addressed this same issue.

My darkroom (in a converted garage) has cold water only from a mixer tap. (One day...) So I process film using multiple thermos flasks of pre-mixed water, and this works well.

I'd like to get back to developing prints, predominately for paper negatives at present using resin coated (Ilford MG) paper.

I'm thinking I could use a plastic plumbing tank (or simply a plastic storage box) as a reservoir to hold pre-mixed water for the wash, with an outlet valve to control the flow, and gravity to take it down to a tray or print washer in the sink.

The Ilford documentation has very little detail on the wash requirements:

Fresh, running water above 5ºC / 41ºF
Time 120 seconds

When it is important to obtain a print in the shortest possible time, vigorously wash ILFORD resin coated papers for 30 seconds in running water.

Prolonged immersion in water can cause edge penetration and print curl with resin coated papers: for this reason, avoid wet times longer than 15 minutes.

I'm aware that RC papers require far less washing than fibre but I'd be grateful for any thoughts on the volume of water and flow rate required.

And if you've done this yourself, using either a tray or a multi-print washer unit, what was your experience?

Many thanks,
Peter

[Michael R]

You don’t really need running water with a constant flow.

Washing is a diffusion process. Fixer and related complexes diffuse out of the emulsion/paper into the thin layer of water at the paper surface. As that layer becomes saturated it needs to be removed and replaced. This needs to be done several times (much fewer with RC paper). Running/flowing water, if done properly, accomplishes this without manual intervention, which is the convenience factor. However if one doesn’t have running water, and/or doesn’t mind a little effort, the wash can be done just as effectively with far less water by doing soak/agitate/dump cycles.

Best idea would be to test for residual fixer to see if you are getting a good wash, and then you’ll have your procedure going forward.

[Doremus Scudder]

Ilford says 2 minutes for RC papers in running water in their "Processing Summary." The 30-seconds-with-lots-of-agitation regime is for "down-and-dirty" quick print processing for situations with deadlines (think newspaper, etc.). I'd stick with 2 minutes or a little more.

As for flow rate: I'd think that if the wash time were only 2 minutes, I'd like a full change of water in that time. You can minimize your water usage by keeping a small volume in the wash tray; less water to change means less water used overall. One 8x10 tray with a liter of water in it could serve as a holding tray for a number of prints. When ready to wash, transfer them to the wash tray with a liter of fresh water in it as well. Agitate for a few seconds then start the flow and open the drain (this assumes you've rigged up an inlet of some kind, like a hose with holes in it and have a drain - I like a series of small holes drilled in the corner of the tray on the short side. This can be blocked with tape, etc. when not needed and then uncovered when the drain is required - adjust the number of holes uncovered to adjust flow rate). Set your flow rate to give you at least one liter during the 2-minute wash. Agitate your prints during the wash. After two minutes stop the drain and shut off the input when the tray has a liter of water in it. Then you're ready for the next batch. Refresh the water in your holding tray too.

Five or six liters of tempered water should wash a fair number of prints.

If you have access to tempered running water elsewhere, you can always just do the down-and-dirty wash, dry the prints, take them to another location and wash and re-dry there.

Best,

Doremus

[Greg Y]

Peter, Even though i have running water in my darkroom, I fill a bucket & several plastic dishpans with tempered water at just over 20 C. I use the tray method soak, agitate, change ...
I use FB paper, but for RC it will take very little time/ changes to get an effective wash.

[peter brooks]

Thanks all for the suggestions and advice.

At a previous house I used to use a spare tray and a shower head in the bath - that was certainly vigorous agitation (effervescing even) and after three or four changes of water I felt intriniscally happy that they were well washed. (Fibre I used to fill two cool boxes with warm water and give the prints a good long soak in each, after a 'holding bucket', and before a final tray spray / dump cycle with the shower head).

I am getting lazy and am looking for some very basic automation so I could be doing other things - Doremus, your scheme sound like a good one.

Never really thought of it before but 5ºC / 41ºF is really quite cold (I'm so used to 20ºC being the by-word). I'll have to take the temperature after running the water for a while, maybe the cold flow from the mixer tap would do, put through something to distribute the flow a bit better.

[_tf_]

Never really thought of it before but 5ºC / 41ºF is really quite cold (I'm so used to 20ºC being the by-word). I'll have to take the temperature after running the water for a while, maybe the cold flow from the mixer tap would do.

Up here in Scotland the tap water doesn't seem to ever get much colder than 10C, the pipes are just too deep in the ground; just now it's about 18C and for a bit in the summer it got up to 21C, which was annoying for mixing my film developers. I use the Nova ECO washer straight from the cold tap (the Nova is great for a small darkroom because of space efficiency).

My darkroom also only has cold water supply, so I fitted a small (3kW) flow water tap; the flow is quite small but you can get water up to about 45C from it, great for mixing chemicals and washing hands, I am really glad I did that.

[Doremus Scudder]

Keep in mind that a lower wash-water temperature will really slow down the washing and increase the wash time. If you want to save water and time shoot for 20°-22°C (68°-72°F). The washing efficiency drops off rather quickly as the temperature gets lower than that.

Doremus

[esearing]

Use a holding tray in the darkroom then take the prints inside to do final wash where you can use hot and cold running water drip to achieve desired temperature. 12x16 trays will easily hold a gallon of initial wash/soak water and 6-8 8x10 prints float around nicely, but I still flip through them when adding next print. Most of the prints will sit in the holding tray for up to an hour then I tend to wash in running water for 15-30 minutes. Another tip - failed test strips and bad prints do not need to be washed to archive permanence before you throw them away.

[Tin Can]

You are washing RC 30 minutes!

5 minutes is too long

https://www.ilfordphoto.com/amfile/f.../product/2019/

Use a holding tray in the darkroom then take the prints inside to do final wash where you can use hot and cold running water drip to achieve desired temperature. 12x16 trays will easily hold a gallon of initial wash/soak water and 6-8 8x10 prints float around nicely, but I still flip through them when adding next print. Most of the prints will sit in the holding tray for up to an hour then I tend to wash in running water for 15-30 minutes. Another tip - failed test strips and bad prints do not need to be washed to archive permanence before you throw them away.

[Greg Y]

You are washing RC 30 minutes!

5 minutes is too long

https://www.ilfordphoto.com/amfile/f.../product/2019/

What Tin Can said, RC prints require very little wash time. & esearing a great point about not archivally washing test strips & failed prints, i have been guilty of that. I only work with FB and it runs into a lot of time & water.