One-shot Wash Aid?
A question for the chemically inclined....
Given that there seems to be no practical way of testing the effectiveness of a wash-aid once you start putting prints through it (other than keeping track of the number of square inches processed), can I make up a washaid/hypo-clear by simply chucking 20 grams of sodium sulphite in to a litre of water, given that it will be chucked at the end of the session? Is it useful to add Sodium Bisulfite in this case?
Using just sodium sulfite may work depending on the hardness of your water supply. If your water is too hard you will get a scum of calcium sulfite on your prints.
The purpose of the sodium bisulfite is to buffer the mixture to a pH at which thiosulfite ion is removed most effectively.
Since the ingredients are fairly cheap I would mix up the HCA formula as a 5X concentrate. Dilute it for use and just toss it at the end of a print session.
I agree with Gerald and in fact, that is what I do. If you have a problem with calcium in your water you can always add some sodium hexametaphosphate to your HCA.
Originally Posted by Gerald Koch
Everything is analog - even digital :D
I do almost exactly this to clear dye from tube-processed sheet film, except I also add a teaspoon of washing soda to that liter of water; alkalizing the gelatin lets the dye (and residual fixer) out faster, and increases the effectiveness of washing as well. It also softens the gelatin somewhat (while it's wet) compared to an acid processed condition, so some care is needed to avoid scratching, but if your film handling is correct, it's not that big a problem.
Sulfite is cheap, washing soda is cheaper. Even on my budget.
Photography has always fascinated me -- as a child, simply for the magic of capturing an image onto glossy paper with a little box, but as an adult because of the unique juxtaposition of science and art -- the physics of optics, the mechanics of the camera, the chemistry of film and developer, alongside the art in seeing, composing, exposing, processing and printing.
D. William Reichner developed a detergent based wash aid in the 1970s that was claimed to be as effective as Orbit Bath. It could be added to the fixer or used as a separate rinse solution.
Distilled water 900 ml
Ammonium lauryl sulfate (15%) 50 ml
Propylene glycol 5 ml
Anti-Foam B 8 ml
Sodium hexametaphosphate 22 g
Distilled water to make 1 l
Dilute 1:1000 for use. (Notice the very large dilution needed.)
The last I saw, all the ingrediants were still available from Photographers' Formulary. The Anti-Foam is needed to prevent a darkroom full of suds.
Ref: Dignan Photographic Newsletter, Vol. 4 No. 1, 1976
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You could also go to an all-alkaline process: developer, water rinse instead of acid stop, alkaline fixer (TF-4 from Formulary, or TF-3 mix at home) and then into the wash. There's no need for wash aid; RC prints are washed in 3-5 min,
Thanks. I was hoping I could just bung a couple of tablespoons of sulphite into a tray and pour 2 litres of water on top... My water is hard so I would probably need the bisulphite too. If going to that level, I may as well make up the full HCA formula as suggested. Ho hum....
Have thought about going all alkaline, but can not find what TF-3 is like in terms of odour. I am not a fan of fixer smell: it gives me a sore throat. I use a low-odour fix at the moment (FX30 from Fotospeed) which works well. TF-4 would have to come from across the Pond and comes as a liquid so is not practical (even if the shippers would accept it) on cost grounds.
Bob, If it's any use to you, that is what I do. ½ film canister of Sod. Sulph. per litre. Mind you, the water is pretty soft around these parts. If you're gannin' alkaline, then you can get alkali fixer (and stop bath) fromwww.monochromephotography.com
Norman is an island.Time and tide wait for Norman.
I mixed up some TF-3 recently. It's great for negatives -- the clearing time when I test most negatives is just a few seconds. (The instructions I've read recommend a 3-minute fixing time.) The recommended fixing time for prints is 1 minute. The problem is that it's got a very strong ammonium odor. This isn't a big issue for film, at least not for me, since the fixer is in closed containers. In an open tray, though, the odor is rather overpowering, at least to my nose. Personally, I plan on sticking with TF-3 for a while for film (I didn't notice the 1:4 dilution when I made mine, so I made more of it than I needed to), but I'll use the Arista Premium Powdered fixer I'd been using before for paper, even though it's got longer fixing times (2-5 minutes are recommended).
Originally Posted by Bob F.
Maybe if it were made up less alkaline it would smell less of ammonia. Maybe the metaborate could be left out altogether. FWIW, in the Darkroom Cookbook, Steve Anchell says that TF-4 (proprietary formula) is less alkaline than TF-3.
Originally Posted by srs5694