What stop bath do you use?greenspun.com : LUSENET : B&W Photo - Film & Processing : One Thread
I just use a little acetic acid (24%) in the water to make stop baths. I don't bother to messure...
Do you buy your stop bath, use glacial acetic adic or maybe citric acid?
Here are two Agfa recipes:
Stop Bath for paper, Agfa 200:
Glacial Acetic Acid (99%) - 20.0 ml Cold water to make - 1.0 liter
Stop Bath for films, Agfa 201:
Potassium Metabisulfite - 40.0 grams Cold water to make - 1.0 liter
Potassium Metabisulfite? This must be an expensive stop bath to use, and why this chemical?
-- Patric (email@example.com), April 06, 2001
I start with glacial acetic acid because it is cheap. I mix it down to a 28% solution by adding 3 parts acid to 8 parts water. Then I add 1.5 oz of 28% acetic acid to a quart of water (or 45ml to a liter) for my working solution.
I no longer use an acid stop bath for most films. Instead, I rinse in tap water--four complete changes of water over a minute to a minute and a half. If I do decide for some reason to use an acid stop bath, I always give the film a water rinse first.
In regard to your question about the metabisulfite stop bath, the chemical, though essentially a salt, has a slightly acidic reaction, and so makes a good mild stop bath. It is probably less likely to cause pin holes in negative emulsions if you don't use a water rinse.
-- Ed Buffaloe (firstname.lastname@example.org), April 06, 2001.
Patric, Metabisulfite and acetic acid can both smell too much within the walls of darkroom, mainly on trays. Citric acid can also be used, at 10/20%, making your life somewhat more comfortable in the dark. All those chemicals are inexpensive and not so necessary with films, as they usually don't carry over much developer. Fiber paper, in the opposite side, can spoil fixer much faster if a stop bath doesn't come for help. Wich acid soap does the trick, usually doesn't make much difference. Good work.
-- Cesar Barreto (email@example.com), April 06, 2001.
For prints I use water.
-- Christian Harkness (firstname.lastname@example.org), April 07, 2001.
Ilford recommends that you don't use a stop bath because of the possibility of pin holes.
-- Joe Miller (email@example.com), April 07, 2001.
I have had problems with pinholes on Efke films, but I thought that was because of the agitation. Efke film has a very thin layer of emulsion. Hmmmmm, maybe I should try a plain water stop bath in the future with these films?
-- Patric (firstname.lastname@example.org), April 07, 2001.
Hey, that should have been 'for film I use water'! Duhhhhhhhh
-- Christian Harkness (email@example.com), April 08, 2001.
For those who use water, how many changes? Since I don't have running water in my darkroom, is there any disadvantage to using just one 1 minute water bath with agitation (other than killing the fix more quickly)?
-- Raja A. Adal (firstname.lastname@example.org), April 08, 2001.
I use Kodak Indicator Stop Bath at 1/2 the recommended dilution (approximately 7ml per liter)& discard after use. No pinhole problems on film and it lasts an entire printing session.
-- Robert Orofino (email@example.com), April 08, 2001.
Potassium Metabisulphite is a very cheap chemical. It's widely used as a preservative and cleaner in winemaking, brewing and other food preparation, and is available in convenient tablet form. It forms Sulphurous acid in solution, the same acid as in Fixing baths, hence the same pungent smell. This also makes it totally compatible with normal acid fixing baths
Pinholing is caused by carryover from the developer outgassing within the emulsion. The main culprits are developers with a high carbonate content, and higher than normal processing temperatures. The carbonate breaks down to give off carbon dioxide in any acid solution.
The 'cure' would be to use a two bath stop, the first plain water, and the second a weak acid bath to prolong the life of the fixer. This kind of defeats the secondary purpose of the stop bath, which is to rapidly arrest the development.
-- Pete Andrews (firstname.lastname@example.org), April 09, 2001.
I am not sure on how many changes of water, if you don't have running water. However I believe as long as you are consistent in what you do, you will be ok. For starters I would try a couple of changes of water and letting it sit for a couple of minutes at least. Be sure you monitor your fixer.
-- Christian Harkness (email@example.com), April 09, 2001.
I have used Kodak's indicator but didn't like the smell all that much, went to Sprint's Stop which is vanilla scented and that was great for awhile but usually now it's just citric acid and change often. Cheers, Scott
-- Scott Walton (firstname.lastname@example.org), April 10, 2001.
changes of water? every 30-40 secs of continous and strong agitation, during 2 mins.
-- Celcio (email@example.com), April 16, 2001.