Exactly 6,66 g/l. That means 0,666%, expressed as g of carbonate in 1000 ml of solution.
I'm just back from Russia, and catching up on things. I'm glad to see some of you having success with this developer.
Dan - Thank you for the detailed review. I assume the sodium sulfite is an error and meant to be sodium carbonate That OA used with intermittent agitation is sharper than Pyrocat HD used with semi-stand agitation is jut what I have found, as well, and you're also right to expect even sharper results with decreased agitation frequency.
Dominik - when I was testing OA, I tested carbonate concentration ranging from about 3g/ liter of working solution up to about 20g/ liter, and everything in this range is useful. The 666 solution resulted from diluting a more concentrated stock solution, and is a kind of sweet spot between 5g/ liter and 7.5g/ liter -- lower concentrations of carbonate begin to impact film speed, and higher concentrations tend to increase contrast and grain, but nothing was signed in blood, so I think my immortal soul remains free and clear.
gth- I don't know the shelf life of catechol powder, but I suspect it's good for at least several years properly stored, as mine is that old and still working fine. I haven't tested OA for developing capacity, but I know 1ml of concentrate will safely develop 1 roll of film, or equivalent.
Matt - thanks for the info on processing X-ray and IR films. Your examples on Flickr look great!
I continue to have good results with this developer, until I apparently pushed my luck a bit too far. I began developing FP4+ for 9 minutes at 21c, agitating the first minute then every 2 minutes thereafter as recommended by Jay. Being a minimal agitation guy, I began reducing agitation to 2, then a single period after initial. Things went nicely until yesterday, when some negatives with a clear sky were mottled and uneven in that area. It seems that I have read that stand or semi stand can be unpredictable, which seems to be the case here. In a subsequent session I added back an additional agitation period with no apparent adverse impact on sharpness.
A couple of questions for Jay if he happens to stop in:
1. I use a Yankee tank that can hold up to 12 4x5 sheets, although unless I have been on a shooting trip I seldom process more than 3 or 4 sheets at once. The tank holds 1625 ml, which works out to 3.25 ml of the A solution for 1+500. Would this amount of developer be sufficient for up to 12 sheets if the need arose?
2. When I used Pyrocat I would sometimes re use the developer on another batch of film requiring a different development time, with the developer sitting in a graduate for only a few minutes before being re used. Can this be done with O.A.? Or is it pretty much done after one use? Cost is obviously not a factor, but I have adopted the philosophy of not needlessly putting chemicals down the drain since moving into a house with a septic system.
I'm glad you're getting good results. Finding a sweet spot for agitation is an important part of getting the most out of this developer, and as you found, at frequencies high enough to prevent defects, there is little negative impact on sharpness.
On capacity- the 1:500 dilution is standard, and used to develop 35mm film in 300ml of solution, with 0.3ml of stock. Since 4ea 4x5 sheets = 1ea 36 exp 35mm film, 1ml of stock will develop at least 12 sheets of 4x5 film, so 3.25ml is more than safe.
I do not recommend re-using OA -- it might work, but it's just not worth risking. And I wouldn't worry about adding it to your septic tank, either -- catechol, carbonates and metabisulfites are all found in things we eat and drink, and, consequently, in our urine, in far greater amounts than you're likely to add by dumping this very dilute developer.
How about some example pics?
Thanks for posting an example, Dan. It looks great! There's a very nice contrast between the sharp edged rocks and velvety water. Nice image color, too. I tend to prefer warm images. I look forward to seeing your churches!
Thanks for your reply!! So, if 0.6ml of stock is needed for one roll of 35mm film and to develop four sheets of 4x5 film. Then it seems that at least 2.4ml would be needed for twelve sheets of 4x5. It's important because I wish to have an adequate volume of OA for 5x7 and 5x12 film.