I have recently started to develope my own colour film using Paterson Photocolor II and a standard developing tank. The results have been fairly good.
I have now aquired a Jobo Duolab which uses a rotating drum and only half the developer. What I would like to know is if there is any adjustment on times I should make to allow for the continuous agitation and smaller amount of chemicals.
I asked this question in the B/W forum and someone kindly replied and told me that with continuous agitation times should be reduced by 10-15%. I just wondered if the same applies to colour developing.
My second question concerns the shelf life of colour developer. I bought two litres of developer from a local photographic supplier and when I got them home they had been opened and used; one was quite dark and looked as if it had been opened for some time. The supplier has refunded my money but I still have the developers and to be honest one bottle seems okay but when I tried the second second bottle the film seemed extreemy underdeveloped Which I put down to the age of the opened developer.
All this is not to try to get something for nothing but to try and increase my knowledge of home processing by experimentation. All answers on the above would be very gratefully received.
"I asked this question in the B/W forum and someone kindly replied and told me that with continuous agitation times should be reduced by 10-15%. I just wondered if the same applies to colour developing."
This may be true with B&W chems, but not colour. Your times should be whatever Jobo recommends or 3'15" .
I have been told that mixed chems, exposed to the air will last 1-2weeks on the outside and that mixed chems with an inert gass blanket (as in nitrogen) will last a month (which is what I do with my Wing-Lynch). I would do further research before trusting my opinion.
I have been processing C41 and E6 for many years, and am still using Nikkor tanks and reels in a water bath. To determine developer life and activity, I suggest that you shoot a roll of the MacBeth color chart using your normal film and camera. Don't bracket exposures. Shoot a set in full sunlight at the proper exposure. Fish out the leader of the roll and store it in the fridge in a capped film can. Use this for your test sequences. Cut off and develop a few frames to determine your developer's activity.
In this regard, a calibrated film scanner can be of benefit to determine if you are getting results consistent with fresh chemistry. It's certainly not as good as densitometry, but gives you a guideline. Of course visual inspection and comparison with your "standard" MacBeth negative does the same. You should count on around two weeks for tightly sealed, full bottles of partially used chemistry. Note that the lifetime for the blix and stabilizer is far greater, typically a month or more. It's the developer that oxidizes and fails first.
M. T. Sandford
I would NOT deviate from the published times: I use Tetenal in the JOBO, and Color Developer for 3' 15" at 38C seems to be standard. Bleach-Fix can vary from 4' 00" to 8' 00". I'd stay with the manufacturer's recommendations.
From memory... Photocolor Color Developer was a mixture of three solutions; "A", "B" and "C". "B" was the problem: originally, it is "light straw" in color - it will rapidly darken, and when there is an appreciable color change it is *SHOT*.
Strange ... I've had that happen to me ... I purchased a Photocolor C41 "Kit" and when I got it home found that it had been opened, the chemicals half used - and solution "B" was BLACK - and "chunky". I brought it back ... more or less screaming. Their attitude was ... "Oh yeah, That happens. Here is a new kit."
No emotion whatever. That cost me a 70 mile round trip into the heart of Boston, and four days of delay ... and all they could say was, "Oh yeah .. that happens..."
Shelf life is a problem with color chemistry. The only dry chemicals I can find on this side of the pond are Tetenal's C41 "Press Kit" - at about twice the cost of their regular wet chemicals. All in all, this may be the most cost effective way to go.