Reusing C41 Chemicals

Berri · Jun 5, 2018

Mr Bill said:
I would also say that the quality of the final images is really the final arbiter; using control strips and thermometers and timers, etc., is just a way to give you some control over the process in an attempt to meet the manufacturer's specifications.

exactly. As I said I take a lot of care when processing my negtives and I can tell that my results are good because I get to print them easly and with impressive results.

Berri · Jun 5, 2018

RPC said:
If one lacks a densitometer then the next best think would be to shoot (exposed properly) and print a gray scale. If it can be color balanced so the gray patches match or are very close to the original, then crossover can be disregarded. A noticeable shift in color along the scale would indicate some. Of course this depends on your print process being accurate.

this is more or less what I do. I take a shot of a grey card at the beginning of the film (including a kodak color checker) in proper light conditions and I also take a shot of a grey card for situations where light temperature is less than adequate (to help me balance the photos taken in the same light conditions) I never had any crossover, the only time I had severe colour cross over was when I Pushed portra 400 to 3200, it was not possible to balance it properly and the colours were preatty bad.

RPC · Jun 6, 2018

You say gray card, I said gray scale. The various patches of gray of a gray scale, with constantly changing densities are helpful in seeing any unwanted color shifts with density changes, due to nonparallel R,G, & B charcteracteristic curves, which is what crossover is.

Berri · Jun 6, 2018

RPC said:
You say gray card

I said more or less and not just a grey card but a colour checker too, which has a grey scale in, anyway you miss the point. At that stage any colour shift that may have occurred will be affecting all your frames and photographes therefore ther is no need to check it with a densitometer for two reasons reason one, you do one shot so there is nothing to be adjusted in the process. Reason two, you print your negatives optically so either they print fine or they don't. As I said before it is totally usless to check that on a film where you took photos you presumably you care about.

RPC · Jun 6, 2018

I think you miss the point. I check each roll to see if there is some problem occurring with the process. Normally there isn't, but if one should suddenly occur, I can readily detect it with the gray scale. Even with one-shot, although normally not a problem, factors such as temperature, mixing errors, contamination, etc. can affect the process. You can't fix what has already been affected but you can readily see that it has been affected, and try to diagnose and fix the problem with more testing before proceeding with important stuff. If I was re-using developer and suddenly at the nth roll I start to see crossover, I can stop re-using it, or perform more tests to determine if I have reached the limit and prevent any further problems due to re-use. Basic quality control.

Berri · Jun 7, 2018

RPC said:
I think you miss the point. I check each roll to see if there is some problem occurring with the process. Normally there isn't, but if one should suddenly occur, I can readily detect it with the gray scale. Even with one-shot, although normally not a problem, factors such as temperature, mixing errors, contamination, etc. can affect the process. You can't fix what has already been affected but you can readily see that it has been affected, and try to diagnose and fix the problem with more testing before proceeding with important stuff. If I was re-using developer and suddenly at the nth roll I start to see crossover, I can stop re-using it, or perform more tests to determine if I have reached the limit and prevent any further problems due to re-use. Basic quality control.

ok, but why don't you use control strips then? If you find yourself in a problematic situation you would judge it on a strip, not on potentially good photographs ruined by poor development or other issues, do you see what I mean? If you were re-using developer AND using control strips at the 9th roll you would find out that you may have to increase the developing time by 10% or adjust the replanishing rate or check the temperature or whatever, but no photographs would have been damaged, what I trey to say is that you are able to perform all sorts of test with your equipment but you just do one shot, where it is obvious that no issues would occour...there is no sense in that! By adding controll strips prior to the process of important material would make you save money and consistency in result would be just as fine

RPC · Jun 7, 2018

Commercial control strips are expensive, and making my own a bit time consuming and I can not justify the cost or effort considering, as I said, I rarely have a problem. When I do, it is usually mInor and hints that something is not quite right and I have been able to fix the problem before anything else is affected or the problem gets worse. My way of doing it has worked well enough; it is a good way to give me some protection without excessive cost or effort. However, if I re-used my chemistry, control strips would be something I might consider.

jbrubaker · Jun 7, 2018

RPC said:
Commercial control strips are expensive, and making my own a bit time consuming and I can not justify the cost or effort considering, as I said, I rarely have a problem. When I do, it is usually monor and hints that something is not quite right and I have been able to fix the problem before anything else is affected or the problem gets worse. My way of doing it has worked well enough; it is a good way to give me some protection without excessive cost or effort. However, if I re-used my chemistry, control strips would be something I might consider.

Yes control strips are expensive and require a densitometer to interpret. There is not much you can determine visually from a C-41 control strip.

Berri · Jun 7, 2018

jbrubaker said:
Yes control strips are expensive and require a densitometer to interpret. There is not much you can determine visually from a C-41 control strip.

RPC has a densitometer

Berri · Jun 7, 2018

RPC said:
Commercial control strips are expensive, and making my own a bit time consuming and I can not justify the cost or effort considering, as I said, I rarely have a problem. When I do, it is usually monor and hints that something is not quite right and I have been able to fix the problem before anything else is affected or the problem gets worse. My way of doing it has worked well enough; it is a good way to give me some protection without excessive cost or effort. However, if I re-used my chemistry, control strips would be something I might consider.

that is fair enough. I get satisfactory results by reusing my chemicals and I would only consider using replenishing and test strips if I were to process for other people as a service. I am really happy with my workflow and with the prints I get. I use both bellini C41 and RA4 and consistency is very good from 1st roll to the last

Reusing C41 Chemicals

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