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Thread: RA Developers

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    RA Developers

    So,
    After a several year hiatus from analog photography, I'm starting up my darkroom again. I used to use the Kodak RA-4 chemistry one shot kits for home use. Of course, these are no longer available, so I'll have to use a replenishing developer.
    I generally mix smaller package size quantities and store the remaining concentrates in smaller bottles with no air space. This has worked well for me in the past.
    I was planning to use Ektacolor RA Developer Replenisher RT 10L , however I also noticed there Adorama also offers Kodak RA Prime SP Paper Developer Replenisher 10L which has a single concentrate instead of 3. It is more expensive than RA-RT. However, the single concentrate makes for easier mixing.
    So my question is does anyone know how the shelf life of the Prime SP concentrate compares to the RA-RT concentrate?
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    Mike Wilde's Avatar
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    I don't have the answer, but there must be a good reason to store the constituents separately.

    For RA-RT, I pack the CD agent, the B part in full small glass bottles, and thus the 10L kits last at least 3 years for me.

    I make up the replenisher 1l at a time. 50mL A, 23mL B, 50mL C, and replenish the tank in my roller processor with 20mL per 8x10.
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    I buy the 10 liter packages of RA-RT and dilute it straight from the concentrate for use in my Jobo. The formula I use is 250 ml water, 20 ml Part A, 8.9 ml Part B, 20 ml Part C, 12.5 ml Starter, and water to make 500 ml. Kept as the individual parts the shelf life is well over 2 years.

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    I haven't used the Kodak, so don't know for certain that my experience will carry over, but other companies went to a single solution RA dev a number of years ago and I know folks with labs that used those. The ones they used were a thick concentrate that separated out into layers. I assume this is how the manufacturers managed to package it all into one solution and still have good keeping properties.

    We did sometimes mix smaller quantities than the full bottle, but it would be something like 1/2 or 1/4 of the bottle, and a total of a couple gallons or more. I don't think small quantities would have been practical, and even worried a little about these partial amounts we used, but this would have been in replenished systems with about 4 gallon developer tanks, so small errors wouldn't be much of an issue.

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    Hey Mark,
    That's really good to know. Given the single solution is so thick and separates, I'd agree that it probably isn't suitable for mixing small quantities. I think I'll stick with the RA-RT.
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    Quote Originally Posted by pinholer View Post
    I buy the 10 liter packages of RA-RT and dilute it straight from the concentrate for use in my Jobo. The formula I use is 250 ml water, 20 ml Part A, 8.9 ml Part B, 20 ml Part C, 12.5 ml Starter, and water to make 500 ml. Kept as the individual parts the shelf life is well over 2 years.
    You only make up 500ml at a time? Are you using the dev as a one-shot, or do you recover & reuse the developer?
    Emancipate yourselves from mental slavery;None but ourselves can free our minds. - Bob Marley

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    brucemuir's Avatar
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    In my experience the RA-RT stuff lasts a loooong (8months-1yr) time either in concentrate or mixed to 1 litre.
    I've seen others say this here also.

    I reuse the tray solution until it's spent.

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    Yes,
    But Greg & I use a Jobo for processing - not a tray. Since all the chemicals go in and out through the same drum, I'd be a bit concerned with cross-contamination as well as dilution do to water left behind in the drum after the pre-wet step.

    Also, do you have to increase development time as you process prints through your tray, or does the dev time remain pretty consistent until the developer is spent?
    Emancipate yourselves from mental slavery;None but ourselves can free our minds. - Bob Marley

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    Quote Originally Posted by dslater View Post
    You only make up 500ml at a time? Are you using the dev as a one-shot, or do you recover & reuse the developer?
    With 500ml I can process 10 8x10s in the Jobo using the chamistry as a one-shot. That is usually enough for an evenings printing. I have recovered it and continued to use it to process as many as 20 8x10s per 500ml. When I do this I use 2 prewets and develop and bleach fix for 50 sec plus a drain time of 10 seconds each. My stop is 1.5 oz of glacial acetic acid per gallon and I don't try to extend that. Because the solutions are becoming more exhausted, I use 200ml for the developer and bleach fix instead of the usual 100ml. The developer starts out the usual light beige color and becomes a dark blue as it is reused. After 20 8x10s it is almost black. That is where I stopped although I could probably go further since there was no change in either color balance or density.

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    It's fairly consistent.
    I use a timer and the time depends on temp (room temp in trays) although I haven't found it all that critical.

    With a JOBO it may exhaust quicker but I was mostly talking about keeping properties of the concentrate and mixed solutions.

    I'll mix 1litre batches (sometimes have 2-3 on hand) so I have some fresh stuff if the 1st bottle goes while I'm printing. I store in FULL pet bottles and it amazes me how long it keeps.

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