RA4 without stop bath

Discussion in 'Color: Film, Paper, and Chemistry' started by newcan1, Feb 24, 2013.

  1. newcan1

    newcan1 Subscriber

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    I process RA4 paper in a drum, and I'm trying to speed the process up a bit - I can't afford a roller transport processor! I currently mix my own developer but use Kodak bleach-fix. I also use an acetic acid stop bath in between.

    Is it possible to eliminate the stop bath without problems? What can I anticipate? It would save a bit of time to go straight from developer to Blix.
     
  2. markbarendt

    markbarendt Subscriber

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    It works fine but I have found that using stop and fix makes my blix last longer and I have a lot fewer failures. I also use a pre rinse before the developer.

    What temp are you using?
     
  3. newcan1

    newcan1 Subscriber

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    Hi Mark - it's a bit of a long story. I use 98 deg F or thereabouts, but right now I'm using a slightly modified developer (10mg/L benzotriazole and 3ml/L hydrogen peroxide). This is because I have 1,000 sheets of Fuji Crystal Archive C 8x10 of dubious prior storage that had a bit of yellowish base fog, and the modifications remove the base fog and punch up the contrast a bit with outstanding results. Anyway, I am finding that developing for 2mins instead of one gives best results with these mods and this paper. From what you say, it probably isn't worth removing the stop.

    I also pre-rinse to bring the drum up to temp.
     
  4. markbarendt

    markbarendt Subscriber

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    I'd definately keep the stop. That's only 30 seconds fill, run, and dump for me.
     
  5. Rudeofus

    Rudeofus Subscriber

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    Using a stop alone might be a lengthy procedure with no immediately visible purpose, but using a stop&fix as suggested by Mark will improve BLIX life. Such a stop&fix is dirt cheap and easily mixed from 200 g/l Sodium Thiosulfate, 50 g/l Ammonium Chloride and 20-50 g/l Sodium Metabisulfite (Agfa 304 recipe with optional extra Sodium Metabisulfite). Remember that BLIX rarely runs out of bleaching ability but quickly exhausts its fixer component, so taking away Silver Halide before BLIXing will help a lot.
     
  6. newcan1

    newcan1 Subscriber

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    Interesting idea, stop & fix - would the 200g be for the crystalline version of sodium thiosulfate?
     
  7. Rudeofus

    Rudeofus Subscriber

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    AFAIK the Agfa 304 recipe uses 200 g/l of the crystalline version (Na2S2O3 * 5H2O).
     
  8. newcan1

    newcan1 Subscriber

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    What purpose does the ammonium chloride perform in stop & fix?
     
  9. polyglot

    polyglot Member

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    It substitutes for the sodium with the thiosulfate; it's basically a way of getting something a bit like rapid fixer (ammonium thiosulfate) if you only have access to sodium thiosulfate.

    As to the original question, the Kodak docs do say that the pre-blix stop+wash steps are optional for RA4 and that you run the risk of magenta streaking if there is any developer carry-over into the blix bath; it can be avoided with careful squeegeeing in a roller processor but is practically inevitable with a drum. Developer will also raise the blix pH and reduce its effectiveness.

    A stop+fix step will certainly help your blix out, but given its price ($2.50/L) and replenishment rate of 10mL/sheet (2.5c!), I really don't think it's worth spending any extra to make a special fixing stop bath. I'm pretty sure that my blix (or I!) will die of old age before it runs out of its 2000 sheet capacity...
     
    Last edited by a moderator: Feb 24, 2013
  10. Photo Engineer

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    Don't use a fix after the stop. Use the blix. The life will be longer and the results will be more constant, from print to print.

    PE
     
  11. Rudeofus

    Rudeofus Subscriber

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    I never had problems with consistency from print to print. And I really don't get how I could decrease BLIX life if I take out 50% of the Silver before.

    polyglot: If you get RA4 BLIX for $2.50 per liter of working solution then there is certainly no point in preserving it. If, on the other hand, you spend $68 on a 5 liter RA4 kit, you tend to squeeze out every droplet of its chemistry and a cheap stop/fix bath is one step in that direction.

    PS: I use a 30 second water wash step after my Agfa 304 stop/fix which prevents chemistry carryover from my stop/fix into the BLIX.
     
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  12. polyglot

    polyglot Member

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    I got my 4x5L Kodak kits from Ag Photo in the UK; even with shipping it's going to be better than half the Freestyle price. Split the packs with a friend if necessary!
     
  13. Photo Engineer

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    Rudi;

    The OP wanted to speed up the process time. Using a separate fix and then a blix would increase process time. As for using a plain fix after development, (if that were the case) then the fix capacity would diminish by carryover.

    A sequence of Dev, Stop, rinse?, Fix, rinse?, blix would be needed and that is just too long but it would increase blix life.

    PE
     
  14. Rudeofus

    Rudeofus Subscriber

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    I would assume that CD and fix alone would not work in RA4 since the developed Silver would remain in the paper ...
    My current process sequence is CD, stop/fix, rinse, BLIX, rinse, wash. Final wash is done in a water basin, so the whole Jobo time is about 8 minutes. That's not too long IMHO and compares well to time spent on thinking about filtration/time changes, other preparation steps and exposure.

    Polyglot, these prices for Kodak RA4 are almost too good to be true! Look at the sorry Tetenal kit on the same page, it's four times as expensive per liter working solution. Unbelievable ... :confused: Is there a difference in capacity per liter of working solution or something?
     
  15. Photo Engineer

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    My total process through blix is 3 minutes at 100F and about 5' at 68F. The former in a Jobo and the latter in trays. The former also must have added to it a 30" 100F prewet.

    PE
     
  16. nworth

    nworth Subscriber

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    Kodak says you can omit the stop bath in RA-4 processing, but I have found that to be a very unwise procedure. Keep the stop bath. It only takes a few seconds. When I omitted it, I sometimes got all sorts of stains and blotches, which wasted both time and materials.
     
  17. Rudeofus

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    My process time is longer because I process at 30°C and that I use very conservative times for BLIX (2+ minutes).

    Here is my time regime:
    1. CD for 1:45
    2. Stop/Fix for 1:15
    3. water rinse for 0:30
    4. BLIX for 2:00
    5. rinse for 0:30
    6. rinse for 0:30
    7. rinse for 0:30

    The Stop/Fix takes one minute longer than a Stop alone, but I assume that within 1:15 even a Sodium Thiosulfate/Ammonium Chloride based fixer removes most Silver Halides left after the CD step, thereby leaving only the developed Silver for the BLIX. The BLIX time is very conservative and even Tetenal's instructions call for only 1:00. The three rinses at the end not only ensure that I won't touch nasty chems with my bare hands when I open the tank, it also cleans the tubing within the Jobo so the next tank doesn't get left over BLIX with its CD. The Jobo is ready to go for the next tank!

    With these processing steps I have seen color changes towards blue after processing many sheets of paper, and I would attribute these to exhausted CD. These color changes could be corrected through filtration but as they got worse with more sheets processed it turned into a futile catchup game. I never got poor Dmin from exhausted BLIX, even in those sheets with extra blue cast.
     
  18. polyglot

    polyglot Member

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    I don't know the capacity of the Tetenal - I looked at the prices and went "duh, I know which I'm getting". The Kodak ones are packaged as 4 sets of bottles so you can make up 5L and keep the rest as concentrate (or sell them!) without opening. If anyone in Australia wants a Kodak 5L RA4 kit for $40, PM me as I still have one spare.

    The Kodak requires about 10mL of replenishment per 8x10", so all up cost (with shipping) in AU is 8c/sheet. Certainly it's a good price, but it's not like the chemistry is inherently expensive (PtCl2!) or hard to make. And the shop is for real; they're an APUG advertiser and I've bought that very set of kits from them myself, as well as the Fuji C41 and E6 offerings.

    PE: I think the stop/fix suggestion above was intended as replacement for a stop bath, not something to do between a stop and a blix. Since fixer is pretty acidic, it will act as stop and have the neat side effect of reducing silver load on the blix. Due to the high cost of (presumably B&W rapid) fixer vs acetic acid and the low price of RA4 blix as stated above, I don't see much point though.