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  1. #1

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    Platinum/Palladium exposure issues

    I just got back to alternative printing after a bit of a hiatus and am starting out with the Na2 method. I was printing yesterday for the first time with this technique and ran into a few problems.

    My primary problem is very long exposure times and lack of Dmax. I am printing on COT320 (after abandoning a very uncooperative batch of Arches Platine). I am using the Pd and ferric oxalate in equal proportions with a couple of drops of Na2 5% per 8x10 for contrast control and potassium oxalate as a developer. I even double coated, but this did not seem to help much. I am brush coating with a Richeson brush. Humidity levels and temperatures are within acceptable levels for this time of year (I ran a heater and humidifier in the room). All my chemicals are fresh from B&S this week. I am using a bank of fluorescent tubes at about 6 inches (I am not exactly sure what kind, but they were marketed as under counter grow lights) and my exposure times were over an hour, and even at these levels, I am not quite getting two of the least dense steps on the step tablet to merge as black. I would blame the light source, but last year I did lots of kallitypes and they worked fine with exposures of about 30 minutes -- and this was with pyro developed negatives. The neg is sandwiched under the same glass I have used in the past and it is not UV blocking (I thought of that). Currently my negs are developed in D76 and I am pretty sure that they are well tailored for the process. (Of course, the step tablet suggests that the problem is independent of the negative.)

    I fully expected that with the Na2 process and non-pyro negs my exposures would be in the 15 minute range based on my kallitype experience with pyro negs. Is palladium that much slower than kallitype? It does not seem that it should be.

    Any thoughts as to what might be going on? Would low relative humidity cause these issues? I suspect that even with a humidifier my basement is a little dry. Though when I was trying to get the Platine to work I brushed it with a 10% oxalic acid bath and the paper was nicely humidified when coated and with this arrangement I was still getting hour plus exposures, so I don't think that is the issue. But if it is the lights, why would they work well for one process and not another. Very confused....

    Any suggestions would be much appreciated.

    Thanks,
    Paul

  2. #2
    billschwab's Avatar
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    First suggestion from me would be to get BLB bulbs. Grow lights never worked for me. With the BLBs I get about 8-9 minute exposures. IMO, 30 minutes - 1 hour exposures are crazy, even if they work! Also... 2 drops of NA2 per 8x10 seems like a lot.

  3. #3
    TheFlyingCamera's Avatar
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    I don't know what kind of humidity levels you have in your printing environment, but it could be a factor-
    the same neg that takes me 6.5 minutes in the summer with full humidity can take 20-40 mins in the coldest driest months of winter. If that is not the issue, I'd go with Bill's suggestion of changing your bulbs. Home Depot sells blacklight fixtures and appropriate replacement bulbs that work just fine, and are quite cheap.

  4. #4
    Jim Noel's Avatar
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    Change your bulbs, and get them closer. There is no need to have them 6 inches from the print. There was study published a few years ago in the Post Factory Journal which showed no banding when alternate tubes were blacked out and the coated paper laid directly on the tubes. Mine are about 3/4" above the printing frame and I have never had any banding.
    [FONT=Comic Sans MS]Films NOT Dead - Just getting fixed![/FONT]

  5. #5

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    Thanks for the responses. It looks as though it might be time for me to reconsider my bulbs. I will see what I can find. I noticed that Home Depot also now sells a 400 watt HID self balasted lamp, which might be good for 8x10 if placed in a reflector. I might try something like that as an inexpensive temporary solution while I work on building a decent UV unit.

  6. #6
    nick mulder's Avatar
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    I'm using 8 BLB bulbs and my exposures are about 70secs for NA2 in 8x10

    30mins ? whoah!
    Cleared the bowel problem, working on the consonants...

  7. #7

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    I just got back from Home Depot and I managed to find the BLB units that The Flying Camera mentioned. I had searched for these before and not been able to find them. I will set up a unit with these tomorrow. I bought 5, which should be enough for 8x10. I will report my results. Thanks.

  8. #8

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    I set the BLB units up and printed with them for the first time yesterday and they make a huge difference. My printing times are now in the 6 minute range with the paper about 6 inches from the lights! I have other obstacles to overcome in my printing skills, but one weak point has been eliminated.

  9. #9
    nick mulder's Avatar
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    I have 8 Sylvania F20W/350BL bulbs (not BLB as previously stated) at around 3 inches - 6mins is pretty good, much more productive than 30min
    Cleared the bowel problem, working on the consonants...

  10. #10
    billschwab's Avatar
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    Quote Originally Posted by nick mulder View Post
    I have 8 Sylvania F20W/350BL bulbs..
    Thanks for the correction Nick. Please forgive my earlier post as I mistakenly said BLB. I meant BL as those are the ones I use. I know that BLB's will work as well (obviously as they are working for Paul), but have heard longer exposures were the result. Unlike BLB's or "black lights", BL's appear white when unlit and have an eerie bluish glow when lit.

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