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  1. #1
    dpurdy's Avatar
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    Tween 20 questions

    I did quite a lot of research here in APUG but still have some Tween questions. I tried it out yesterday and it seemed to be very helpful in smoothing the tonalities but one of the three prints ended up (after washing and drying) with small shiney spots that I had to gingerly pick off with needle.

    Questions;
    how many people are actually using Tween 20?
    always? sometimes?

    If a little is good is a lot better? Is the affect variable with using less per print. I was using 6 drops 10% solution per 10x10 print.

    Is the same affect achieved by just letting a fresh coated paper air dry?

    re my research, does everyone agree that tween and Arche's Platine don't mix? Any idea why? What is the negative affect?

    Other than the one print with glossy spots on Crane's 90lb it seemed all good to me. Is there a down side once I get over beginner's luck?

    Is one source of tween better than another. I was using some aged Bostick and Sullivan tween 20 10%.

    Do you think my glossy spots on the one print are from something other than the Tween since I didn't get it on two other prints?

    I don't see any loss of dmax on the Crane's paper in comparison.. though maybe a loss of contrast. Re my research I saw some complaint of dmax loss. Is that only on certain papers?

    If you can answer some of these questions or give an educated opinion I would greatly appreciate it.
    Thanks
    Dennis Purdy

  2. #2

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    I use Tween 20 when sensitizing for Kallitypes on Arches Platine & COT320 (Christopher James says for latter paper highly recommended). Use only 1-2 drops per print. I would think that too much would lead to sensitizer trails. What you're experiencing sounds like bubbles on paper which should be eliminated while brushing.
    van Huyck Photo
    "Progress is only a direction, and it's often the wrong direction"

  3. #3
    nze
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    I use it @ 0.5% with platinum palladium, just to smooth the sensitizer. I could use stornger but it depends on paper and 0.5 work on any paper So I keep it . With ruscombe I use a stronger dilution 5% ( 1 drop / 8X10 print)
    Chris Nze
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  4. #4

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    hi dennis --

    Questions;
    how many people are actually using Tween 20?
    always? sometimes?
    -- i used to use it when coating with a glass rod to aid coating, but stopped using it when i went back to brush coating because i noticed less dmax with tween vs without .... it does smooth out tonalities, esp. the higher tones, but you might try humidifying the paper too (or as an alternative) to smooth out tones (i take it you are using the a+b method?)

    If a little is good is a lot better? Is the affect variable with using less per print. I was using 6 drops 10% solution per 10x10 print.
    --six drops is a lot! .... i never used more than one drop per 8x10 print ...

    re my research, does everyone agree that tween and Arche's Platine don't mix? Any idea why? What is the negative affect?
    -- my experience is that tween dulls the dmax most significantly on arches platine, but also on cott320 and artistico somewhat

    Other than the one print with glossy spots on Crane's 90lb it seemed all good to me. Is there a down side once I get over beginner's luck?
    --other than slight loss of dmax, none i know of

    Do you think my glossy spots on the one print are from something other than the Tween since I didn't get it on two other prints?
    --don't know what would cause glossy spots or specs

    well, you now know everything i know ..... good luck
    rich
    (ps -- do you still keep in touch with todd parker? i used to shoot with him but he moved up to sw washington a few years back and i lost track -- or did i already ask you this question on one of your earlier posts!??)

  5. #5
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    Hi Rich, you did ask that before and unfortunately I have lost contact with him as well. Thanks for all the answers. I don't actually use part B, I use Hydrogen Peroxide and the other type of platinum... whatdoyoucallit N something. I am brain dead. the instructions that came with the bottle of tween or that I got somewhere suggested 1 drop of 50% tween per 8x10. I have 10% so I upped it to 6 drops per 10x10 but I think I will try it with less. Though I really can't see any loss of dmax just a loss of contrast.

  6. #6
    nze
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    With Cot and Arche paper I use only a 0.5% drop. As Rich wrote TO high concentration lead to tranform the paper in sponge.
    Some paper like the Buxton can supprt more concentrated tween solution.
    Concentration of the tween really depend on the paper.
    Wejust want the emeulsion to be on the top layer of paper nad if there is too much tween it goes deeper in the paper and result in less contrasty and less defined print.
    At last take care with sensitizer conatingin gold, the tween gold mix can transform some paper in sponge if the tween is too concentrated.

    You mean NA2
    Chris Nze
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  7. #7
    dpurdy's Avatar
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    Thanks Christian. It just seems so little is necessary for a large affect but that is a good thing. I don't ever use gold. In the past I only got unpleasant pink colors from it. Yes Na2.
    Dennis

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    so dennis, how are you using your na2? diluted or straight? with eyedropper or those little pipette things? how much na2 do you use with your pd+f.o. for a 'normal' negative? i experimented with na2 diluted a few months back but with mixed results, but i want to try again

    rich

  9. #9
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    Hi Rich. I use it with pure palladium as otherwise I guess it doesn't work and I find that it has the affect of cooling the print color a little. I use it as supplied by Bostick and Sullivan though I understand that lots of people.. maybe most actually dilute it. I use an eyedropper just like everything else and find that it generally only takes 1 or 2 drops per 8x10. If I get up to 3 or over drops I start mixing in hydrogen peroxide instead. I really haven't done scientific testing to see exactly how all this stuff works individually or in concert with other agents. I don't know for example what is the affect of using some part B with potas chlorate and some hydrogen peroxide and some Na2 and then putting a dash of postas dichromate in the developer. Is combining them a way of boosting contrast without getting so much grain? I don't know. And I don't know why using Platinum in the mix increases the mottling and grain problems either.
    Probably not very helpful, eh?
    Dennis

  10. #10

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    thanks for the feedback about the na2, dennis ..... sorry for the delay in getting back, but i've been out to mt rainier looking for pictures ...... i think i'll use one of the rainier negs to try the na2 straight next time the way you did, adding one drop for a normal contrast neg for starters..... regarding your comment about combining all those different contrast control methods at one time -- i'm no scientist but i don't think that's a good idea -- for example, adding part b in the mix with na2 would be counterproductive ..... but i admit that my experience has been limited to using pd and the a+b method for a few years in the 90s, then about 7 or 8 years ago i started adding about 20-40% platinum to the palladium, initially to eliminate solarization in the shadows, and have continued with that ever since .... the platinum addition also yields deeper blacks, increased contrast, a cooler color and (not necessarily a plus) longer print exposure times ..... the a+b method works great for me most of the time, but if i have to start adding lots more B than A to increase the contrast of a flatter neg with large, smooth tonal areas (like sky, water, etc), then it likely will look grainy (i think it's what arentz calls floculation) on certain papers, esp. arches and cott320 ..... sometimes humidifying the paper helps, and on some papers tween helped (notably on the old crane's bright white), but as i mentioned earlier, tween also tended to decrease dmax, esp on arches but also on cranes ..... since i like both arches and esp. cott320 papers (and crane's is no longer reliable), i decided to experiment with na2 ...... despite some failures due to not using fresh pot.ox. developer (unpolluted by previous pt/pd developing) my first experiments with na2 did get me a couple of really smooth prints (on fabrico artistico) with an older, thin neg of piers in the columbia (in foggy light to boot) that i always had trouble printing before ..... i had less luck with na2 on arches and cott, but i'm ready to try again ..... after all, it's only money
    rich
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