Streaking with Richeson 9010 Magic Brush

Discussion in 'Alternative Processes' started by donbga, Dec 21, 2004.

  1. donbga

    donbga Member

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    Hi Everyone,

    I'm occasionally getting streaking when coating with a magic brush and don't understand why. Does anyone have any tips to share?

    Thanks,

    Don Bryant
     
  2. Jorge

    Jorge Inactive

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    The brush is either too dry or too wet. I have had this happen to me in both instances. Specially when the brush is too dry and the climate is dry too. Happen to me with 3 12x20...you probably heard the cussing... :smile:
     
  3. sanking

    sanking Member

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    Don,

    Has this been going on for very long? If it is of recent origin I suspect that the unusually cold weather and low humidity we are experiencing in the southeast at this time may have something to do with the streaking.

    I rarely experience streaking when coating with the Richeson but it is hard to describe the technique of coating. First, make sure that you use enough solution to go over the print from side to side, up and down and on the diagonal before the sensitizer starts to dry. And, use very light brush strokes as you complete the coating. The few times that I have seen streakiing the most probable causes were, 1) beginning to coat with an insufficient amount of sensitizer, and 2) using heavy brush strokes at the end of coating when the sensitizer had begun to dry.

    And of course, start coating with the brush neither too wet nor too dry. What I learned from Kerik Kouklis about coating with the Richesoin was, first wet the brush and then shake out the excess moisture, but not so much that the hairs of the brush separate.

    Sandy
     
  4. donbga

    donbga Member

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    Jorge,

    Yeah I heard you :smile: Perhaps you heard me!

    I've tried to make sure that I've pre-wet the brush, perhaps it is just a little too wet.

    Thanks,

    Don
     
  5. donbga

    donbga Member

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    Sandy,

    I thought the low humidity might be the culprit although I humidfy my darkroom and try to keep it above 50%. I'm thinking that I may be stroking the paper a little to heavily as you mention.

    Thanks,

    Don
     
  6. rbarker

    rbarker Member

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    Don - when I read your subject in the index, I was afraid you had been arrested. But streaked prints might be almost as bad, I guess. :wink:
     
  7. Mateo

    Mateo Subscriber

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    Here two bits from a rookie for what it's worth.
    The humidity of the room is not the only thing I worry about. If it's been dry for a while my paper is too dry even if I humidify the room. After the weather has been a couple of days over 60% Rh, then it's ready to go. I guess you could store your paper in a humidity controled cabinet but that's not practical for me so I just wait for the weather to get better. When I use the Fabriano paper and presoak in oxalic, I can print in dry weather by just catching the paper at the right point of drying.
     
  8. photomc

    photomc Member

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    From another rookie, that just started using the 9010 - it's all new to me - have noticed the same results as Mateo. If the humidity has been low (as in <50%) and temp is cold (meaning the heat is running) the paper seems to need a little more humidity. Just set up a humidifer, so can't comment on results from that yet. You would think preping paper for 4x5 would be a snap, but not always. Does anyone know of a way to measure the mositure in the paper? Thought about finding that, because as Mateo stated, when you catch the paper at the right point in drying it seems to work great.
     
  9. Michael Mutmansky

    Michael Mutmansky Member

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    Are you single coating or double coating?

    If you are single coating, then I would suggest you also consider how much solution you are using, in combination with the humidity in the paper and moisture in the brush. If the paper is especially dry, it will soak up the solution fast, and you may end up not having enough to properly cover the image area.

    When I coat, the paper is very wet when I am finished, evenly coated, but wet, so there is some soaking and drying to be done by the paper.

    Before starting, I dip the brush in H2O so that it is soaked, and then shake it out (hard) about four times onto the ground next to the coating table. That seems to work very well.

    One more thing; I coat with the brush in both directions, left to right and back, and also up to down and back, all on the same sheet of paper. As long as you have enough solution, that should pretty much eliminate any streaking.

    These comments apply to Platine and Cot320. Other papers may require a different procedure depending on their absorption characteristics.


    ---Michael
     
  10. donbga

    donbga Member

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    Hi Michael,

    I'm using Stonehenge White and Fabriano Satinata this time around. Do you wet the brush with water before each print?

    I coated in both directions left to right and then top to bottom.

    Question: How are you initially dispersing the sensitizer on the paper? When brush coating I normally pour the sensitizer onto the center of the paper. I seem to be getting more sensitizer on the "top" half of the paper, suggesting that my technique is flawed. And I am double coating, BTW.

    The paper does appear to be very wet when I've finished coating and does appear to look evenly coated, I'm also adding a couple of drops of Everclear per ML of sensitizer. Do you try to overlap the brush strokes?

    Thanks,

    Don Bryant
     
  11. donbga

    donbga Member

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    Move your paper into the coating area at least a day before coating and humidify the coating room to about 60%. The paper will absorb water over a period of time.

    If the paper has a crackle to it then it's too dry. If it is too wet it will feel limp.

    Don Bryant
     
  12. Jorge

    Jorge Inactive

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    I pick the solution with a serynge and I put it on the paper along the wide edge. I then immediatelly start brushing. I never liked the pouring in the center technique, seems to me you get a lot of the stuff in the center and not as much in the edges.
     
  13. Jeremy

    Jeremy Member

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    I use the technique clay taught me where you use a shot glass and drag the solution down one side of the paper with the rim of the glass and start brushing. Once I got the actual brushing part down my coatings have been very even.
     
  14. shinn

    shinn Member

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    I generally know if I'm gonna have streaks before the paper is even dry, I was foolish enough to choose gum bichromate as the first hand coated process I tried and the thicker emulsions can be very troublesome but the most important thing I’ve discovered is knowing when to STOP brushing. If some emulsion is dry or at least more dry and you continue bushing over it you will get streaks more times than not. At least I do anyway.

    Happy Days
     
  15. sanking

    sanking Member

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    I coat pretty much as Michael described, brushing in both directions, left to right and back, and also up to down and back, all on the same sheet of paper, plus I also brush on the diagonal in both directions. The paper is fairly wet when I finish coating, but there should be no puddling.

    To disperse, I pour the sensitier right in the middle of the area to be covered, very quickly, and immediately spread it in all direction. I have not experienced any uneveness in coating this way.

    How much solution are you using? For an 8X10 print I double coat, using four total ml of sensitizer, 2 ml per coating, though I dilute the first coating 1:1 with water.

    Sandy
     
  16. donbga

    donbga Member

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    Jorge,

    Funny you should mention using a syringe, I was thinking of using this myself since this is how I always did it when using a glass rod.

    Don
     
  17. donbga

    donbga Member

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    I'm using 2ml per 8x10 per coat. I haven't been spreading the sensitiser evenly as you suggest. I'll amend my technique.

    Don
     
  18. Michael Mutmansky

    Michael Mutmansky Member

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    Don,

    I haven't used either paper, so I cannot comment specifically on them, so take my suggestions as educated guesses only...

    I often coat several sheets in a row. The first one gets a H2O dipped and shaken brush. After that, I don't bother as the brush is typically at the correct wetness for the rest of the sheets, and it is partially loaded with sensitizer, which is better to use for loading the brush anyway.

    I typically pur it in a long stream across the center of the sheet and rapidly spread it into the four corners, and then fill in the rest of the sheet. I will then brush L-R-L-R from the top to the bottom, and then T-B-T-B from left to right to ensure an even distribution of the solution. That's it. The paper will be really wet when I stop, because if it has started to go velvet, you may see streaking from buildup of sensitizer on the surface which will wash away in the developer.

    I've done some tests with Everclear, and it causes problems. In most cases, it makes the solution penetrate the sizing too quickly, and will result in streaking. Not to say that it can't be helpful for some things, but I haven't found a useful application in my pt/pd printing with the papers I am using (gum printing is another issue). I'd suggest dumping the Everclear.

    Are you thinking of PVA as a thickening agent? Everclear will essentially make the solution 'wetter' which will cause it to run into the fibers of the paper faster. PVA acts as a thickening agent, which will slow down the absorption. I don't use PVA either, but I did find it can be helpful, and it may increase the dmax of the print a little with some papers.

    I definitely overlap the brush strokes. I move pretty fast, so there isn't a whole lot of precision in the process, so I probably overlap the brush by 1/4 or so each time.

    Since you are double coating and still seeing streaks, my guess is that it has to do with the paper sizing, either a problem with the Everclear, or maybe a problem associated with the sizing in the paper or the humidity in the paper.


    ---Michael
     
  19. Jeremy

    Jeremy Member

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    I've been using one drop of vodka (didn't have any everclear in the bar) with just my first coat and it has worked wonders.
     
  20. DeanC

    DeanC Member

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    So, 4ml of liquid (of which 2ml are sensitizer and 2ml are water) in the first coat and 2ml of liquid (all sensitizer) in the second?

    Dean
     
  21. sanking

    sanking Member

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    That is a total of 4 ml of liquid, of which 3 ml is sensitizer and 1 ml is water. The first coating is diluted one part sensitizer with one part water, the second coating is straight sensitizer.

    In my work I see a signficant difference in Dmax between single coating and double coating with the first coating diluted with water, but little if any difference between double coating with the first coating diluted 1:1 with distilled water and double coating using straight sensitizer for both coatings.


    Sandy
     
  22. DeanC

    DeanC Member

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    Okay, so each coating is 2ml of liquid.

    Coating 1 is 1ml of sensitizer + 1ml of water.
    Coating 2 is 2ml of sensitizer.

    Great. I've got some 11x14 cot320 on the way for B+S, I think I'll cut some pieces into quarters and play with printing some step tablets over the weekend.
     
  23. sanking

    sanking Member

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    That is correct. And it is best to use distilled water. Tap water contains iron that may interfere with the process.

    Sandy
     
  24. donbga

    donbga Member

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    Jeremy,

    I thought about trying that method as well, I'll give it a go next time I print.

    Thanks,

    Don