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  1. #21

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    Quote Originally Posted by Lukas Werth
    Willie Jan,

    Just to make shure: New c. sensitizer, as I know it, always looks somewhat greenish when out of the bottle, and if you look from above into the brown bottle, it may even have a bluish tinge. When coated onto the paper, however, the colour must be of a bright yellow, and this yellow colour must remain, and not turn into green. So my question is: when coated onto Bergger, presuming that it looks yellow at least at first, does it stay so or does it turn into green?
    Willie Jan

    As Lucas stated, the sensitizer should remain yellow. If you add K3CR2O7 then it goes brighter yellow. Green would indicate partial exposure or contamination IMO

    Phill
    It is not tradition that secures the survival of our craft, its the craft that secures the survival of our traditions.

  2. #22
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    Quote Originally Posted by philldresser
    Willie Jan

    As Lucas stated, the sensitizer should remain yellow. If you add K3CR2O7 then it goes brighter yellow. Green would indicate partial exposure or contamination IMO

    Phill
    Phil what paper do you use?

  3. #23
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    Quote Originally Posted by Lukas Werth
    Willie Jan,

    Just to make shure: New c. sensitizer, as I know it, always looks somewhat greenish when out of the bottle, and if you look from above into the brown bottle, it may even have a bluish tinge. When coated onto the paper, however, the colour must be of a bright yellow, and this yellow colour must remain, and not turn into green. So my question is: when coated onto Bergger, presuming that it looks yellow at least at first, does it stay so or does it turn into green?
    Lukas i will put a drop onto a glass surface today and have a look if the color is yellow and after that check the paper.
    I always work under red light when coating....

    Could a brush with an iron end do some harm to the liquid when brushing?
    I now have a glass rodd, but before i used a brush.

  4. #24

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    Don't coat under red light, you only don't see what happens. Weak normal bulb light is completely adequate, though it is probably better to avoid tubes. You want to see and check the sensitizer and the surface clearly when coating.

    I personally use brush and rod, and my brushes have metal holdings which inflict no harm whatsoever; just always wash after use, and use them wet. By the way, I use those flat brushes with soft synthetic fibers used for varishing and the like, they use as little liquid as a rod, and don't shed. On some papers, with some processes I prefer rods, on others brushes. Do you use Tween 20?

  5. #25

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    Quote Originally Posted by Davec101
    Phil what paper do you use?
    Dave

    I've been using Arches Aquarelle Hot Pressed 300gsm. It works best on the rear of the paper for me

    Phill
    It is not tradition that secures the survival of our craft, its the craft that secures the survival of our traditions.

  6. #26

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    Quote Originally Posted by Lukas Werth
    Don't coat under red light, you only don't see what happens. Weak normal bulb light is completely adequate, though it is probably better to avoid tubes. You want to see and check the sensitizer and the surface clearly when coating.

    20?
    I agree here. Use normal tungsten lights (Mine is 60 watt @ 1.3 meters. No problems with 20 min exposure. However the tubes in the garage/darkroom cause density after 3 mins.

    Phill
    It is not tradition that secures the survival of our craft, its the craft that secures the survival of our traditions.

  7. #27
    Willie Jan's Avatar
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    i did a test and the liquid is very very light green.

    The photo on alternative.com with cyanotype how to coat the paper picture where the guy who is using a glass rod to coat the paper shows a pale yellow, but this is not the case with mine ( i think he used something else..).

    I glass rodded a little piece of fabriano and bergger cot 320. After coating and drying the cot 320 looked a little more green than the fabriano. Next day the cot did turn towards the blue and the fabriano stayed as before.

    But what i did wrong was that i used the backside of the cot 320 paper... So i will do the test again this evening with the right side up to see what happens...

  8. #28
    Willie Jan's Avatar
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    i did a new test on the bergger 320 (on the right side of the paper).

    It was light green after drying, next morning it still was light green.

    Conclusion:
    This would mean that the cot 320 is appropriate for this job.
    The fabriano turns towards blue after one night.

    Or is there paper where the liquid stays yellow?
    The Blueprint to cyanotypes book says that it turns light green and it does.

    Willie Jan.

  9. #29

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    Willi Jan,

    the Bergger paper is inadequate, don't use it for this process, at least not untreated. The sensitizer has to remain yellow when dry, as it must appear once you coated it on the paper, or otherwise the image will be fogged. (By the way, this means that the paper may not really be first-rate for other iron-salt processes, too)

    Blue is worse than green, but that result on untreated Fabriano (artistico, isn't it?) was predictable, since this paper contains an alkaline buffer, as do most papers today: this is a selling argument to make them more resistant against environmental damages.

    You may try to immerse both papers in 1% hydrochloric acid for about 5-10 minutes, with occasional rocking, wash the acid out in a short clear water bath, dry, and then coat again. Very likely you will find that the sensitizer remains yellow in this way, but with Fabriano Artistico I still have often problems with blotches appearing only after the paper has been exposed under the negative. Sometimes, if you are lucky, they wash away when you give the first wash in 1-2%hydrochloric or (I think?) nitric acid, but often enough they don't, enough to make the printing experience with such papers frustrating. I now use Fabriano treated in such way for test strips, as I don't want to waste the expensive Buxton in this way.

    By the way, I don't seem to know the book you refer to. What is its exact title? And, I would think that for traditional cyanotypes also, the sensitizer has to remain yellow if you want first-rate results (and otherwise, why bother?).

  10. #30
    Willie Jan's Avatar
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    this is the book.

    http://www.alternativephotography.co...yanotypes.html

    I'll try it with the acid.
    1% solution. The chemical is delivered here as 30% solution,
    so i must add 3ml acid at 97ml water?

    Willie Jan.

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