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  1. #1

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    Has anybody got a successful calotype negatave?

    In the last months I've experimented salt printing and found out how to make decent prints

    The process is very easy and for anyone interested I can share my experience. For example, I noticed a slight difference of tone if you fix salt prints in 10% hypo solution or use instead a weak fixer for standard silver prints; the latter is more pinkish-purplish while classic hypo delivers a more brownish image (the difference is subtle).

    Salt prints have definitively a nice vintage-look. The highlights of my prints are never white, but I have some tone in the whites and this makes them more old-look like.

    In my efforts to make prints appear "antique", the next step was obviously to learn how to produce calotype negatives.

    While saltprint process is quite easy and straightforward almost like cyanotype printing, I met some difficulties with calotype negatives.

    In low tungsten light conditions, I first coat a sheet of paper with a solution of 11% silver nitrate (the same I use for salt prints), let dry and then immerse the paper in a solution of 5,6% potassium iodide. The paper turns primrose yellow, especially on the silver coated side. I leave the paper in the potassium iodide bath for 2-3 minutes, then I rinse it for about 1 hour and half. The paper is then hanged to dry. At this stage, the paper remains clear even if exposed to light; no stains or brown spots whatsoever, just a uniform faint yellowish tone in the coated side.

    The next day, under red safelight conditions, I prepare a solution of the following: to each five drops of a 11% silver nitrate solution I add a drop of 80% acetic acid; to each of these {5+1} drops I add an equal amount of drops (e.g. 6) of a 1% saturated solution of gallic acid. Then add 8 ml of distilled water.

    While still in red safelight conditions, using a clean brush I coat the previously iodized paper with such solution. At this point, though, the paper turns dark... Not completely black, but visibly darker. I'm quite perplex, I guess there's something wrong.

    In fact, after I finished coating, I put the sensitized paper in a 4x5" sheet holder (the paper was initially cut to fit the size) and expose it using a normal large format camera. I tried exposures ranging from 2' - 5' at f8 in a sunny bright area.

    When I bring the sheet holder back to the darkroom and open it is almost gray as it was before, perhaps slightly darker. I try to develop the paper using an equal amount of silver nitrate and gallic acid (plus one drop of acetic acid every 10 drops of silver nitrate). The paper turns really dark, totally black. I wait for 1-2 minutes and the situation doesn't change. By fixing the paper in a standard hypo solution, the paper just stay black. I can tell the "black" has the same tone of calotype negatives I've seen around the internet, but still is black and I can't see anything on it.

    What do you think went wrong? Should I try another kind of paper? The one I used is a schoelleshammer and should be a rag paper... It seems to take the iodizing stage quite well. It's the silver gallo-nitrate sensitizing part that produces an odd result. The paper should remain clear while sensitized and become dark only during a quite long exposure to sunny light....

    The silver nitrate and the potassium iodide alone don't seem to react badly to the paper, otherwise I would have brown stains and spots. Could it be something wrong between gallic acid and silver nitrate?

    Does anybody have some experience with calotype negatives?
    I could switch immediately to another kind of paper, before doing so I wanted to ask some help... The schoelleshammer 6 paper is the smoothest and lightest paper I have here; I got some zerkall, fabriano 5 and arches acquarelle and platine, but they're all relatively heavier and rough.

    thanks

  2. #2

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    ok... so far while I was experimenting different dilutions of the sensitizer, I found the following:

    regardeless their proportions, combining acetic acid (80%), silver nitrate (11%) and gallic acid (1%) in distilled water does not produce visible changes in the color of the solution, which remains transparent (in safelight conditions); but if I bring this solution in contact with the previously iodized sheet of paper, this turns immediatly black.

    This solution turns black only when I put it in contact to the iodized paper. So, I tried to put each element of the sensitizer on the paper separately.

    First I've dropped a single drop of silver nitrate directly on the iodized paper: nothing happened; but when I added to this a drop of gallic acid... whooom... I got an instant black spot on the area even under red light. The same happens if I invert the order and put one drop gallic acid first and then a silver nitrate one.

    By mixing silver nitrate and acetic acid (in a<b proportions) before adding the drop of gallic acid, the blackening is less effective, but still makes the paper useless for camera exposure. So, I tried altering concentrations of the chemicals, but so far I haven't got a working combination of the three.

    According to my sources, the paper color should not change after the iodizing part, which turns its color slightly yellowish. But as far as I can see there's a reaction between silver nitrate and gallic acid when both enter in contact with the iodized paper that produces an instant coloration of the paper itself without any exposure to considerable light.

    What do you think?

    F.

  3. #3
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    Perhaps the paper was exposed to light after the silver iodide coating?

  4. #4

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    Quote Originally Posted by htmlguru4242 View Post
    Perhaps the paper was exposed to light after the silver iodide coating?
    mmm... but the iodized paper isn't light sensitive, is it?

    I mean, some sources even mention the possibility to expose the iodized paper to sunlight prior to sensitizing for a couple of hours to improve final contrast...

    I don't do that.

    All I do is to coat the paper with 11% silver nitrate first. After drying with an hairdryer, I leave it in a bath of potassium iodide for 2-3 minutes. These operations are made under a 40w tungsten light bulb, the same I use for saltprints and vandykes without any visible fogging. After iodizing stage is complete, I wash the paper for at least 1 hour, under the same light (or no light at all if I leave the room). The paper is finally hanged.

    Initially I made some mistake and brushed the potassium iodide on the paper directly, instead immersing it in a bath of the same solution. I've soon realized that the potassium iodide must be a lot more than silver nitrate to convert the latter. It has to go also on the back of the paper. Without using a full bath, the paper will show typical silver nitrate brownish spots when placed in the washing bath (I guess as a reaction to organic matter present in tap water and light - organic matter is what makes silver nitrate light sensitive as far as I know).

    When I started immersing completely the silver nitrate coated sheets into a solution of 5.6% potassium iodide, all brown spots disappeared. I still got some iodized papers here that haven't been sensitized yet. I iodized those 3-4 days ago and they show no spots or stains: just an uniform white-yellowish color which should be normal at this stage.

    Problems seem to start appearing now at the sensitizing stage.

    Anyway I could make some test and doing all the operations under red safelight if you think so.

    Have you ever produced some good calotype so far?

    thank you very much

  5. #5
    htmlguru4242's Avatar
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    I do not have experience with Calotype, but based on your procedure, i think that that could be the issue; I could be completely wrong, but the way I see it ...

    Silver nitrate + Potassium Iodode yeilds silver iodide, which is light sensitive; it is not extremely sensitive, and it does not print out like silver chloride does, though it is light sensitive. Over an hour in tungsten light, it becomes exposed from the light that is present.

    Gallic acid and silver nitrate functions as a photographic developer. Therefore, when it is coated with this solution, it develops out the exposure.

    Try coating the iodized paper under safelight.

    That's just my suggestion based on reading and (perhaps flawed) logic.

  6. #6
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    Silver iodide is quite light sensitive. Sensitivity extends far into the visible region of the spectrum. In fact, pure silver iodide is almost ortho sensitive all by itself with no sensitizing dye.

    It cannot be developed by conventional developers, and that is why calotype uses the process it does. Silver iodide made this way also produces very fine crystals and that is why the speed is rather slow.

    PE

  7. #7
    htmlguru4242's Avatar
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    That's interesting, PE

    How is silver iodide developed, then?

  8. #8

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    ok, I'm convinced, I'll do all the iodizing part in red safelight, including washing of the print. Tomorrow we will see if that was the problem.


    thanks

  9. #9

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    Quote Originally Posted by htmlguru4242 View Post
    Try coating the iodized paper under safelight.
    I do sensitize my already-iodized papers with gallic acid + silver nitrate under safelight, as prescribed in my books. What I do in standard tungsten light is the previous iodizing part (silver nitrate coat, then potassium iodide bath). Tonight I'll try doing that under red light as well, including washing.

    thanks, I will post details if it works

  10. #10
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    Development of silver iodide is done as described above for calotypes.

    It can also be done with very high strength alkaline developers, but I have not seen this done for over 30 years. I know it can be done, but it is very very difficult in most cases and I'm sorry that I have no specific developers to suggest.

    PE

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