Contrast of Cyanotypes

Discussion in 'Alternative Processes' started by fhovie, Dec 18, 2004.

  1. fhovie

    fhovie Subscriber

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    Greetings all:

    There are many images that call out to be in blue but it seems I need to expose at N-2 to get a normal looking Cyanotype. The stuff it just too contrasty. Sometimes that is good and many images get very snappy with it but I was wondering if there was an easy way to reduce the contrast of a cyanotype. I have seen some artists cyanotypes that appear very low in contrast. Are they doing it with the development of the film? I typically develop for AZO/ Amidol and hope it will make a good Kalitype. TRI-X at ASA200 in PyrocatHD for 14 minutes in a tray - 70F and 5sec agitation every 30 sec. - I believe that gives me a little extra contrast (N+1?) to go with the greater denisty for alt processes.

    Any ideas?
     
  2. Mateo

    Mateo Subscriber

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    I'm curious about how you're getting contrasty cyanotypes. The best ones I've made were with negatives intended for pure Palladium and they are extremely contrasty.

    Is it possible that you're losing high value density in the wash?
     
  3. smieglitz

    smieglitz Subscriber

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    Try varying the proportions of the compunent parts. I believe the proper mix to reduce contrast is 2 parts Ferric Ammonium Citrate solution to one part Potassium Ferricyanide solution instead of the usual 1:1 ratio. You may need to increase exposure a bit to compensate.
     
  4. fhovie

    fhovie Subscriber

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    I don't know - I wash them in cold water, gently - I let them take their time until I am certain all the yellow is gone. - I am using Crains Plainotype paper or Rising Stonehenge paper and I am using 1.2g Ferric Ammonium Citrate .6g Potassium Ferrocyanide in 20ml water. - I use between 3 and 4 ml to coat an 8x10 area on a 11x14 sheet using a Richeson brush. Is there something in my process or materials that is causing it?
     
  5. Mateo

    Mateo Subscriber

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    It very well could be too much contrast in the negative and for such the best remedy would be to use the self masking property of the process. But at some point of overexposing the print you will block up the shadows.

    Nothing in your materials seems weird but the devil is in the wash water. If you put a half a teaspoon of citric acid per liter of water and then use distill water for the final rinse, the alkaline tap water issue should be solved (if that is the problem). I've been using four trays to wash cyanotypes and acidifying the first three. I've also noticed that they are sensitive to being over washed. Hope some of this helps.
     
  6. smieglitz

    smieglitz Subscriber

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    I presume that is a typo and you are using ferricyanide, not ferrocyanide. I believe the usual formula is 1 part of 20% Ferric Ammonium Citrate to one part of 8% Potassium Ferricyanide. Your measurements don't equate to this (you have the equivalent of 12% citrate and 6% ferricyanide solutions if I've ciphered correctly). It appears you are using a mix with a higher relative proportion of the ferricyanide component so you are probably getting higher than normal contrast with your mix.

    You may also wish to investigate acidifying your water wash using a weak citric acid bath (or weak stop bath) added to the wash. Extended wash times, especially in alkaline water, will bleach the cyanotype. Clearing the print in a 2% citric acid bath may help get rid of the yellow quicker and more efficiently. Follow this by rinsing in running water for a couple minutes.
     
  7. fhovie

    fhovie Subscriber

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    Ok - so here is the fix?
    Add more Ferric Ammonium Citrate try maybe 1.5g instead of 1.2g all other things being equal, and then add some citric acid to the first and second wash. And if that moves things in the right direction, add even more Ferric Ammonium Citrate say 1.8g and see. - I believe the formula came from unblinking eye or some other web page. I get the most amazing blues with it - very deep - very brilliant. Many cyanotypes I have seen look muddy in comparison - but then there is the contrast ...
     
  8. Ole

    Ole Moderator Staff Member Moderator

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    I use a pinch of oxalic acid in each solution. I don't know if it does anything for the contrast, but it gives me good prints - so I'll continue doing it.
     
  9. smieglitz

    smieglitz Subscriber

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    Well, if I have my facts straight and the math done correctly you need 2.0 gm of the citrate and 0.8 gm of the ferricyanide in a total of 20ml *normal contrast* cyanotype solution. (Same chemical ratio as your 1.5:0.6 but a different water volume is needed. The amount of water in the mix will affect the emulsion speed from what I've read. I suspect your suggested mix would be slower.) For lower contrast you would approach 4.0 gm citrate and 0.8 gm ferricyanide in the total 20 ml solution.

    Personally, I would mix a larger volume quantity of both solutions separately, perhaps 100 ml or more of each and combine them in various proportions just before use depending on the contrast desired. For example, I'd use 12 ml of the 20% citrate stock solution to 6 ml of the 8% ferricyanide stock to get the low contrast mixture. (Or mix 18 ml citrate solution to 9 ml ferricyanide solution and toss the excess 7 ml if the 20 ml total volume is critical. The stuff is pretty cheap and environmentally benign.) I usually mix 1000 ml of each stock solution at a time. Other than having to filter out a little mold from the citrate bottle once in awhile, both stock solutions last a very long time. And, a few drops of a concentrated thymol solution in the citrate stock solution will prevent mold growth in that bottle for weeks.

    I use the initial 2% citric acid clearing bath and acidify all the later washes with a splash of said acid. I even acidify the final peroxide bath with a few drops of 2% citric acid to help ensure the environment remains acidic during all phases of processing.
     
  10. fhovie

    fhovie Subscriber

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    I would prefer to mix up fresh each time - 20ml gives me enough to screw one or two up - I will try these and see - I sure appreciate the help - Thanks all!
     
  11. donbga

    donbga Member

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    There is really no need to mix fresh solutions each time you print. Both A & B parts will stay "fresh" in the bottle. You will need to put some perservative in the part A jug to retard mold. I mix 1 liter of A and B at a time.

    When you coat use 2 parts A to 1 part B. Works every time.

    Don Bryant
     
  12. Gustavo_Castilla

    Gustavo_Castilla Member

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    Try Using baking soda about 1 tsp for 2 quarts of water ( it will do about 3 prints)
     
  13. John_Brewer

    John_Brewer Member

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    That's what it sounds like to me. The negative you want to use for a cyanotype - what grade of normal silver gelatine paper will it print on reasonably well? What are you using for your UV lightsource and for how long an exposure?

    J
     
  14. psvensson

    psvensson Member

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    Yes, you're probably getting high contrast because most of the image washes off in water. To retain the exposed highlights, you need a strongly acidic first bath. Mike Ware recommends a bath of 1% concentrated mineral acid. Not wanting to mess with concentrated acid I use a tablespoon of citric acid in 1.5 l water. Too lower paper contrast further (by increasing maximum density) add 1/4 tsp ferricyanide to the bath.

    Without the first bath I would need negatives with a density range of 1.1 to print cyanotype. With the first bath, I use negatives of about 1.8.
     
  15. Donald Qualls

    Donald Qualls Member

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    FWIW relative to the ferric ammonium citrate solution -- I've got a couple half-liter jars of it (dark glass with tight, black plastic lids) that are just over a year old, and there's no trace of mold in the one that's been opened several times for use. I did mix the stuff originally with distilled water instead of tap water, that might make a considerable difference (no spores in the water to begin with).