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  1. #1
    Rudeofus's Avatar
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    Ilfochrome processing for the home/photoclub amateur

    For some years I have shot color slide film almost exclusively because I loved the colors and it was (for me) much easier to scan than negative film. Needless to say that sooner or later I began researching ways of printing some of my favorite slides directly to paper.

    Ilfochrome and internegatives were the two choices left for this, and since I did not want to fiddle with internegatives I focused on Ilfochrome, maybe also because most related forum posts rated Ilfochrome as top of the crop with breath taking colors and longevity measured in centuries, not years. Well; i can at least confirm the breath taking colors now.

    Fortunately and thanks to the digital "revolution" dark room equipment has become available in the used market at very affordable prices, so I could use things like density measurement devices, temperature controlled drum processors and color enlargers which would have been completely out of my reach just a decade ago.

    After a short (and ongoing) foray into B&W dark room printing it was time to figure out how to apply my recently acquired B&W dark room skills towards Ilfochrome printing. While there were several resources and postings available online about how to make this process work, there were quite a few questions left unanswered for me:
    • Where do you get the raw materials from ?
    • How to you do test strips without wasting excessive amounts of paper and chemistry ?
    • How do you accurately cut Ilfochrome paper to size ?
    • How do you practice the routines without wasting a fortune on paper and chemistry ?
    • How do you determine initial processing parameters ?
    • Which slides can I print without a contrast mask ?
    • How do I achieve color balance ?


    Sources of Ilfochrome Material
    First of all, one must know that there are two Ilfords on the market right now which operate in related fields but are otherwise mostly unrelated.

    The first one, and probably the one more known to most dark room printers, is ILFORD PHOTO, the company now mostly focused on black and white film and paper and is also prominently represented here on APUG by Simon R Galley. The other Ilford, and the one responsible for Ilfords color products, is Ilford Imaging, a company notorious for ignoring email inquiries and generally very unhelpful to the amateur community.

    Fortunately they do provide a list of distributors on their web page. These distributors may not ship directly to non professional end customers, but they at least answer questions about who actually does carry the Ilford Imaging materials and is also willing to supply these materials to people like me. In my case, I was supplied with a few addresses of local suppliers, one of which was even willing to order the material for me.

    So what is available and what will you need for initial experiments?

    First of all: the chemistry. It probably doesn't really matter which kit you get, it mostly matters that you get this kit shipped to you or your dark room location. I have read multiple reports that these kits are not shipped abroad or anywhere at all by some listed retailers. The kit I was finally able to get was KIT30.2 of the P30 chemistry, which is interesting since the Ilford imaging web page doesn't even mention this kit at all (not even under discontinued products), but it's listed on several distributors inventory lists as available. Mixing instructions for this P30 kit are very different from the P3 instructions, so be careful which one you get before you follow online instructions.

    Second: the paper. There used to be a range of different papers but again, one has to take what one gets. Chances are you'll get the CLM.1K paper, ideally in 20x25cm sheets which is the smallest size available. The data sheet for the paper lists both CLM.1K and CPS.1K as suitable for analog printing, the CPS has more contrast.

    Important Little Facts and Mythes about the Ilfochrome Process
    Here are a few important things I learned from other Ilfochrome related postings or from other members here who answered my questions here in this forum.

    The main challenge of the Ilfochrome process seems to be to dial in optimal process parameters and from then on try to reproduce them as accurately as humanly possible. The main goal of this is to exclude all possible variation from the process so that the absolutely only thing which changes your color balance is if you modify the filter setting on the color head of your enlarger.

    If you look at the (very brief) instruction manual which comes with the chemistry kit, you'll see a very rough description of the process, like dev times: 3 minutes @ 24°C, 2-3 minutes @ 30°C. This indicates that the process works well at all these temperatures but the results may turn out quite different if you change the process temperature from 24°C to 30°C. Consistent processing also includes fully repeatable washing cycle after the dev step and using a completely dry drum before paper is inserted.

    Another important thing I learned was that one can judge the results only after thoroughly washing the paper and fully drying it. Colors do change a bit while the paper dries and you do not want to optimize color filtering for a state which inevitably changes once the paper is dry.

    Allow me a few quick paragraphs about the often stated high contrast of Ilfochrome. If you look at the data sheet for CLM.1K paper, you will see that this paper maps a density range of 2 from the slide into a density range of 2 on the paper, which means it does not change the contrast of the input media. The reason so many complaints about its contrast are made is that slide film is capable of more contrast than Ilfochrome paper can accept. If one remembers the zone system, the whole point of it is mapping the whole range of input contrast onto the negative and then putting the whole range of the negative onto paper without loss of information. Pushing and pulling is used to control the contrast of the negative, and paper with different or variable gradations is available to control output contrast. With slide film and Ilfochrome we often don't have these options: slides are supposed to look good in the projector, so we can't mess with contrast all that much. And the paper itself has fixed contrast, so no help from there either.

    The good news is this: while good slide material can have huge contrast, mine never did, since I always tried to scan them and my scanner couldn't make use of 3 logE density range anyway, much less could I use it when creating JPEGs from my scans. So instinctively I shot pics with reduced contrast range all the time, using flash to brighten up shadows, polarizer filters to bring down the sky and generally avoided sceneries with too high contrast. This may have turned my slide portfolio into dull images which will never win prizes and won't be shown even in regional free news papers, but when it comes to Ilfochrome printing my slides absolutely rock, since I don't need contrast masks or anything.

    In case you worry about the contrast range of your favorite slides: Ilfochrome paper has about the same contrast as low gradation B&W paper. If you want to see whether a slide would print well with Ilfochrome, just enlarge it to a B&W paper at gradation 0 or so and see whether it shows detail in all areas. The tones will be, of course, reversed but that doesn't matter for this experiment. If you have a density meter, you don't even need to waste B&W paper on this.


    Conserving Paper and Chemistry
    If you see the prices for Ilfochrome chemistry and paper you will quickly understand why this is an important topic. Chemistry prices are even more important to the casual user since you will most likely run the chemistry one shot. Required quantities are more dependent on paper drum size than on paper area inside the drum, which means you'll waste a disproportional amount of soup on the first few test strips.

    The good news is, that once the process is dialed in you rarely need further test strips, assuming you keep everything else in your process consistent. But do note that different paper batches may need different filtration, so be prepared for future test cycles before you fully control the process.

    Try to find out how little chemistry you can use in your paper drum. Try this with B&W paper and chemistry because it really doesn't depend on the process which amount of liquid is required to cover your print material. Note that if your drum does not stand perfectly straight you will need more soup than calculated from pure geometric view. When I did my first experiments with B&W paper in the drum I observed the following outcomes with increasing quantity of chemistry: At 40 ml the paper only showed my finger prints in faded black, while nothing of the image was visible. At 60 ml the image was clearly visible, but I had white streaks towards the center of the image. Only at 80 ml the image came out fine. These numbers may be way off for your particular paper drum, so I really encourage you to do the test yourselves. B&W paper and chemistry are cheap, much cheaper than ruining a nice Ilfochrome with too little chemistry and also cheaper than wasting lots of chemistry that wouldn't be necessary.

    Then try to find out how small a test strip can be. Since you will use the chemistry single shot at least for you first experiments, it is more economical to run one large test strip which covers many variations in exposure and/or filtering than multiple runs of tiny test strips. It depends on the drum which sizes of test strip you can process.

    Getting the Right Sizes of Ilfochrome Paper
    The Ilfochrome process was (also) used by a few dedicated amateurs in the past but is now almost exclusively in the hands of a few remaining pro labs. These labs have dialed in processes, have custom equipment to support the procedures, and for whatever reason they don't seem to need paper smaller than 20x25cm. As a result, 20x25cm paper was the smallest I could order, which may be a nice format, but is definitely unsuitable for test strips or the first dozen or so experimental prints.

    First I tried to figure out which strip sizes would actually fit in my print drum. Take a ruler and card board to cut test strips and see how well they fit. While the length of the strip can be chosen freely, it's width must be correct to the millimeter, otherwise it would either not fit or fall out during processing. The sheet needs to run close to the talk wall or it won't be covered by the chemistry in the center.

    So how do you turn 20x25 cm sheets into smaller sheets in full darkness? Since I know of no machine which would do this for me, I had to construct something for myself. Here is what I did: I took some wooden board, about 30x30x2 cm, and attached a small board (30x4x2cm) to one of its sides, so that it would only stick out on the top side. Think of this side view: |________________________________

    The point of this is that you can lay a sheet onto the board and shove it against the rim so it is in a well defined location in this direction. I then had a glazier cut a few glass plates with very precise width. I would lay such a glass plate onto the Ilfochrome sheet and have a precise guide for a Stanley knife. This allowed me to cut the sheet to size without seeing anything in the dark. I recommend you draw out a cutting plan for your sheet before you have the glass plates made. Since my paper drum can hold a sheet 12.7 cm wide and little over 10 cm high, I was able to cut the 20x25cm sheets (which are 8x10" sheets, i.e. 20.3x25.4cm) into 4 sheets of 10.1x12.7cm. I also cut one sheet into 3 sheets of 6.7x12.7cm, 4 sheets of 4.9x6.7 and 4 sheets of 4.9x6cm, if I remember correctly. I could do all this with the following glass plate sizes: 4.9x15cm, 6.7x15cm, 10.1x15cm and 12.7x25cm. Note that Ilfochrome paper is very hard to cut, so make sure you have a sharp knife.
    Trying to be the best of whatever I am, even if what I am is no good.

  2. #21
    Photo Engineer's Avatar
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    And, I might add, that the coatings are far far simpler than Kodachrome! We handcoated Ilfochrome in our lab at EK, at least a serviceable example. If we had continued it would have been fully functional as we hit it pretty much right on, first try.

    PE

  3. #22
    Rudeofus's Avatar
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    Wow, hand coating Ilfochrome .... can you give us any indication whether the chemistry involved in this is obtainable by random home brewers? Is this something we could remotely consider doing once we run out of materials?
    Trying to be the best of whatever I am, even if what I am is no good.

  4. #23
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    I have given the entire process sequence elsewhere here. Right now, I am tied up with a workshop and cannot dig out the information. Sorry. I cannot even find the original single layer strips that I made to show feasibility. One was damaged and I had planned to make another set.

    PE

  5. #24
    Rudeofus's Avatar
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    I've spent some time searching for Ilfochrome recipes on APUG and here is what I found so far:
    • I found this thread where a lot of chemistry is thrown around. Unfortunately brookse never posted a specific recipe, but he seems to have one.
    • Here is a thread with some more info and a recipe which is said to work poorly.
    • Here is another thread with a recipe. And another one. And one more.
    • A number of threads recommend Dr. Beers developer to replace the Ilfochrome dev. Here is the recipe.
    • Following the advice in these threads I searched for "dye bleach ciba patent" and boom, a long list of patents (like this one and that one from EK) describing dye bleaches and referencing other patents on that topic.


    A long list of odd ball (to me) chemistry is mentioned but some are obtainable from Sigma Aldrich: 2,3-Dimethylquinoxaline, 2-hydroxy-3,6,7-trimethylquinoxaline, Sodium 3-nitrobenzenesulfonate, Phenazine, Quinoline and N,N-Dimethyl-4-nitrosoaniline.
    Trying to be the best of whatever I am, even if what I am is no good.

  6. #25
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    All of the exotic catalysts will work. The 2, 3 Dimethyl quinoxaline is what Ilford uses AFAIK. I am intending to design my color material (If I ever go it) around Phenazine probably. IDK.

    All of the above are rather toxic and should be handled carefully and all DB bleaches are similar. They are about pH 1 or so, have HCl or H2SO4 in them, Thiourea, NH4Br, and other things. Recent DB bleaches use Sulfamic Acid with the same low pH.

    You must used a support such as YUPO or RC, as the bleach destroys most papers.

    PE

  7. #26
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    The MSDS and many other descriptions I found online claim that 2,3,6-trimethyl-quinoxaline are used by Ilford. This substance, however, seems to be difficult to get, at least Sigma Aldrich doesn't seem to carry it. The Ciba patent mentions that very good results are obtained if a mix of two catalysts are used which have different redox potential, and based on that patent a combo of 2,3-dimethyl-quinoxaline and 2-hydroxy-3,6,7-trimethylquinoxaline could be very promising. I have, unfortunately not delved into this deeply enough, but the Ciba patent does mention patents which could provide useful recipes.

    About paper support: could bleached and fixed b&w paper do the job? I have tons of b&w prints that only highlight my poor photographic skills which could be repurposed for this.
    Trying to be the best of whatever I am, even if what I am is no good.

  8. #27
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    Someone has described elsewhere on APUG, how these quinoxalines may be easily made by simpler chemicals. Unfortunately, the scheme uses p-Phenylene Diamines and the real synthesis uses o-Phenylene Diamines. Mix the right one with Diacetyl, and in one step you have the Quinoxlaine. Easy one step.

    Not explosive, nor very corrosive.

    FB papers are not a good idea here. RC would work.

    PE

  9. #28
    Rudeofus's Avatar
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    Since I can get quinoxaline and some variations of it at reasonable cost (compared to cost of Ilfochrome paper and given that it is used only in small amounts), I think I will just plunk down money for the real thing.

    Here is my home brew strategy:
    • Replace Ilfochrome fixer with OlepH 6.5, which is based on Ole's quick fix but has pH adjusted to 6.5
    • Replace developer with Dr. Beer's developer and make sure that color balance can be restored. Experiment with different contrasts.
    • Once this is all figured out, play with dye bleach. I guess I'll start with sulfamic acid for pH of 1, various amounts of 2,3-dimethyl-quinoxaline and 2-hydroxy-3,6,7-trimethylquinoxaline and 50g/l of NH4Br. You also list thiourea, can you tell me what that is supposed to do in the dye bleach?


    One thing which honestly surprises me about the process is the extremely relaxed attitude towards fixing. Although it is supposedly archival, they use sodium thiosulfate for two minutes without much fuss, compare this to the complex procedure recommended even for plain b&w RC paper!
    Trying to be the best of whatever I am, even if what I am is no good.

  10. #29
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    Thiourea is a fixing agent that helps accelerate the dye bleach reaction.

    Since the "paper" is really plastic, the wash will proceed rapidly in the fully swollen emulsion. But, be careful. There are known cases of browning of Dye Transfer prints due to under fixing and/or under washing.

    I do not recommend storing chromogenic and dye bleach prints together. You will notice a strong odor from the dye bleach prints after a few years. IDK what the reason is.

    PE

  11. #30
    Rudeofus's Avatar
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    Quote Originally Posted by Photo Engineer View Post
    Thiourea is a fixing agent that helps accelerate the dye bleach reaction.
    Any hints about recommended concentration of thiourea in such a dye bleach?
    Trying to be the best of whatever I am, even if what I am is no good.

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