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  1. #21
    Digitaltruth's Avatar
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    Ron,

    In your follow up post, you state that ALL commercial developers failed to match Dektol in the one-off 10-day open tray test. Why didn't you mention this before? How did Tektol fare compared to other developers?

    As in the past, you have justified your claims by stating that the test you conducted was standard procedure at Kodak. Surely Kodak did not perform only this single extremely limited test on its developers. What other tests did Kodak conduct when assessing a developer, and how do Dektol and Tektol match up in those tests?

    Did you attempt to run any tests in which it was likely that Tektol or other Silvergrain products would show their superior qualities?
    --Jon Mided

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  2. #22

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    Quote Originally Posted by aldevo View Post
    I suspect Clayton, Ilford, Champion, A&O, and whoever owns EK's chemistry unit would disagree.

    In an era when product choices are diminishing the announcement of any new product line is most welcome.
    Somewhat off topic, but a lot of people asked me. "If you can make such products why don't Kodak, Fuji and Ilford make them?" That's a good question. I don't know.

    One thing I can tell though, they all tried. Those major companies own numerous US, European and Japanese patents on technologies they thought would be useful in eco-friendly processing chemicals. Based on my research, very few of them are actually used. Ilford, for example, holds a very broad US patent for concentrated ascorbate developers, although I don't see any of their products using it. Kodak has a number of patents attempting to improve the keeping qualities of ascorbate developers. What's the problem with them? In my test replicating some of their findings, their technologies worked better than some older ones but not good enough to make it commercially available. But those patents still have legal power of exclusionary rights to prevent me from using their findings.

    I off course worked around all patents that I was aware of, even ones I believe to be easy to nullify in court, but patents are written to make it difficult for the competitors to work around and still come up with something useful. (As a principle I try to avoid infringement for published formula, products, or something for my personal use, as I expect others do the same.) So these companies holding patents and not utilizing the technology are actually slowing down the technological progression. But you can't really blame them much. The market is shrinking and introducing any product costs a lot of money.

    Then Kodak and Ilford switched their strategy... rather than avoiding hydroquinone, they argue hydroquinone wasn't all that bad if you look at recent researches. Well, maybe hydroquinone was not as bad as it was once thought (depending on which research you look at). However, hydroquinone is listed on the regulated chemicals but vitamin c isn't. I believe they would replace hydroquinone if they had an option to replace hydroquinone with vitamin c without sacrificing the developer performance, ease of use, shelf life, etc. and without increasing the cost. Well, I don't have a technology to meet all those requirements; the manufacturing cost of Tektol is higher than equivalent PQ or MQ developers on market due to higher cost of ingredients and special mixing instructions. I don't get to decide the product's retail price, but I said to Jon that I hope people shouldn't have to pay extra to get the new technology. On top of that he is OK with me keeping the DS-14 formula posted on APUG and on my website.

  3. #23
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    I don't know what happened to the patent regulations since I tangled with them. One cannot patent the laws of nature, only specific uses of them. One cannot patent prior art, even if that prior art is not patented. It seems from what I have seen of some current patents that one could patent "a mixture of any of several photographic reducing agents with any of several antioxidant chemicals and any of several alkiline chemicals for the purpose of " you name it. Such general patents may not stand up in court, but they serve the purpose of hindering those who are not wealthy enough to hire a patent attorney. I'm sure you know all this, Ryuji. It's just something I rant about from time to time.

    My only experience with patents was at NASA. We had patent attorneys. At the time, there was a cigarette commercial, the theme of which was "I'd rather fight than switch." We used to say our attorneys would rather switch than fight. Oh, well.
    Gadget Gainer

  4. #24
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    Quote Originally Posted by Digitaltruth View Post
    Ron,

    In your follow up post, you state that ALL commercial developers failed to match Dektol in the one-off 10-day open tray test. Why didn't you mention this before? How did Tektol fare compared to other developers?

    As in the past, you have justified your claims by stating that the test you conducted was standard procedure at Kodak. Surely Kodak did not perform only this single extremely limited test on its developers. What other tests did Kodak conduct when assessing a developer, and how do Dektol and Tektol match up in those tests?

    Did you attempt to run any tests in which it was likely that Tektol or other Silvergrain products would show their superior qualities?
    Jon;

    First I would like to say that all commercial developers that I tested failed to equal Dektol. I have more to do in this ongoing series.

    Two other tests were used at Kodak, one of which did not apply and they were both much too expensive for me. However, they did verify the open tray test which I did use.

    Basically, in one of the tests, a 100 sheet box of 8x10 paper or thereabouts was flashed to Dmax over 30% of the area with a step wedge included on the edge. Sheets were equillibrated at room temperature for 1 day for latent image stabilization purposes, and then the sheets were processed one after another until the developer ceased to achieve a black dmax in the step wedge. Then the curves were plotted. (We used 35mm strips for film instead of 8x10 sheets for film developers.) We would often attempt to regain the original tone scale by developing longer. It works with Dektol, it did not with Tektol.

    This test gave results very close to the open tray 1 liter test which was ultimately used. The only difference, which was actually slight, was due to the halide salts seasoning the developer in one case, and not in the other. The drop in volume from the sheets being processed or evaporation was pretty similar for film and RC paper. FB paper caused a large drop in liquid level invalidating the test. The open tray test satisfied management and also the patent office.

    The other test, which does not apply, involved running 1000 ft rolls of paper in a continuous RT machine with replenishment. The paper was flashed to 30%, and had step wedges. The replenisher was formulated and reformulated to keep the step wedges constant. A formula had been derived for this iterative process. I never did this type of test, as I was not involved in formulating replenishers, only the start up tank or single use developers. It does not apply here.

    As I said earlier, Tektol performed as advertized when fresh. I tested only speed, contrast, image tone, dmax and dmin. I also measured pH. Tektol dropped in pH more rapidly than some developers, especially Dektol. As you can see in the pictures, Tektol is about a perfect match to the Dektol at 1:3 for 60" at 68F in all respects.

    PE

  5. #25
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    With reference to some questions I've had put to me or seen posted, ie, 'why would someone use this type of test?', I've thought that I should post an answer.

    In R&D, often one does not have a lot of a new chemical or coating. Due to expense, you may often have 10 grams or less of a new developing agent or stabilzer, or 10 feet or so of a 4.5" coating. Therefore, it is necessary for the research scientists involved to develop an economical method of testing coatings or chemicals. It helps if the test can be done quickly due to R&D time scales.

    Therefore, the test described above, the open tray keeping was developed to meet the needs of the R&D community with limited supplies of chemistry and/or coatings.

    So, the test above was designed to work with a minimum amount of developer and paper, and was verified to be a reliable benchmark. The length of the test was established to determine safety factor and recovery factor (the ability to adjust development time to get back what was lost by keeping) which was always paramount in Kodak's philosophy of design for developer capacity, fixer capacity or even coating expiration date.

    This is not meant to give you license to go overboard in pushing things, but there is the reasoning behind my testing methodology.

    PE

  6. #26

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    http://www.youtube.com/watch?v=ArDFVEikL8k

    There are two major places where you have to fight in the patent process. One is to fight with the examiners to prove they are wrong (if they are) and another is to litigate.

    The examiners are very tough but they don't always know what they are saying. Sometimes they make good judgment but not always. Sometimes you are SOL. What matters more is not just to have a good lawyer but also you (the inventor) become very familiar with the process of getting a patent.

    Anyway, in the case of Tektol developers, I had enough design parameters to avoid all those patents so I'd rather do that than spend money and time to fight. I'd be happier if they gave up some of the patents they are not using though.

    Another surprising thing is that there is a patent assigned to Kodak that names triethanolamine and salicylic acid (not as the main part of their claims but in the detailed description) that came way after I started using these compounds (as you can confirm online by searching my past postings elsewhere---this predates APUG). The patent has not much useful content and I'm not bothered by its offensive legal power, though.

  7. #27
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    Quote Originally Posted by Ryuji View Post
    How did you measure the tray life? Do you have rough estimate of how many milliliters of solution and how many square centimeters of air surface? Also, what was the average testing temp?
    No measurements involved. I'm simply reporting the results of my direct observations. No idea what the average temperature is other than the temperature has ranged between 65F and 70F.


    It is true that Tektol developers, especially Tektol neutral tends to take a bit more time to develop if you compare to Dektol stock or 1+1, but the reason why water bath technique doesn't work is primarily due to the difference in the developing agent. Hydroquinone is retained within the emulsion longer than ascorbate when the paper (or film in the case of film developer) is removed from the developer and immersed in plain water or alkaline bath. In my early days of experimenting with ascorbate, I also tried to make two-bath film develoeprs with ascorbate, but for this reason it does not work (well, I didn't know the reason at that time but now I do).
    Dektol doesn't work with a water bath either. When the waterbath doesn't work, one has to adjust developer dilution. The only developers I have used that do allow the water bath are amidol (best in this regard), PPPD, Agfa Neutol WA, and PF 130.


    True. I could make it to match the developing speed, but I thought it would be more important to make the neutral version (TND) really cold, solid black, and make it mixable with the standard version (TSD) so that people who want half cold developer can make it by simply mixing them.
    Nothing wrong with the difference in speeds. Its just an obvious difference that I note for the benefit of those who may be thinking of trying Tektol. Of the two, I actually liked the neutral version best for some unexplainable reason.

    Again, I'm curious to know how you compared TSD with 130...
    Again, nothing but direct observations of results obtained in my home darkroom. No strict controls of any kind. Water used is whatever comes out of the faucet. I do note the date whenever I mix something up as well as noting the date I open the stock solution container. I mixed my first bottle of PF 130 in January and used it through March. The only real reason I tossed it is because the original liter had diminished too much in volume from carryover to adequately cover the paper during development.
    Semper Fi & God Bless America
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  8. #28

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    Quote Originally Posted by Alex Hawley View Post
    No measurements involved. I'm simply reporting the results of my direct observations. No idea what the average temperature is other than the temperature has ranged between 65F and 70F.
    Ok- I was just curious to compare your test condition to mine.

    If you use larger air contact area per volume of developer, the developer will go off faster, of course. So this factor has to be held fixed for a fair test. Also, developers last longer if they are kept at a lower temperature. My tests are done at the ratio comparable to 600 square centimeters per liter of working solution (about the same as holding a liter of solution in an 8x10 tray) at 25C or 77F. I think my test condition is a good approximate to real life situation and if there is any error, my test is more difficult condition than real life due to slightly higher room temp.

    (In reality, the actual test situation is simpler than it may sound. I keep the developer solution in a beaker to the depth of 1.7cm, regardless of the beaker size.)

    Nothing wrong with the difference in speeds. Its just an obvious difference that I note for the benefit of those who may be thinking of trying Tektol.
    I don't think so either. If you prefer faster development, you could make the developer more concentrated. This would make the image tone even cooler. However, based on the feedback I get, more people actually prefer to dilute 1+14 for greater control and then use it as a single-session developer.

    Again, nothing but direct observations of results obtained in my home darkroom. No strict controls of any kind.
    Well, that is still a valuable feedback to me and it's also what counts ultimately. I do a lot of numerical calculations and chemical measurements in the early phase of developer development but in the last phases I'm making more fine changes by looking at test prints... Just like what vintners and whiskey distillers do.

    Thanks for your comments again.

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