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  1. #11
    gainer's Avatar
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    I'm still having difficulty seeing where the difference is between Mytol and PC-TEA with sulfite. Not that I don't believe there is a difference, because I have not tried both, and especially not in direct comparison. I'm just looking at formulas and seeing the same ingredients that can be made to be pretty close to one another by manipulations of dilution amount of sulfite. I guess I would truly be worried if either Jordan or I were making money off PC-TEA. The way I look at it, when I retired from NASA, I still work for the U.S. but I can do anything (legal) I want with my pension. In this case, I'm concerned about the mystery of it. I like explanations a whole lot better than mysteries, even though one thrives on the other.

    Now you can tell I'm getting old.
    Gadget Gainer

  2. #12
    fhovie's Avatar
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    I am not a chemist Pat, I do not know why some developing agents cause one effect and others something different. PC-TEA is marvelous at creating good densities and grain that stays completely sharp and seemingly large. When I use Mytol, the grains are not as large and there is a softening effect on the edges of them that help them blend. It is not as pronounced as the grain softening effect of D76 or D23. But it is certainly greater than PC-TEA - even with 60g/liter of sulfite added to it - which seemed to me to be ineffective at changing it in any way. Pat, I was so confident that PC-TEA would do what I wanted that I made a liter of stock solution, of which at least 800ml remains. The only reason I left Mytol in the first place was due to shelf life. When I mix it up and I use it 1:1 or 1:3 and then there is a month or more till I have the next run on roll film developing, I wind up with a confidence issue and dump it for fresh. I have no confidence issue with anything in glycol or TEA. Even my Pyrocat that I mix is exclusively done in glycol now because I started noticing a gradual decline in densities that necessitated a gradual increase in development times and a lot of negatives that were less dense than what I was shooting for. Another thing I noticed about PC-TEA is that it creates greater base fog in expired film than Mytol. I know this would likely be easily solved by adding some potassium bromide but I didn't follow this route because the grain issue has yet to be solved. I am comparing only negatives that are push processed as well. It might be that at N development, Mytol and PC-TEA are very close where at N+2, Mytol has less pronounced grain and PC-TEA has higher base fog. I have not experimented to see if adding not only the 60g/liter of sulfite but perhaps also 1g potassium bromide would make the results similar. With instant Mytol, that experiment would not be a priority for me right now but it would be nice to try some day. Curious that Mytol does not have bromide as a restrainer and yet has lower base fog, Maybe the big difference is that PC-TEA is more active in some ways and that causes it to give different results. Again, I am not a chemist - but I have been mixing a dozen or so different developers over the years and know that they all do things just a little bit different and that is why people adopt one and defend it - for properties that match their style. I wanted it to be PC-TEA and can not explain why it is not - but the appearance of the grain and the base fog are significantly different when push processed.
    My photos are always without all that distracting color ...

  3. #13
    gainer's Avatar
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    Looking at my original notes I find that I used a 50-50 mixture of TEA and Propylene glycol, and claimed 9.5 minutes at 70 F for TMY at 1:50 dilution.

    If you see base fog with PC-TEA that you do not see with Mytol, that certainly could explain the difference in grain, but not why the fog occurs in the first place. It might be that a little benzotriazole would help. You could used bromide in the working solution, but I have read that it is not very effective in phenidone developers.

    The problem with the internet is the difficulty of showing such things as grain and resolution, especially when my maximum transmission rate here in the boondocks is 26.4 K. Some day we'll be able to get DSL. I hope I'm still alive to celebrate it. I can't afford a satellite hookup. Maybe if I enlarge the heck out of a piece I can show what I find. Scanning in general is a little iffy because of aliasing between scan rate and grain size.
    Gadget Gainer

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