PC TEA - The new frontier?

Discussion in 'B&W: Film, Paper, Chemistry' started by fhovie, Dec 14, 2004.

  1. fhovie

    fhovie Subscriber

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    I was delighted with the performance of my home-made XTOL (MYTOL) - but not delighted with the same old D76 deterioration on the shelf and the mixing of large stock solutions with limited capacity. So I just tried PC-TEA hoping to get the same performance I was getting with MYTOL but with the convenience of a 50:1 stock solution with unlimited shelf life. My first try using
    400ml TEA at 250 F
    45g Ascorbic Acid
    1.25g Phenidone
    last 100ml TEA
    50:1 at 68 F
    was TRI-X pushed to 1600. 14 minutes with 5 sec agitation every 30 sec.
    All my shadow detail is there and the film looks great - I will soon know if the grain is tight and by looking at it, it doesn't seem to have that N+2 look I was expecting and half hoping for - I may try a three stop push if it doesn't have the contrast expansion I was looking for. (Dusk shots with very low contrast)

    Should I add Benzotriazole or Potassium Bromide? I don't seem to have any streaking or fogging now but I will certainly be using this for FP4 (if it can be purchased ... ) and other films as well. I am also hoping the grain will be as fine as the MYTOL I was using - (which had some sulfite in it) I would like microdol fineness with acufine speed ... with pyro accutance - throw in the moon and stars and I will not have to experiment for at least a few weeks!

    Any advise from the pros would be very appreciated!
     
  2. gainer

    gainer Subscriber

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    I don't use restrainer, but then I can stand a little base fog. 35 mm HP5+ has a base density of about 0.2 even when you remove the emulsion. neither benzotriazole nor potassium bromide can do anything about that part of the fog. I don't think the sheet film has that in the base, the antihalation being provided by a dye in the gelatin coating on the back of the film which washes out in the processing. You will just have to try it for yourself unless someone else chimes in. It is easilly added to the concentrate or to the working solution. I do keep a saturated solution of KBr handy, a few drops of which does the job on paper. Do a test without restrainer for your personal satisfaction.
     
  3. arigram

    arigram Member

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    You are welcome to throw at me any curse words in the book, but I want to ask:
    - What the hell is PC-TEA?
    I keep reading about it a lot in APUG but apart from being a film developer, I don't know anything else about it! It is just home made or can be found ready?
    Anyone kind enough to enlighten this cave-dweller?
     
  4. gainer

    gainer Subscriber

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    TEA is short for triethanolamine, an organic liquid solvent and base. It will dissolve most of our developing agents to an extent useful in making concentrated stock solutions. It does not become basic until water is added.

    PC-TEA as used here is:

    100 ml TEA
    9 g ascorbic acid (erytorbic acid, AKA isoascorbic acid works as well)
    2.25 g phenidone

    Heat this mixture to about 160 F and stir till it dissolves. It will stay dissolved after it cools. If it gets a brown color, don't be worried. TEA by itself turns brown upon sufficient heating. At 160, it shouldn't be any darker than HC110 concentrate.

    This concentrate is diluted 1+25 or 1+50 for use on film. I don't want to brag too much, but it's pretty good stuff. Note that there is no sulfite. If you think there should be, add it to the working solution, but try it without sulfite first.
     
  5. gainer

    gainer Subscriber

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    I put the decimal in the wrong place. It should be 0.225 grams of phenidone.
     
  6. sanking

    sanking Restricted Access

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    As an alternative printer I abhor any type of B+F that is in excess of the theoretical minimum. When one processes fresh FP4+ (or Delta 100 or Tmax-100) sheet film in developers such as D76, Xtol or Pyrocat-HD the B+F is about log 0.06. Processed in PC-TEA with no restrainer the B+F is around 0.20. This amount to almost 1/2 of a stop loss in printing speed, which can amount to a very long time when printing with a UV sensitive alternative process where printing times are in the minutes or tens of minutes.

    I did some tests with PC-TEA in an effort to reduce B+F without loss of activity or energy level. What I found was that adding 0.2g of potassium bromide per 100ml of stock solution of PC-TEA reduces B+F of the films mentioned above to about log 0.08, without reducing the activity of the developer. The exact amount is very critical because more bromide will result in loss of energy while less leaves you with a high B+F. I add the bromide directly to the stock solution when mixing, after the ascorbic acid goes in but before the phenidone.

    Sandy
     
  7. Quinine

    Quinine Member

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    TEA

    TEA = TriEthanolAmin

    what i really hate about it is the high viscosity of TEA/the concentrate.

    best regards, --- jan.
     
  8. Flotsam

    Flotsam Member

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    You should probably edit that in the original post. If someone just searches apug or google on PC TEA they might just see the errant formula and ruin some film and waste some chems.
     
  9. fhovie

    fhovie Subscriber

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    That is exactly what I was looking for - Thanks!!
     
  10. arigram

    arigram Member

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    So, what is PC-TEA good for?
     
  11. sanking

    sanking Restricted Access

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    It is used for developing film.

    Sandy
     
  12. gainer

    gainer Subscriber

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    Bravo! It's about time someone told the truth.
     
  13. Flotsam

    Flotsam Member

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    You mean that you're not supposed to drink it with Lemon and Sugar?! :surprised: Ptoooi!!!
     
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  15. gainer

    gainer Subscriber

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    The original post was in Photo Techniques Magazine under the title "The Role of Antifreeze in the Photographic Process"

    You might use more phenidone than necessary, but I don't think you would ruin much film. There is a ratio of ascorbic acid to phenidone that is optimum but if you hold ascorbic acid constant and increase phenidone, the curve of contrast index vs phenidone content will flatten out. I did test the other way round, holding phenidone constant.

    I will test the erroneous formula to see if it does ruin film. If your own test seems to show too much phenidone, you can dilute the stock with more of everything else: more TEA and more ascorbic acid.
     
  16. Daniel Grenier

    Daniel Grenier Member

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    I am unclear as to the advantages of this formulation over, say, Pyrocat (which is what I use now). What is there to gain,besides increased activity, in a switch to PC-TEA? Am I missing something???
     
  17. Flotsam

    Flotsam Member

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    I have no clue what effect using the formula with the misplaced decimal point would have on the film. I'm strictly a recipe follower. I only mentioned it because when I became interested in your formula, I just searched on the name and found it on APUG. Without a basic knowledge of photo chemistry, I would have followed the formula unquestioningly to the letter even if it had mistakenly called for a cup of Chicken broth :smile:. I just thought that correcting the the formula in the might help avoid confusion among recipe followers like myself.
     
  18. john_s

    john_s Member

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    Would the addition of bromide increase edge effects? On the grounds of decreased activity of the developer near dense areas?
     
  19. sanking

    sanking Restricted Access

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    Actually, Pyrocat-HD, even with the 1:1:100 dilution, is a more active developer than PC-TEA. And, at least from my own comparisions, Pyrocat-HD (because of grain masking) gives slightly finer grain than PC-TEA. Both give very high acutance, though the physical method of development matters a lot when maximum acutance is the issue, and in many cases is more important than the developer itself.

    PC-TEA has a convenience factor in that it is a one-solution developer. Like Rodinal, you just dilute it with water. And it gives much finer grain than Rodinal.

    Pyrocat-HD is my developer of choice for most applications, but there are times when a non-staining developer may be desired, and at those times, voila PC-TEA. Much cheaper than Rodinal, and better results. Unless of course you like the golf-ball size grain of Rodinal.

    Sandy
     
    Last edited by a moderator: Dec 15, 2004
  20. fhovie

    fhovie Subscriber

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    PC TEA also gives full film speed - which is one advantage over pyro - especially for push processing - I am not sure the grain of PyrocatHD is smaller that PC-TEA. I am certain that XTOL is finer - it contains sulfite though. - which means there is a trade (PC-TEA and XTOL) - some sharpness for some finer grain. Not a big trade in this case though. I use pyrocat exclusively for LF with no regrets - I am not always happy with bigger enlargments on roll film in pyro - at least Pyrocat is a lot finer than PMK.
     
  21. sanking

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    The issue of shelf life of Pyrocat-HD (or of PMK or Rollo Pyro for that matter) versus a developer such as PC-TEA is really a non-issue. The simple fact is that the Stock A solutions of Pyrocat-HD, PMK and Rollo Pyro can be mixed in propylene glycol with a resulting shelf life as long as that of PC-TEA, or any of the -TEA developers. And there is no need to be concerned about the shelf life of the Stock B solutions of these developers because it is on the order of years and years. Moreover, both PMK, Pyrocat-HD and Rollo Pyro can be mixed in TEA if desired, without the necessity of a Stock B solution, giving the same single solution advantages of PC-TEA.

    However, there are some important reasons why one might choose a staining developer over a non-staining developer. The issue is fairly complex and persons interested in more detail might have a look at my article on pyro staining developers at http://unblinkingeye.com/Articles/PCat/pcat.html.

    Sandy
     
  22. gainer

    gainer Subscriber

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    You need not defend yourself for your sugestion of editing. It gave me a good chance to see what would happen. I did the test first with the recipe as it should have been, on HP5+ 35 mm, as per my usual ploy of exposing a whole roll to the same scene. In this case it was a step density wedge. Then I added enough phenidone in glycol to bring the total to 10 times the original amount and repeated development of a strip from the same roll.

    I was unable to identify one strip from the other either visually or by scanning and displaying them side by side. When I am fully awake I will make a side by side contact print.

    Some of you will be surprised, I'm sure, that 10 times the amount of phenidone made no significant difference in the negatives. As long as you keep the ascorbic acid constant and the phenidone at least a fortieth of that amount, there will be neither advantage nor disadvantage to increasing the phenidone.
     
  23. Maine-iac

    Maine-iac Member

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    I mixed up some PC-TEA following directions I got from somewhere in this forum awhile ago. I heated it to 250 and while everything mixed up OK, it turned a very dark brown in color (like black coffee almost) and smells horrible, even now when I dilute it for developing. It works perfectly well as announced, and gives me good negs, but about drives me out of the darkroom with the odor.

    Is this characteristic? If so, I'll go back to my TEA-less existence. Is it the result of over-heating (I notice that Gainer's post mentions heating it to 160 degrees.)? Not only is the smell bad, but it persists in the darkroom for a day or more.

    Larry
     
  24. gainer

    gainer Subscriber

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    I guess I created a monster. A long dead one at that. I think it does not stink so badly when it is made at the lower temoerature. I know it is not nearly so dark. That color is due to the fact that TEA darkens with heating.

    You might like it better as an A-B stock with the A being same as PC-TEA but using propylene glycol as the solvent. You may then use TEA as the B or you may use the B part of PMK or you may experiment with various amounts of sodium carbonate. Nicholas Twist uses a teaspoon each of sodium carbonate and sodium bicarbonate to the liter.

    In either TEA or glycol the life of the A solution is very long.
     
  25. psvensson

    psvensson Member

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    Yup, I'm surprised. This weekend I tried a PC-TEA version with 8 times the recommended amount of phenidone on Delta 400, and it reduced activity by 30%. That surprised me too. I'm guessing it has to do with the reaction products of phenidone inhibiting development.
     
  26. gainer

    gainer Subscriber

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    I did make the contact sheet comparing the two phenidone concentrations side by each, and the biggest difference I could make out was a slight increase in base fog with the increased phenidone. What else was in your developer?