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  1. #21

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    hi,

    i've experimented with sod. carbonate as a B bath and it seems that it doesn't have the pH required to complete development. it does develop some of the image but the contrast was too low and the stain was not as visible as it is with sod. hydroxide.

  2. #22
    patrickjames's Avatar
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    Quote Originally Posted by el wacho View Post
    hi,

    i've experimented with sod. carbonate as a B bath and it seems that it doesn't have the pH required to complete development. it does develop some of the image but the contrast was too low and the stain was not as visible as it is with sod. hydroxide.
    What is your dilution (normal/two part) with the hydroxide?

  3. #23
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    Quote Originally Posted by el wacho View Post
    hi,

    i've experimented with sod. carbonate as a B bath and it seems that it doesn't have the pH required to complete development. it does develop some of the image but the contrast was too low and the stain was not as visible as it is with sod. hydroxide.
    That is an interesting observation. I am assuming you increased the amount of concentrate by 5 as recommended by Sandy King in his article on www.unblikingeye.com . According to that article the both Sodium and Potassium Carbonate perform in exactly the same way except that you need 5 time more working solution because only 200g is diluted with a litre of water as opposed to 750g of potassium carbonate. Of course, sodium hydroxide is more energetic than either of the carbonates.

    My first foray with Pyrocat was a complete disaster. The negative came out dreadfully thin although there was a very obvious stain. I have written up a series of tests ranging from a badly performing shutter (since disproven) to bad chemistry. My chief suspect is the bath B because the sodium carbonate I used was very old (in excess of 10 years). The chances are that it must have absorbed some moisture from the air in that time as it was in a screw top jar rather than a sealed tub. I suspect it is nowhere near as potent as it was when it was fresh.

  4. #24

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    Patrick - at the moment i've settled on 1:1:200 using sod. hydroxide 100gr/L

    Adrian - yes five times was recommend as i understand for single bath usage as a possible replacement for pot carbonate but not taking into consideration the two bath usage. a B bath at the recommended 1:10 of the 200gr/L solution would be about 20g/L. i knew straight away that wouldnt work because catechol needs the higher pH (just look at some old catechol formulas like pextrals two bath) so i bumped it up to 35gr/500ml and still got a very soft image. it confirmed in my mind that there was a reason the old formulas were using sod hydroxide for a reason, that being of the working pH. where it gets really interesting is where you lower the level of sod hydroxide enough so that the bromides released during development in the highlights do actually start to buffer. at this point lower dilutions start to respond to agitation variations a little more apparently on the print.
    Last edited by el wacho; 09-19-2010 at 05:50 PM. Click to view previous post history. Reason: clarity

  5. #25
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    To take this astray, I needed to make new MC after about a year and a half. I used the Metol slurry last time but read Sandy's alternate advice about heating the Glycol to 250 degrees and decided to do that. Everyting dropped into solution almost instantly, just great!!! Thank you, Sandy...EC

  6. #26

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    just found this which i thought was relevant...

    pH of 1% sodium hydroxide is 12.7:
    http:http://www.pacia.org.au/_uploaditems..._hydroxide.pdf
    pH of 10% sodium carbonate is 11.7:
    http://www.intox.org/databank/docume...carb/cie20.htm

    thanks to Alan Johnson for this post.

  7. #27

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    Quote Originally Posted by eclarke View Post
    To take this astray, I needed to make new MC after about a year and a half. I used the Metol slurry last time but read Sandy's alternate advice about heating the Glycol to 250 degrees and decided to do that. Everyting dropped into solution almost instantly, just great!!! Thank you, Sandy...EC

    Glad it worked, and thanks for mentioning it. I have not mixed any MC in quite a while and actually forgot about my suggestion to heat the Glcyol up to 250F.

    Just be sure to be very careful working with Glycol that hot as it could do a lot of damage if you were to drop it on any body part.

    Sandy

  8. #28

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    I was wondering why the presoak is needed with the Divided Pyrocat-HD development? All over the APUG threads about divided development it is said that presoak shoud be avoid so that the emulsion should soak the developing agent, not the plain water. Can anyone tell, what is the practical reason of using presoak with Divided Pyrocat-HD?

  9. #29
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    Another question; A few drops of Photo Flo is used in part A and not part B, correct? Can LFN be substituted for Photo Flo?
    Everytime I find a film or paper that I like, they discontinue it. - Paul Strand - Aperture monograph on Strand

  10. #30

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    The presoak allows the gelatin of the emulsion to swell a little so the A bath can be more easily and evenly absorbed. At least that's the theory. Films like Acros and TMX have chemically hardened emulsions designed to withstand the high temperatures of machine development. A presoak allows them to loosen up a little.

    Yes, the Photo Flo goes into part A. It allows the solution to drain off more easily before placing it in the B solution. Allow the film coming out of part A 15 seconds to drain before placing into B, and agitate vigorously in the B for the first minute.

    Peter Gomena

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