Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 71,954   Posts: 1,586,010   Online: 674
      
Page 3 of 5 FirstFirst 12345 LastLast
Results 21 to 30 of 50
  1. #21

    Join Date
    Jan 2006
    Location
    Portland, ME
    Shooter
    35mm RF
    Posts
    11
    Quote Originally Posted by srs5694
    You basically ended up with a conventional phenidone/vitamin C (PC) developer plus coffee. You might want to consider E-72 instead; it's fairly simple (five ingredients, including water) and it's lasted me through multi-hour sessions. I've also used DS-14 with good results. It's more complex, though.
    Thanks. I'll check out the E76. I thought sodium sulfite was toxic so I was avoiding it.

  2. #22

    Join Date
    May 2005
    Location
    Woonsocket, RI USA
    Shooter
    35mm
    Posts
    2,725
    Quote Originally Posted by nspatel
    Quote Originally Posted by srs5694
    You might want to consider E-72 instead
    Thanks. I'll check out the E76. I thought sodium sulfite was toxic so I was avoiding it.
    E-76 is a PC variant of D-76, the film developer; E-72 is a PC variant of D-72/Dektol, the paper developer.

    As to toxicity, I'm far from an expert, but my understanding is that sodium sulfite isn't a big risk compared to other chemicals you're likely to have in your darkroom. It's hard for a non-expert to evaluate this, though, since MSDS sheets and whatnot are typically so thorough that they make the most innocuous substance sound like it's a life-threatening toxin. (For instance, check out this MSDS sheet for water.)

  3. #23

    Join Date
    Dec 2004
    Shooter
    Multi Format
    Posts
    1,670
    Sodium sulfite is not dangerous in small quantities except to certain asthmatics whose conditions are aggrevated by it. It is used to preserve wine and certain foods.

  4. #24
    titrisol's Avatar
    Join Date
    Aug 2004
    Location
    Rotterdam
    Shooter
    Multi Format
    Posts
    1,671
    Images
    8
    Water? you mean hydrogen hydroxide?
    Or dihydrogen oxide?
    Mama took my APX away.....

  5. #25
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,561
    Images
    65
    The original URLs posted by Titrisol of the work done at RIT refers to recent work.

    This entire subject has been known about 100 years, and is reported on in the Haist Book, "Modern Photographic Processing" and has also been mentioned in Anchell and Troop.

    PE

  6. #26

    Join Date
    Jan 2006
    Location
    Portland, ME
    Shooter
    35mm RF
    Posts
    11
    Quote Originally Posted by Photo Engineer
    The original URLs posted by Titrisol of the work done at RIT refers to recent work.

    This entire subject has been known about 100 years, and is reported on in the Haist Book, "Modern Photographic Processing" and has also been mentioned in Anchell and Troop.

    PE

    I checked out the original urls in the Titrisol's posts and it was everything that I had read before I started experimenting. I will have check out the Haist book though.

    Basically what I was trying to do was utilize the coffee with develop times that were more reasonable. Adding the Ascorbic Acid and Phendione definately helped, but it makes me wonder if there is any merit to mixing develop agents that are not superadditive. I guess there are comercial developers do this to some extent. It seems like mixing a low contrast and a medium or high constrast developer would be beneficial but it is likely that the faster acting developer will dominate the reduction process. Especially if each of the develop agents respond differently to temperature.

    Right now I am working on splitting out the developers into 2 baths to try to utilize the benefits of each(although at the cost of small develop times). One bath uses just coffee as the develop agent and the other just uses the ascorbic acid/phenidone combo with less alkali to make it less aggressive.
    The idea is that the coffee will render the bulk of the image without the full density. The ascorbic acid/phenidone will just bring the density up in the darker areas to get more blacks. The limited work I have done so far seems to show this behavior but I don't think I have enough data yet.

  7. #27
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,561
    Images
    65
    Quote Originally Posted by nspatel
    I checked out the original urls in the Titrisol's posts and it was everything that I had read before I started experimenting. I will have check out the Haist book though.

    Basically what I was trying to do was utilize the coffee with develop times that were more reasonable. Adding the Ascorbic Acid and Phendione definately helped, but it makes me wonder if there is any merit to mixing develop agents that are not superadditive. I guess there are comercial developers do this to some extent. It seems like mixing a low contrast and a medium or high constrast developer would be beneficial but it is likely that the faster acting developer will dominate the reduction process. Especially if each of the develop agents respond differently to temperature.

    Right now I am working on splitting out the developers into 2 baths to try to utilize the benefits of each(although at the cost of small develop times). One bath uses just coffee as the develop agent and the other just uses the ascorbic acid/phenidone combo with less alkali to make it less aggressive.
    The idea is that the coffee will render the bulk of the image without the full density. The ascorbic acid/phenidone will just bring the density up in the darker areas to get more blacks. The limited work I have done so far seems to show this behavior but I don't think I have enough data yet.
    When you mix developing agents and see a big boost in activity, you never know what went on. Was it a superadditive effect or was it just the new developing agent being more active.

    When you add an auxiliary developing agent to one of the coffee based developers, often the auxiliary developing agent takes over as the primary developing agent and you don't realize it unless you do lots of check experiments.

    This is a very chancy thing to do and claim this or that mixture works. It may be that you could get along with another mixture as well or better. I think that you are very wise to say you don't have enough data yet. Keep at it though, there is a lot to discover out there.

    PE

  8. #28

    Join Date
    Jan 2006
    Location
    Portland, ME
    Shooter
    35mm RF
    Posts
    11
    Quote Originally Posted by Photo Engineer
    When you mix developing agents and see a big boost in activity, you never know what went on. Was it a superadditive effect or was it just the new developing agent being more active.

    When you add an auxiliary developing agent to one of the coffee based developers, often the auxiliary developing agent takes over as the primary developing agent and you don't realize it unless you do lots of check experiments.

    This is a very chancy thing to do and claim this or that mixture works. It may be that you could get along with another mixture as well or better. I think that you are very wise to say you don't have enough data yet. Keep at it though, there is a lot to discover out there.

    PE

    My bosses at work do a fine job at concluding things with too little data.

    Would you know where I could could find good reading on superadditivity? My internet searches have not been so fruitful. I am looking for a semi-technical to technical explanation of what is going on.

  9. #29
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,561
    Images
    65
    Quote Originally Posted by nspatel
    My bosses at work do a fine job at concluding things with too little data.

    Would you know where I could could find good reading on superadditivity? My internet searches have not been so fruitful. I am looking for a semi-technical to technical explanation of what is going on.
    I'll suggest two authors with good work on the subject.

    Mees and James "Theory of the Photographic Process"

    Haist "Modern Photographic Processes" (2 volumes)

    I think I got them both right.

    PE

  10. #30

    Join Date
    Jan 2006
    Location
    Portland, ME
    Shooter
    35mm RF
    Posts
    11
    Quote Originally Posted by Photo Engineer
    I'll suggest two authors with good work on the subject.

    Mees and James "Theory of the Photographic Process"

    Haist "Modern Photographic Processes" (2 volumes)

    I think I got them both right.

    PE
    PE,

    Thanks for the info. I apprieciate it. I noticed you are located in Rochester. Incidentally, I got my degree at R.I.T. Unfortunately, it was not in photography though.

    -nsp

Page 3 of 5 FirstFirst 12345 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin