Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 69,954   Posts: 1,522,781   Online: 969
      
Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 30
  1. #11

    Join Date
    Nov 2004
    Posts
    1,121
    In FX-55 the phenidone is added with the ascorbate.
    If it was wished to use spoon measures the powders would probably have to be mixed together first.

  2. #12
    jp498's Avatar
    Join Date
    Oct 2009
    Location
    Owls Head ME
    Shooter
    Multi Format
    Posts
    1,449
    Images
    74
    I'd be happy with shoveling in ascorbic acid, liquid concentrate (I have cheap pipettes for that), or how about "sugar packs" or tablets of the stuff.

  3. #13

    Join Date
    Jul 2010
    Location
    Southern USA
    Shooter
    Multi Format
    Posts
    3,769
    The use of ascorbic acid in the food industry is wide spread. Why, because it readily scavenges oxtgen and therefore protects other chemicals. Because of this it is unstable in solution so making up a concentrate solution is really of no help. As has been stated over and over again on APUG the main problem is Fenton oxidation which is catalysed by iron and copper in the chemicals themselves and in the water used to make up solutions. Use only de-ionized water for making up solutions. Do not use distilled water as this is often made using copper equipment. The stabilitry of ascorbates is improved with the use of certain chelating agents such as salicylic acid and TEA.

    My suggestions would be either to mix up the developer without the ascorbate and then weigh it just before use

    OR

    use the two chelating agents mentioned and use only de-ionized water.
    Last edited by Gerald C Koch; 03-28-2013 at 09:47 AM. Click to view previous post history.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

  4. #14

    Join Date
    Apr 2008
    Location
    Escondido, California, USA
    Shooter
    35mm RF
    Posts
    653
    Quote Originally Posted by Gerald C Koch View Post
    My suggestions would be either to mix up the developer without the ascorbate and then weigh it just before use
    OR
    use the two chelating agents mentioned and use only de-ionized water.
    Quote Originally Posted by Alan Johnson View Post
    What evidence is there that the phenidone and sulfite part of the developer would be long lasting?The question is based on an unproven assumption.
    Alan and Jerry quickly perceived my evil plans.

    In ascorbate developers, the ascorbate typically is destroyed first (by Mr. Fenton), so my idea is to add it separately. But as Alan points out, the sulfite and Phenidone might not last long either. PE has said that Dimezone S is more resistant to hydrolysis than Phenidone, and we know it lasts for over 6 months in capped bottles of XTOL. Sulfite is oxidized by air, changing it to useless sulfate, but my calculation of air-moles versus liquid-moles says this won't be a problem in typical usage. So maybe, just maybe sulfite+Dimezone will last long. Only testing will prove that, and I wanted to know if this add-C-separately idea appealed to people before doing that testing. Hence my posting.

    jp498 suggested tablets. That's a good idea: Vitamin C pills are widely available in 250, 500 and 1000 mg sizes. That would solve the measurement problem. Hmmm...

    Mark Overton

  5. #15

    Join Date
    Feb 2010
    Location
    Montreal, Canada
    Shooter
    Multi Format
    Posts
    4,537
    I'm confused about the Phenidone/Sulfite part. Would this be mixed in a solvent like TEA that does not readily transfer Oxygen? Otherwise wouldn't a Phenidone-Sulfite-Water solution be pretty short-lived/unstable? I'm thinking of POTA for example.

  6. #16

    Join Date
    Apr 2008
    Location
    Escondido, California, USA
    Shooter
    35mm RF
    Posts
    653
    Quote Originally Posted by Michael R 1974 View Post
    I'm confused about the Phenidone/Sulfite part. Would this be mixed in a solvent like TEA that does not readily transfer Oxygen? Otherwise wouldn't a Phenidone-Sulfite-Water solution be pretty short-lived/unstable? I'm thinking of POTA for example.
    Yes, this would be water-based ready-to-use developer like D-76 or XTOL, except that some Vitamin C would be added just before use. And Phenidone is subject to hydrolysis, so I'm hoping that Dimezone S will last longer.

    Mark

  7. #17

    Join Date
    Nov 2004
    Posts
    1,121
    Here I can buy a 120w 6-speed hand held mixer for GBP 8.
    The ascorbic acid and phenidone could be mixed together then measured out with a spoon?
    On second thoughts that's a bit industrial and not safe for amateur work.
    Last edited by Alan Johnson; 03-29-2013 at 02:07 PM. Click to view previous post history.

  8. #18
    Zathras's Avatar
    Join Date
    Nov 2004
    Location
    SF Bay Area
    Shooter
    Multi Format
    Posts
    504
    Since I prefer Metol to Phenidone, I've been playing with the idea of using D23 as a sort of stock solution since the required amount of Metol is only .2 grams per liter of Gainer's formula. I plan to make the working solution by starting with 900ml of water, adding 2.0 grams of ascorbic acid, 26.6ml of D23 and 6.0 grams of sodium metaborate, in the form of PMK "B" solution and topping it up to 1.0 liter. I figure that the 100 grams of sodium sulfite in the D23 should preserve the Metol for at least 2 months if stored properly.

    I'm basing my idea on Pat Gainer's Vitamin C developers, but trying to eliminate errors in weighing out small quantities of Metol every time. Since I do use D23, I thought that it might make a good stock solution for the Metol, and if I don't like the results from Gainer's developer, I still have D23.

    When diluted, there will be less than 3.0 grams of sulfite in the developer compared with none according to Pat's formula. I don't know if that would make a big difference or not, so I'll need to test carefully. When I have the chance, I'll run some BTZS tests with a couple of films and see what happens.

    Since I'm not trying to make a developer that works like Xtol this may not be what the OP has in mind. I was just considering an alternative.
    When the chips are down,

    The buffalo is empty!!!



  9. #19

    Join Date
    Feb 2010
    Location
    Montreal, Canada
    Shooter
    Multi Format
    Posts
    4,537
    Quote Originally Posted by Gerald C Koch View Post
    The use of ascorbic acid in the food industry is wide spread. Why, because it readily scavenges oxtgen and therefore protects other chemicals. Because of this it is unstable in solution so making up a concentrate solution is really of no help. As has been stated over and over again on APUG the main problem is Fenton oxidation which is catalysed by iron and copper in the chemicals themselves and in the water used to make up solutions. Use only de-ionized water for making up solutions. Do not use distilled water as this is often made using copper equipment. The stabilitry of ascorbates is improved with the use of certain chelating agents such as salicylic acid and TEA.

    My suggestions would be either to mix up the developer without the ascorbate and then weigh it just before use

    OR

    use the two chelating agents mentioned and use only de-ionized water.
    Gerald, what is the difference between distilled, deionized, or distilled and deionized, or "equivalent to distilled" - presumably by reverse osmosis? I have always used distilled water, but now I'm wondering if perhaps rather than improving things vs tap water, my distilled water is the reason my XTOL always seems somewhat "weak" even when freshly mixed. Is that possible, of would Fenton oxidation only take place over time with storage. I'm confused about water.

  10. #20

    Join Date
    Jul 2010
    Location
    Southern USA
    Shooter
    Multi Format
    Posts
    3,769
    There are 3 ways to eliminate impurities in water

    1, Distillation, the oldest method. Water is vaporized, leaving the impurities behind, then allowed to cool using a condenser to form liquid water again. Traditionally a copper condensor was used for its large heat transfer capabilrty. If a metal condensor or catch container is made of metal then the water may become contaminated with metal ions. A particular problem is with copper. Even ordinary glas is a problem in preparing water for conductivity experimnts. The sodium in ordinary glass leachs out. Only fused silica equipment can be used.

    2 De-ionization, the water is passed throught a mixed resin ion exchange column. Metal ions are replaced with hydrogen ions and anions with hydroxide ions. The hydrogen and hydroxide ions combin to form water.

    3 Reverse osmosis, water under great pressure is forced through a semipermeable barrier. Large ions cannot pass through leaving, in theory, pure water.

    Iron and copper are common contaminants of the chemicals used for making developers. The wrorst offenders are probably sodium sulfite and sodium carbonate. So just using purified water may not help. A chelating agent is the best way to insure the storage life of ascorbate developers. Salicylic acid chelates iron and TEA does the same for copper.

    With the right amount of iron III all the ascorbate in a solution can be destroyed in an hour or so. It can be that fast.
    Last edited by Gerald C Koch; 03-29-2013 at 10:34 PM. Click to view previous post history.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

Page 2 of 3 FirstFirst 123 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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