Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 68,688   Posts: 1,482,361   Online: 760
      
Page 4 of 7 FirstFirst 1234567 LastLast
Results 31 to 40 of 61
  1. #31

    Join Date
    Jul 2006
    Location
    Oklahoma, USA
    Shooter
    Med. Format RF
    Posts
    670
    Quote Originally Posted by sepiareverb View Post
    Moersch ECO 4812 is my choice. Lasts a startlingly long time as a working solution in a bottle.
    Liquidol and ECO 4812 meet your criteria.
    RJ

  2. #32

    Join Date
    Jan 2008
    Location
    Sarasota, FL
    Shooter
    35mm
    Posts
    921
    Quote Originally Posted by Rudeofus View Post
    Paul, Phenidone is known to be unstable in alkaline environment so your ID-67 formula would be quite unsuitable for long shelf life. Replace the Phenidone with twice the amount of Dimezone S if you want longer shelf life.
    I rather doubt that phenidone is unstable in the alkaline developer environment. Maybe less stable than Dimezone, but not unstable. I rather doubt Ilford and other companies would have spent years making and marketing phenidone/HQ developers if this matter was of concern. Nor has this been any kind of problem in my own mixes and use.

  3. #33

    Join Date
    Feb 2010
    Location
    Montreal, Canada
    Shooter
    Multi Format
    Posts
    4,258
    It may depend on the composition of the complete formula, concentrations, how much preservative etc but on its own yes Phenidone is apparently unstable. POTA is just Phenidone and Sodium Sulfite and is quite short lived.

  4. #34
    Ian Grant's Avatar
    Join Date
    Aug 2004
    Location
    West Midlands, UK, and Turkey
    Shooter
    Multi Format
    Posts
    15,943
    Images
    148
    Quote Originally Posted by Rudeofus View Post
    Paul, Phenidone is known to be unstable in alkaline environment so your ID-67 formula would be quite unsuitable for long shelf life. Replace the Phenidone with twice the amount of Dimezone S if you want longer shelf life.
    Much of that seems to be hype from a US competitor because in practice the form of phenidone used in Ilford commercial developers is/was stable, some now use Dimezone since manufacture was sub-contracted.

    Some books claim Phenidone has a poor shelf life (as a raw chemical) but I was using Phenidone made in 1962 until my supply ran out 4-5 years ago and it was just as good as my newer supplies. It's often forgotten that Phenidone is a Trade name and there's a number of variants, there were issues with the original form of Phenidone but by the time Ilford marketd Phenidone based devlopers these had been overcome.

    In practice the ID-78 I make up lasts well over 2 years in a good plastic bottle, it's the warm tone variant of ID-62, but shelf lifes no different to ID-67.

    Ian

  5. #35

    Join Date
    Jan 2008
    Location
    Sarasota, FL
    Shooter
    35mm
    Posts
    921
    Quote Originally Posted by Michael R 1974 View Post
    It may depend on the composition of the complete formula, concentrations, how much preservative etc but on its own yes Phenidone is apparently unstable. POTA is just Phenidone and Sodium Sulfite and is quite short lived.

    Probably because POTA has no hydroquinone which is regenerative of either metol or phenidone.

    I think Ian Grant, below, explains it all well.

    Regardless, as to the situation of the OP, FREEZE IT!

  6. #36

    Join Date
    Jul 2006
    Location
    Oklahoma, USA
    Shooter
    Med. Format RF
    Posts
    670
    130 is a nice developer but it changes in tray with usage, is expensive, and dislikes temps below 21c.
    RJ

  7. #37
    Thomas Bertilsson's Avatar
    Join Date
    Jan 2003
    Location
    Minnesota
    Shooter
    Multi Format
    Posts
    13,985
    Images
    279
    Actual keeping properties of Ethol LPD I don't know about, but I've had it last for 6+ months, (when I had no darkroom access), at 2+1 dilution in a partially filled brown amber glass bottle. I doubt it would last two years even as a concentrate.
    Ethol themselves claim that LPD lasts for six months. I normally use it up before six months passes by so I have no way of verifying working solution or stock solution, only 2:1 mix with water.
    "Often moments come looking for us". - Robert Frank

    "Make good art!" - Neil Gaiman

    "...the heart and mind are the true lens of the camera". - Yousuf Karsh

  8. #38
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    22,710
    Images
    65
    Phenidone is a chemical called a hydrazone. Hydrazones in general will hydrolyze in alkali back into their parts. Since phenidone is a ring compound it merely ring opens and becomes inactive. Dimezone and Dimezone-S have blocking groups at the site of hydrolysis and are therefore far more stable in alkali than the parent phenidone.

    I know, I know, you all hate organic chemistry. Go ahead and use phenidone developers. They will last - a while, and then organic chemistry will bite you on the butt just when you least expect it.

    PE
    Last edited by Photo Engineer; 01-08-2013 at 01:39 PM. Click to view previous post history.

  9. #39

    Join Date
    Feb 2010
    Location
    Montreal, Canada
    Shooter
    Multi Format
    Posts
    4,258
    I for one do not hate organic chemistry, and appreciate the explanation. I think this is quite important as I doubt many are fully aware of the differences between Phenidone and its Dimezone derivatives. We sort of know Dimezone is "better" than Phenidone, but specifics are helpful. I think there was some good discussion about this in Mark Overton's XTOL clone thread.

  10. #40
    Ian Grant's Avatar
    Join Date
    Aug 2004
    Location
    West Midlands, UK, and Turkey
    Shooter
    Multi Format
    Posts
    15,943
    Images
    148
    Quote Originally Posted by Michael R 1974 View Post
    I for one do not hate organic chemistry, and appreciate the explanation. I think this is quite important as I doubt many are fully aware of the differences between Phenidone and its Dimezone derivatives. We sort of know Dimezone is "better" than Phenidone, but specifics are helpful. I think there was some good discussion about this in Mark Overton's XTOL clone thread.
    There's stable Phenidone derivatives, something that all Kodak chemists were well aware of, particularly as one senior research scientist helped edit LFA Mason's book "Photographic Processing Chemistry, and that included the section on Phenidone & the derivatives.

    Sure some developing agents in the Phenidone class are slightly better than others, the Dimezonnes are placed in this class as are other Phenidone derivatives. There's a deliberate attempt in these threads to deride Phenidone when it's been in use commercially for about 60 years with none of the issues.

    In terms of shelf life between the Phenidone derivatives and thei Dimezones, is not huge difference like a few weeks or months instead of 2 or 3 years and that's being overlooked.

    Interesting that PQ developers have a far better shelf life than MQ developers and in fact was why many manufacturers switched to them, that put's things into a better perspective.

    There's a lot of references to old data and books which refer to the original Phenidone which was unstable in highly alkali solutions and so never went int commercial production. Mason of Ilford refers to this instability so it's not something Ilford didn't address

    Ian
    Last edited by Ian Grant; 01-08-2013 at 05:43 PM. Click to view previous post history. Reason: add

Page 4 of 7 FirstFirst 1234567 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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