Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,922   Posts: 1,556,624   Online: 1284
      
Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 22
  1. #11
    Jorge Oliveira's Avatar
    Join Date
    Jun 2003
    Location
    Brazil
    Shooter
    35mm
    Posts
    614
    Bill Troops, author of the TF formulas (and co-author of the Film Cookbook) states that with alkali fixers you do not need HCA.

    HCA - Just some sulphite in water will do. No need to mix it in advance (half a 35mm film cannister is OK, solve, use and discard after).

    You may substitute borax for metaborate in the fixer (same amount; I used it both ways - no diference).

    Get good jars with good covers to store all that.

    Phenidone is very tricky to measure and solve, and many bad results with it are due to that. Make a 1 (or 2) percent solution and use it from the solution.

    Two suggestions:

    - Solve it in isopropyl alcohol (just alcohol - no additives like colors, perfume, etc). Some people use cheap vodka...
    - Solve it in a metabissulfite solution mixed at 5g/liter.

    I've used both; both works and I do not know which is the best.

    No Photo Flo?

    I do not use stop bath anymore - just plain water. No streaks or alike. All alkali processing.

    Jorge O

    Whew!

  2. #12
    Jeremy's Avatar
    Join Date
    Oct 2002
    Location
    Denton, TX
    Shooter
    Multi Format
    Posts
    2,767
    Images
    56
    I still have one of those larger sized bottles of photo-flo... can you mix that yourself?
    Let's see what I've got in the magic trash can for Mateo!

    blog
    website

  3. #13
    Jorge Oliveira's Avatar
    Join Date
    Jun 2003
    Location
    Brazil
    Shooter
    35mm
    Posts
    614
    AFAIK no...

    If one want to make sure your negs will last 100 yrs and so on, one shall not run risks.

    If one is daring (or don't care for archival storage), then dishwasher detergent, etc will work as well as...

    Somepeople uses only distilled water as last wash.

    Jorge O

  4. #14
    Ole
    Ole is offline
    Ole's Avatar
    Join Date
    Sep 2002
    Location
    Bergen, Norway
    Shooter
    Large Format
    Posts
    9,281
    Blog Entries
    1
    Images
    31
    First, the HCA /thiosulfate/rapid fix question:

    All fixers contain thiosulfate, except some very special ones which are truly nasty. So the thiosulfate is what does the job.
    There are two forms of thiosulfate used in fixers: Sodium thiosulfate and Ammonium thiosulfate. The sodium (Na) version is called "hypo", the ammonium fixers are usually called something with "rapid" in it. The reason for this is that the ammonium actually sppeds up the rate of dissolution of the silver halides. Since this is a function of the ammonium it's not specific to "ammonium thiosulfate". You get the same effect by ading a few teaspoons of ammonium chloride to a liter of Hypo fix - clearing times down to less than 20 seconds.

    Fixers are either acidic or alkaline (and some are almost neutral). Alkaline fixers wash out more rapidly. When using acid fixers, HCA will neurtalise the acid and make the film (or paper) alkaline - thus washing out faster. The HCA also helps converting some of the byproducts of fixing to more easily soluble compounds. Due to the more rapid washing after alkaline fix, this is not necessary unless using acid fix - or very old fix. If your fix is yellow, it's dead. If it gets really bad, it will work as a hypo toner - although not as cleanly.

    Don't worry about the life expectancy and capacity of the fix: If in doubt, make new. Compared to film, fixer is dirt cheap: Don't risk it.

    Phenidone is not very stable in solution: Measure new every time, a per cent solution is very unreliable.


    Sodium bisulfite and sodium metabisulfite have different formulas, but are thought by many to be the same chemical. They are certainly interchangeable.


    Pyrocat-HD: Instead of making a solution "B", I dissolve the equivalent amount of carbonate in the mixing water. For 1 liter of 1:1:100, use 6.5g of sodium carbonate monohydrate, or 7.3g of potassium carbonate. Dissolve in 1/2 liter water, add part A dissolved in the other 1/2 liter.


    Amounts: I suggest you reduce your KBr to 50 g, and buy 200g Hydroquinone. It's not used in Pyrocat-HD, but it is a very useful developing agent to have around. Some (250g?) Metol is useful to have, as well.
    -- Ole Tjugen, Luddite Elitist
    Norway

  5. #15
    Jorge Oliveira's Avatar
    Join Date
    Jun 2003
    Location
    Brazil
    Shooter
    35mm
    Posts
    614
    Ole

    I beg to disagree on this one.

    Mesuring minute amounts of phenidone requires a really good scale.
    If you do not trust the life of the solution, mix, use and discard.
    I have used my phenidone reserve solutions both in absolute ethanol and isopropyl alchool for a couple of months without any problem, and many years ago I've used it solved in metabissulfite.
    (all my developers, film and paper, are phenidone based - I was unable to find metol locally)

    Jorge O

  6. #16

    Join Date
    Mar 2003
    Location
    Greenville, SC
    Shooter
    Large Format
    Posts
    4,813
    Images
    5
    Much of the research suggests that phenidone is not very stable in solution. However, exactly what does that mean? In water? In alcohol? In acetone? In diet cola?

    I have found that phenidone is very stable in the Part A Stock Soluition of Pyrocat-HD. And I am using Phenidone A, not one of the more exotic variants of Phenidone. My Stock A solutions are good for up to six months, or slightly more. There is absolutely nothing in my experience to suggest that one will get better results by mixing the Phenidone from scratch for every working solution.

    The key to the stability of Stock Solution A, at least from my perspective, is the balance of preservative, i.e. sodiuim bisulfite, in Stock Solution A. There must be enough to preserve the reducing elements, but not so much that all staining is eliminated. I think we have just about the right amount in the Pyrocat-HD formula, though for sure with certain films and long development times one may need to add a pinch or two of sodium sulfite to reduce the possibility of general fog from developer oxidation.

    Sandy King

  7. #17
    Ole
    Ole is offline
    Ole's Avatar
    Join Date
    Sep 2002
    Location
    Bergen, Norway
    Shooter
    Large Format
    Posts
    9,281
    Blog Entries
    1
    Images
    31
    Sandy, I have found Stock Solution A to be very stable as well. My last batch was used over a three-month period, and I'm sure this one will last nearly as long.

    The concerns over the stability of Phenidone apply if you wish to mix that in a solution on its own, say 2g in some volume to add 1/10 of that in making up Pyrocat A. This pre-stock solution could easily sit around for a year, at which time the stability would be important. With the relatively low solubility of Phenidone, it takes quite a lot of water to dissolve 2 grams...

    I don't advocate measuring 0.002g Phenidone for every working solution of Pyrocat-HD, but I think it is a good idea to use a balance precise enough to measure 0.2g for every STOCK solution.
    -- Ole Tjugen, Luddite Elitist
    Norway

  8. #18

    Join Date
    Mar 2003
    Location
    Greenville, SC
    Shooter
    Large Format
    Posts
    4,813
    Images
    5
    Ole,

    My understanding is that it is the acidity of sodium bisulfite that provides the preservative. I don't have any experience with the stability of phenidone in other solutions, especially alkaline ones.

    Regarding precise measurments, check out the site below for a digital scale capable of measuring to 0.001g.
    http://www.balances.com/myweigh/i200-scale.html

    Sandy

  9. #19

    Join Date
    Mar 2003
    Location
    Greenville, SC
    Shooter
    Large Format
    Posts
    4,813
    Images
    5
    Sorry, the precision of the iBal 201 is 0.01g, not 0.001g.

    Can't imagine what kind of precision would be involved with 1/1000 of a gram. Even at 1/100 of a gram the display weight fluctuates when you breath close to the scale.

    Sandy

  10. #20

    Join Date
    Nov 2002
    Posts
    129
    Most of those kind of scales (which costs thousands of dollars) usually have a sliding cover to block all outside influences. Some can read to .1 or .01 mg precision. Fun to use, but overkill for photography!
    Nobody ever went broke underestimating the intelligence of the American public.

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