Newbie question about chemistry

Discussion in 'Darkroom Developing and Printing' started by the letter K, Nov 30, 2003.

  1. the letter K

    the letter K Guest

    I am familiar with the basics of processing a roll of B&W film, i.e.
    developing the negatives and making prints. HOWEVER, I have never
    mixed chemistry. In the near future I plan to begin doing so.

    I've done a lot of searching on the internet and reading various books
    in the library, but so far I've only come across rather non-specific
    descriptions of the process. Typically, such articles will say "mix
    the chemistry according to the manufacturer's instructions." However,
    I've examined a packet of D-76 powdered developer and didn't see
    anything that resembled specific instructions.

    My highly tentative understanding of mixing, say, D-76 developer is as

    * If I have a "makes one gallon" packet of D-76 powdered chemical, I
    am to mix that into 1 gallon of water and store the result in a
    suitable container. I can then use that mixed solution full-strength,
    or diluted at a 1:1 ratio (with consequences that I do not understand,
    apart from a necessary change in the amount of time the film stays in
    the developer).

    I'm assuming a similar concept applies to powdered fixer.

    If someone can suggest a website that contains Everything You Want To
    Know And Then Some, I would greatly appreciate it.
    the letter K, Nov 30, 2003
    1. Advertisements

  2. If you are talking about packaged chemisty there are
    usually complete instructions on the package. For powder one
    starts with something less than the final amount at a
    specified temperature. For most powdered chemistry the
    starging amount is around one half to three quarters of the
    final amount. For most developers the temperature is 125F,
    for Kodak fixer its 90F. After everything goes into solution
    cold water is added to bring the volume up to that required.

    If you are interested in mixing your own it becomes harder
    to find anything current with general instructions. My
    suggestion is _The Darkroom Cookbook_, Steven Anchell,
    Butterworth-Heinemann ISBN 0-240-80196-2 This is in print
    and easily available.
    Mixing from scratch is not at all difficult and is fun.
    You can mix solutions which are not available packaged and
    sometimes save a littl money. The last is sometimes not true
    because packaged chemistry, especially in small amounts is
    pretty cheap.
    Richard Knoppow, Nov 30, 2003
    1. Advertisements

  3. You have a lot of questions packed in there.

    1. Mixing Packaged D-76. First, as you are starting out, got for
    the one quart (one liter) size, not the one gallon. Obtain a one
    quart/one liter graduated cylinder. I measure metrically, so I will
    continue with metric measures here. Fill the graduated cylinder to
    about 700 ml with water at 125° F. (buy a digital thermometer from a
    kitchen store). Slowly add the D-76 mix while stirring gently with a
    plastic stirrer (available from any photo supply store or kitchen
    store). This will increase the overall volume to about 800 ml. There
    will still be some chemicals left in the package. So pour some hot
    water into the 'empty' package and pour it into the graduated cylinder.
    You will now be about 900 ml. Add water to make 1,000 ml (i.e. one
    liter). Pour the entire mixture into a storage container. For
    developers, I prefer a glass (brown or green if possible) container with
    a plastic top. Allow to sit overnight before use. This assures that
    the mixture has properly gone into solution. Store your developers in a
    refrigerator at 40° F. to retard the rate of oxidation.

    2. Mixing fixer. If the fixer contains sodium thiosulfate
    pentahydrate (as opposed to anhydrous), the water needs to be at 125° F.
    .. The reaction is endothermic and the solution post mixing will be
    about 70° F. Start with about 600 ml of water, as the pentahydrate
    contains water itself.

    3. You can mix D-76 from scratch materials more cheaply than you can
    buy it. And this allows you to mix other developers and more than one
    fixer as well. For this you will need a good balance. Digital ones are
    available for about $100, but you can buy a used triple beam balance on
    eBay for under $40. A supply of different size graduated cylinders is
    useful. I have 40 ml, 250 ml, 500 ml, 1,000 ml as standard measures.

    4. Using D-76. I started out using D-76 full strength and found
    that by roll 6 I was worried about development time and exhaustion of
    the developer. I have switched to using it 1:1 and throwing away the
    once used solution. The micro-image is finer this way and I know that I
    always have fresh developer to use.

    5. Literature. I second Richard's suggestion that you get
    Anchell, The Darkroom Cookbook, and also suggest Anchell and Troop, The
    Film Developing Cookbook. No working darkroom should be without them.

    6. Chemistry Safety and Technique. Safety. There are numerous
    safety issues, such as never add water to a strong acid. Always add the
    acid - slowly - to the water. Work in a well-ventilated area. Wear a
    respirator (Sears has adequate ones) and gloves if the chemicals are
    noted to be hazardous. I always do this for pyrogallol, glycin, and
    color developers CD-3 and CD-4, as well as some other chemicals as
    indicated on the label. Sometimes, e.g., when mixing packaged color
    chemistry, the powders can be hazardous, so it may be advisable to
    carefully slice open the package and lower it beneath the surface of the
    water (gloves on) before emptying it out. This prevents the release of
    hazardous powders into the air and assures that all of the chemistry is
    in solution. When dealing with hazardous raw chemicals, pour water
    into the container used to weigh them before dumping it into the
    solution. This reduces the problem of powder in the air.

    Technique. When making solutions from raw chemistry, the order in
    which chemicals are added is sometimes important. Some developers need
    an alkaline environment in which to dissolve, so adding sodium sulfite
    (or in at least one case, potassium carbonate) before the developer is
    added is necessary. Consistency of procedure is necessary to obtain
    repeatable results. Remember how you do a procedure and do it the same
    way every time (unless you learn that it is wrong for some reason).


    Francis A. Miniter
    Francis A. Miniter, Nov 30, 2003
  4. It may specify the temperature of the water to be used (warm water works
    best, as I recall, but the temperature is very non-critical).

    The instructions are probably something like "dissolve the powder in 3
    quarts of water with continuous stirring and then add water to make a total
    of 1 gallon."

    And then you store it -- preferably divided up into four 1-quart bottles, so
    you don't expose the whole thing to air whenever you use any of it.

    Glass bottles are much better than plastic at excluding air.
    And saving money.

    There really isn't much more to know.

    Clear skies,

    Michael Covington --
    Author, Astrophotography for the Amateur
    and (new) How to Use a Computerized Telescope
    Michael A. Covington, Nov 30, 2003
  5. the letter K

    geo Guest

    Mixing from scratch? You are required to go to:

    Get Darkroom Cookbook as others recommended. You can get a cheap digital
    scale for around $30. on ebay. Get one with at least a 200g capacity. You
    can get by without a scale using the teaspoon conversion method in Darkroom
    Cookbook but the scale is so cheap why not get one.

    Use D76 1:1 one-shot. Easier & better grain & resolution. I prefer D23. Just
    2 ingredients, works great.
    geo, Dec 1, 2003
  6. Just as an aside, I can tell you from experience that 1L soda bottles
    work well enough for this application. While it's true that glass is
    absolutely impermeable to oxygen, the plastic bottles are plenty good
    enough. They won't shatter and make a dangerous mess if (when) you
    drop one, and they can be had for practically free. Go and price some
    glass bottles and decide for yourself. Remove the label and indicate
    the contents with a Sharpie. I've been using them for a good while
    now and have not had any developer go bad from oxidation before it's
    Frank J. Schifano, Dec 2, 2003
  7. the letter K

    Dan Quinn Guest

    Dan Quinn, Dec 2, 2003
  8. the letter K

    Dan Quinn Guest

    For some time I used 12oz square water bottles. Smaller bottles,
    filled and sealed, used one at a time, may be a better solution
    for you. Four 250ml water bottles will hold 1 liter of stock. Dan
    Dan Quinn, Dec 4, 2003
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.