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  1. #21
    Photo Engineer's Avatar
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    Ian is correct. Getting a formula in terms of Baume is virtually untranslatable depending on chemical. And, the formula was carbonate free, so we only have an Ersatz Rodinal formula.

    Baume measurements is also a problem with old emulsion formulas.

    PE

  2. #22
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    Actually I've found that for some chemicals transposing the Baumé to percentage W/V is remarkably easy.

    In the case of "100 cc of liquid sodium bisulphite of density 35 degrees Be" that's actually just a 29/30% solution w/v and in fact is the strength of commercially available Sodium Metabisulphite solution, sold in bulk

    So armed with the Specific Gravity's of the chemicals used in Ridinal it'll be easier to get close to the formula for Rodinal/R09

    Ian

  3. #23

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    History of Rodinal formulas a branch of literature not science.
    Here's one from 1902:
    http://rodsmith.org.uk/photographic-...20-%200663.htm

  4. #24
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    Quote Originally Posted by Ian Grant View Post
    Actually I've found that for some chemicals transposing the Baumé to percentage W/V is remarkably easy.

    In the case of "100 cc of liquid sodium bisulphite of density 35 degrees Be" that's actually just a 29/30% solution w/v and in fact is the strength of commercially available Sodium Metabisulphite solution, sold in bulk

    So armed with the Specific Gravity's of the chemicals used in Ridinal it'll be easier to get close to the formula for Rodinal/R09

    Ian

    As you said previously, it can be difficult. Ammonium Hydroxide is one of those that is difficult due to having densities lower than 1.0.

    PE

  5. #25

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    dont know if this is any use, i have acopy of photography and focus dated 1915 with an ad for rodinal now british made. also a1912 agfa handbook with a few recipes in. dave.

  6. #26

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    Quote Originally Posted by Photo Engineer View Post
    As you said previously, it can be difficult. Ammonium Hydroxide is one of those that is difficult due to having densities lower than 1.0.

    PE
    According to Wikipedia:

    At 20 °C, the relationship between specific gravity (s.g.) (relative density) and degrees Baumé is

    For liquids denser than water: s.g. = 145 ÷ (145 - degrees Baumé);
    For liquids less dense than water: s.g. = 140 ÷ (degrees Baumé + 130).
    An older version of the scale for liquids heavier than water, at a reference temperature of 15.5 °C, uses 144.32 rather than 145.

    Hydrometers for measuring densities less than 1.0 are easy to find. API gravity hydrometers (American Petroleum Institute) are typically less than 1.0, and sometimes have SG scales as well.
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

  7. #27

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    And my 18th Ed. CRC from 1932 lists degrees Baume for Aqua Ammonia and displays it for % Ammonia as well as Sp. Gr.
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

  8. #28
    Ian Grant's Avatar
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    And to make life even easier many Photo chemicals are sold as solutions, and the data-sheets show the Specific Gravity's.

    Ian

  9. #29

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    An aside: in early manuals, Agfa referred to p-aminophenol as Rodinal, a proprietary name for the developing agent. That was distinct from Rodinal developer.

  10. #30
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    Quote Originally Posted by Kirk Keyes View Post
    According to Wikipedia:

    At 20 °C, the relationship between specific gravity (s.g.) (relative density) and degrees Baumé is

    For liquids denser than water: s.g. = 145 ÷ (145 - degrees Baumé);
    For liquids less dense than water: s.g. = 140 ÷ (degrees Baumé + 130).
    An older version of the scale for liquids heavier than water, at a reference temperature of 15.5 °C, uses 144.32 rather than 145.

    Hydrometers for measuring densities less than 1.0 are easy to find. API gravity hydrometers (American Petroleum Institute) are typically less than 1.0, and sometimes have SG scales as well.
    Kirk;

    When I did a search for Baume several years ago, I found no wikipedia entry or indeed no wikipedia. The results I did turn up were those that gave both methods of conversion including 2 for heavier than water and 2 for lighter than water.

    Unfortunately, one cannot say which method was used in the above, and the conversion is not very straightforward according to some of the literature I had.

    Fortunately, I have a rather complete set of hydrometers that are handy when needed!

    After several hours thinking this over, I realized that every encounter with solutions specified in Baume units ended up being an unsatisfactory formula. In some cases, the conversion (as best I could do it) was either wrong or virtually impossible. I have become kind of negative or uncomfortable overall when I use Baume.

    PE
    Last edited by Photo Engineer; 08-19-2009 at 09:44 PM. Click to view previous post history. Reason: Add last paragraph

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