Procat with sodium carbonate

Discussion in 'B&W: Film, Paper, Chemistry' started by aligndont, Oct 28, 2005.

  1. aligndont

    aligndont Member

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    Would anybody know what the formula would be for solution B of pyrocat if sodium carbonate was used instead of potassium carbonate. Also, what would the technical differences between the two carbonates from an image perspective?
     
  2. moose10101

    moose10101 Member

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  3. lee

    lee Member

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    I just researched that and found what I needed to know on www.unblinkingeye.com under the articles. Sandy King wrote a great piece on Pyrocat HD Read that and somewhere it talks about substituting Sod Carb for Pot Carb. What I did today was went to the grocery store and bought Arm and Hammer Washing Soda and used 200grams in 1 liter of water. Then when you make the stock you need to use the 1+5+100 or 2+10+100 depending which dilution you use. I have not tested this yet but according to Sandy that Sod Carb will act exactly as Pot Carb has or does.

    lee\c
     
  4. sanking

    sanking Member

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    What Lee says is correct. There is no difference in image quality between sodium carbonate and potassium carbonate in the Pyrocat-HD formula. I tested both carbonates extensively and eventually established the standard formula with potassium carbionate because it is much more soluble in water than sodium carbonate, about j100% compared to 20-25%. I personally find the 1:1:100 or 2:2:100 dilutions simpler to work with than 1:5:100 or 2:10:100, but others may find advantages in the cheaper sodium carbonate, which is often also available locally, say in home and pool supply stores. But the bottom line is that they both give the same results, assuming you adjust for strength.

    Sandy
     
  5. aligndont

    aligndont Member

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    Thanks for your replies Sandy and Lee. I will try sodium carbonate with the metol version.
     
  6. Peter Schrager

    Peter Schrager Subscriber

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    Na Carb

    I've only used the Na Carbonate formula since that is what I had handy. Seems to work fine and produces some excellant negatives. Hats off to Sandy King!
    Peter
     
  7. sanking

    sanking Member

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    OK, but there are slight differences in results between the metol and phenidone versions, unlike sodium versus potassium carbonate.

    The metol version, with equivalent dilution and agitation, gives slightly more apparent sharpness, but slightly less EFS. You would probably not be aware of the difference unless you tested carefully with good control of your sensitometry and plotting, but the slight differences noted are there, at least in my testing.

    Sandy
     
  8. Claire Senft

    Claire Senft Member

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    For myself I put the amount of A solution into a liter of water and then directly add washiing soda to that mixture. For example if I am using 10 ml of solution A in a liter of water I simply add 7.5 grams of washing soda. It will go into solution very easily and I find weighing it no more trouble than measuring it.
     
  9. Ole

    Ole Moderator Staff Member Moderator

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    Claire;

    I do it the other way round: Dissolve the carbonate first, then pour in the A solution.

    I don't like the "trails" of oxidised developer after the sinking bits of carbonate - the other way round looks less scary. :wink:
     
  10. lee

    lee Member

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    Today, I developed film with pyrocat hd using Sodium Carbonate instead of Potassium Carbonate. I used the ratio of 2+10+100 as suggested by Sandy King. The color of the unused was a nice light brown color. The negs were stained great and looked great.

    lee\c