Agfa 304 Rapid Fixer

I was looking for a formula that would use up some of my ageing stock of sodium thiosufate and thought I’d try this one from the Darkroom Cookbook (Formula #124). The combination with ammonium chloride results in a faster fixing action. I also find it fairly odourless.

  • Water at 52°C‡ – 750ml
  • Sodium Thiosulfate – 200g
  • Ammonium Chloride – 50g
  • Potassium Metabisulfite† – 10g
  • Water to make 1 litre

‡Hypo (sodium thiosulfate) is endothermic, which means that it absorbs heat as it dissolves, hence the warm starting temperature.

†The metabisulfite is to acidify the fixer; I reduced the amount from that stated, using half, as I use this fixer with films processed in PMK where an acid fix can sometimes affect the desired negative staining.

2 Responses to Agfa 304 Rapid Fixer

  1. Joe says:

    Do you know if sodium bisulfite can be substituted for the potassium metabisulfite?

  2. Roy Hammans says:

    Hi Joe, Apologies for the late reply but you’ve probably discovered by now that substitution with sodium bisulfite is perfectly okay. Potassium metabisulfite is readily available though, from brewing and winemaking suppliers, whereas the sodium salt is harder to track down. Guessing you already have some though!

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