my usual hookup for C41 chemicals is out of stock for the forseeable future, and B&H does not stock any 2L chemical kits, so I'm wondering if anyone has successfully doubled a 1L kit. better safe than sorry with this expensive hobby :)

I need the 2L kit because I use a large tank that is approx. 2L.

  • \$\begingroup\$ What do you mean by "double"? Mix two kits together? Should be fine (concentration is the same). Mix a kit with double water? Concentration would be half, and you would need to adjust development times, if it works at all. \$\endgroup\$
    – xiota
    Jun 9, 2020 at 17:24
  • \$\begingroup\$ @xiota you know when a recipe yields 12 cookies but you want 24? \$\endgroup\$ Jun 9, 2020 at 17:32
  • \$\begingroup\$ @xiota I am trying to make a 2L kit from two 1L kits. very simple. not trying to dilute the mixture or anything crazy. \$\endgroup\$ Jun 9, 2020 at 17:33

1 Answer 1


Yes, you can safely combine two 1L kits (from the same manufacturer, please!) into a single 2L quantity. Just use twice the starting water, mix the ingredients in order as instructed, and top up to 2L instead of 1L when everything is in for each solution.

Be sure to mix both bottles or bags of each component (Part A, Part B, etc.) before going on to the next component -- mixing out of order may lead to solubility issues due to things like pH being wrong for something to dissolve.

  • \$\begingroup\$ thanks! just curious, have you done this before? \$\endgroup\$ Jun 9, 2020 at 21:30
  • 1
    \$\begingroup\$ @ChumiestBucket Not with prepackaged chemistry. I've made "mix your own" developers in various batch sizes since I first started mixing my own chemistry. Same deal, add all of each component in the correct order. Works fine. \$\endgroup\$
    – Zeiss Ikon
    Jun 10, 2020 at 11:03

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