Mixing our own darkroom chemistry has become the established method around here. Since the demise of Zone VI chemistry, we are pretty much on our own when it comes to processing chemistry. Things like PyroCat-HD can easily be mixed by weighing out the necessary materials each time, since you are mixing stock solutions and it is not something you have to do every time you process film. I mix up the print developer as two stock solutions that are combined when a printing session starts. I keep one and two liter bottles of part A and B mixed and ready to go. That is just another element of the process. On the days we are not doing darkroom work, I am in there cleaning and mixing solutions.
One thing you use a lot of when making large prints is Fixer. We go through a lot of fixer, and I do not believe in skimping. The F-24 formula will fix 25 8×10 prints (or equivalent area, 80 sq inches per print) per liter. . . that would be 100 per four liter batch. I never run fixer more than 60% of capacity, so that would be 60 8×10’s per four liter batch. Another darkroom rule is, we never pour anything back into the container. . . most of the time. Used fixer is dumped into buckets in the garage and when I get a batch, it goes through the silver recovery unit.
Because we purchase Sodium Thiosulfate in 50 pound bags, this can present a storage problem, let alone a hassle for measuring and mixing. It was obvious that we needed to find some convenient way of storing and measuring large volumes of dry material. The solution is actually not that difficult. We already had an impulse heat sealer, all that was needed was bag material. You can purchase continuous rolls of poly tubing, and 4mil is a good choice. Making a custom bag is easy. Heat seal the end, cut off the length you need, measure the chemical, pour into the bag, squeeze out the excess air, and heat seal the other end. The only other thing you need is a label, or you can write on the bag with a marker.
For the F-24 Fixer we use, I measure out the correct amount of all three ingredients and seal them into an appropriate size bag. I use four inch wide 4mil tubing that comes on a 1,500 foot roll. I print off an adhesive label for each bag and store the small bags in plastic shoe containers and the larger bags in five gallon plastic buckets. When I need to mix fixer, just grab three bags, run water into a suitable container at the appropriate temperature, cut open the bags and stir.
You can purchase Poly Tubing from suppliers like ULINE in widths from 1 to 48 inches on large rolls. They also sell Impulse Heat Sealers in various sizes. The unit we have is the 12 inch model and has seen a lot of use over the years. Be sure to order a spare heating element service kit. Pick up some adhesive labels for your computer printer and you have everything you need to make your own prepackaged darkroom chemistry.
JB
