I'm confused. Doubling the concentrate's formula will give you 30-40 ml of concentrate. That would be mixed into enough water to produce 2 litres of working developer (and don't forget to add the sodium sulfite). So the dilution is around 1+63 to 1+49, depending on the concentrate.
Originally Posted by Bruce Osgood
Regarding weighing: The Phenidone (or Dimezone S) is the tough part, as you pointed out. For doubling, you need .1 g of Phenidone, and if your balance has a resolution of .1 g, then you might be off by half of that .1 g resolution, which is .05g. So a measurement of .1 g might actually give you .05 to .15 g of Phenidone, which is too inaccurate. That's why I recommend using an electronic scale with .01 g resolution. These cost only $12-15; search for "scale .01g" on amazon. Even then, I suggest measuring .1 g very carefully. Quadrupling the formula (60-80 ml of concentrate) means measuring .2 g of Phenidone, which is easy with a .01 electronic scale.