[albada]

Proprietary formula? The origin of Xtol is described in detail in "The Genesis of Xtol," by Dick Dickerson and Silvia Zawadski (Photo Techniques Magazine, Vol. 20, No. 5, 1999, p. 62 ff). The article also includes the formula.

@Rudeofus: My formula requires that 90 g/L of sodium sulfite be mixed in separately from the concentrate. That makes it a little more hassle than HC-110, but it also means it gains the buffering and other benefits from the sulfite.

@BetterSense: My motive for creating this concentrate is to have something that will last for a few years. After mixing, XTOL lasts 6 months according to Kodak, and I can't use 5 litres in that time. So this concentrate is intended for people who shoot 2 rolls per month or less as a hobby. Those who shoot 3 rolls per month or more will be able to use all 5 litres of XTOL (undiluted) in 6 months. But for low volume shooters, the extra few minutes it takes to measure two things (sulfite and concentrate) is not a problem.

@PE: Thanks for the encouragement, and the note about alcohol. From prior tests with similar formulas, I believe sharpness will equal XTOL. But I'll certainly run sharpness tests with the actual concentrate. For now, grain is the main thing I'm watching, while keeping development-times identical to XTOL.

@Gerald: Do you know if the formula from that article matches the patent? I have the patent, but haven't been able to locate that article. If you have access to that article, can you post the formula?

Mark Overton