A fast and simple XTOL clone?

Photographica,Projects — Jordan on November 16, 2006

The developer known as MYTOL is described elsewhere on this site. It’s a homebrew formula that has been around for quite some time (it is in the first edition of the Film Developing Cookbook) and is meant to be used like XTOL. In my experience, it does indeed work just like XTOL — including the part where the stock solution goes sour unexpectedly!

My guess is that Paul Lewis, who came up with the formula for MYTOL, started with Kodak’s XTOL-related patents and MSDS and used the information in them to “back-formulate” something that resembles the original. Lewis didn’t include a metal-chelating agent like Calgon, EDTA or salicylate in his formula, though.

Deconstructing the ingredient list for MYTOL is telling. The developing agents are ascorbate and phenidone, just like in XTOL. However, MYTOL calls for an ascorbate salt directly (sodium ascorbate) rather than specifying the more easily obtained ascorbic acid. The formula also calls for sodium metaborate (an alkali) as well as both sodium sulfite and sodium metabisulfite. Both sulfite and metabisulfite are sources of “sulfite” ion in solution, but metabisulfite also produces a drop in pH in its solutions. I suspect it is in the MYTOL formula as an attempt to control the pH of the stock solution and bring it close to the target XTOL pH of 8.2.

It strikes me that a much easier way to mix MYTOL would be to start with a solution of ascorbic acid, phenidone, and sodium sulfite in water, then titrate to pH 8.2 with your base of choice (triethanolamine or metaborate would be good at this pH). The advantage here would be a shorter ingredient list with more easily obtained components.

Based on these considerations and my own experimentation, I propose the following formula for Instant MYTOL:

Instant MYTOL

Start with 700 ml of water
11.5 g ascorbic acid (same molar concentration of ascorbate as MYTOL)
0.15 g phenidone
60 g sodium sulfite (anhydrous)
13.4 ml triethanolamine or 7 g sodium metaborate (“Kodalk”)
Water to 1000 ml

Use as you would use XTOL. I suspect the triethanolamine version might be better behaved in dilute solution than the metaborate version, though metaborate is somewhat easier to handle.

Please e-mail me if you actually try this!

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