XTOL replenishment rate and rolls per liter

The table is Kodak's, for rolls of 135-36 or 120 (80 square inches of film each; a 220 roll counts as two). The last row says "adjusted" time, so the second step is 15 percent on top of the first: 1.15 x 1.15 = 1.3225, or +32.25% on the normal time. Kodak says to discard the developer after 15 rolls per liter.

The sheet states its bands per liter. For a bigger or smaller bottle, the form above divides your roll count by the liters, which is my scaling; Kodak does not print it. A 5 liter batch is rated for 75 rolls, and the first 25 use the normal time. Roll 26 gets +15% and roll 51 gets +32.25%.

This is the same kind of rule as the one in the developer reuse calculator, except that the steps compound. The starting time itself comes from the film's table in the sheet, at 20 °C. If your developer is warmer or cooler, the temperature calculator moves it.

Kodak says you can replenish XTOL in systems that use the full-strength solution, not the diluted one. The rate is 70 mL of XTOL for each 135-36 or 120 roll, or each 80 square inches of film. After 10 rolls that is 700 mL.

Kodak suggests watching a replenished process with its black-and-white control strips and moving the rate up or down in 10 mL steps, allowing time for the process to settle between changes, and using the lowest rate that keeps the process on aim. The sheet also says some rotary-tube processors allow replenishment. A tank with a floating lid keeps replenished stock indefinitely, as long as new solution is added to replace what the processor used. Seasoned developer from a replenished process can also be used in an unreplenished batch, and the sheet lists starter amounts for pre-seasoning fresh developer.

Diluted 1:1 (developer to water), XTOL is for one-shot use. Kodak says to dilute it just before use, discard it after one batch of film and never replenish or reuse it. The diluted solution needs enough active ingredient, so Kodak recommends starting with at least 100 mL of full-strength developer for each roll. Its example: 4 rolls at 1:1 need at least 400 mL of stock, which makes 800 mL of working solution, even if the tank would take less.

Kodak says 1:1 gives slightly greater film speed, enhanced sharpness and shadow detail, and slightly more grain. For other ratios and tank sizes, the dilution calculator does the arithmetic.