Tmax RS Replenishment vs Exhaustion Rates

Discussion in 'B&W: Film, Paper, Chemistry' started by AlbertZeroK, Jan 21, 2012.

  1. AlbertZeroK

    AlbertZeroK Member

    Jan 16, 2011
    Central Virg
    Medium Format
    I've been playing around with TMax RS which I think is much cheaper to use than TMax Developer which I'm a fan of. But the instructions say, add 1.5 oz per roll of fill, yet the exhaustion rate is 2 oz per roll. Right now, I'm using 1/2 gallon of working solution with 1/2 gallon of replenishment solution, so when my replenishment stock is up, I'll likely mix box a new working and replenishment stock. But is it me, or if I continued replenishing the working stock the way they say, it will eventually stop working? Am I the only one that sees an issue with the math, or am I missing something?
  2. Ian C

    Ian C Member

    Feb 8, 2009
    Large Format
    Top of Kodak PDF J86 page 2 “Mixed solution used as a working-tank solution or a replenisher.”

    I didn’t see any reference to “…the exhaustion rate is 2 oz per roll” in Kodak’s J86 document. Of course, I might have missed it.

    Here I think that Kodak’s use of the word “solution” refers to the working strength solution of concentrate plus water used as a replenisher.

    In 1.5 ounces of replenisher mixed at the standard 1 + 4 you’d have 0.3 ounces (or 8.9ml) of concentrate. That plus the active chemical already present in the larger volume of once used developer should give you approximately the correct chemical activity for normal development per Kodak’s testing.

    On page 1 of J86:

    “T-MAX RS Developer and Replenisher is available in convenient sizes to make one gallon and ten gallons of solution; use this solution as a working-tank solution or a replenisher.”

    I think the idea is to mix, say 1 gallon at 1 + 4, use whatever volume less than 1 gallon you find practical and add 1.5 ounces for each roll (or 80 square inches) of film processed to recharge the developer in the tank.

    You might mix your 1/5-gallon of concentrate + 4/5-gallon of water to make 1 gallon at the specified concentration of 1 + 4.

    Use the first half-gallon in a large tank to process, say, 6 rolls per processing run. You’d have 64 ounces left in the mixed supply bottle. By adding 9 ounces per run (6*1.5oz/roll = 9oz/replenishment) you could replenish 7 times.

    Your capacity is 6 rolls initially + 7*6 rolls = 6 rolls + 42 rolls = 48 rolls per gallon of working strength developer at 1 + 4.

    That’s Kodak’s stated capacity for T-Max developer. I’m not sure if this is the same for T-Max RS developer.

    I think that the best policy is: once you’ve got Kodak’s stated 48 rolls per gallon of working strength developer, it’s best to scrap it and start over with a new gallon.
    Last edited by a moderator: Jan 21, 2012