I am not familiar with the sodium citrate used in kallitype. I know that those of us using potassium oxalate for palladium and platinum use it anywhere from room temperature to 160 degrees and higher. The higher the temperature, the warmer the print tone. I don't know if this is advisable with the sodium citrate. I would guess that anywhere from 70-90 degrees F would certainly be a reasonable place to start. Maybe Sandy will chime in with his experience with sodium citrate.....