The prints should be left in the toner until the desired tone is obtained, then washed thoroughly in plenty of water. With some papers, the effect can be similar to a sepia tone. Two of the solutions used are identical to ones used in the Iron toner above, so if you have already tried the iron toner, then you only need one extra chemical to make this one. 10ml Water to 500ml Mix the chemicals together in the order given, and pour into a developing tray. 500ml is sufficient to tone up to 5 10x8 prints.
More solution can be mixed if larger prints are to be toned.