The combination of cobalt and iron toner generates violet to blue-violet
hues. The degree of toning depends on the dilution of and the duration
in the cobalt toner. Shorter toning times only generate a subtle
tone in the highlights. Longer toning times also affect the shadows.
The subsequent iron-blue toner only reaches those areas that have
not yet been fully toned by the cobalt toner.
Prepare the working solution of cobalt toner just before you
use it. It is only usable for about 60 minutes!
All the solutions
in the kit combined make up between 2.5 and 5 litres of working solution.
The stock solutions have an almost unlimited shelf life. So it makes
sense to only prepare the amount you absolutely need.
solution of the iron-blue toner has a shelf life of several months
and can be used until exhausted.