The Photographers Formulary Formulary Replenisher DK-50R, is used to extend the capacity of DK-50.
As a developer is used, its action is weakened by both the chemical reduction of the exposed silver halides in the emulsion and by the release of bromide ions into the solution.
The net results of reduced developer activity are reduction in the effective film speed and lower contrast. Adding replenisher ensures normal developer activity and partially counteracts the effects of the increased bromide concentration.
The shelf life of the replenisher solution is six months.