Abstract: Disclosed is a method for determining the strength of a metal processing solution, defined herein to include electroless metal plating solutions and chemical etching solutions wherein a metal is plated onto and stripped from, respectively, the surface of a metal substrate. A pair of electrodes, preferably composed of the metal being plated in the case of an electroless metal plating solution or the metal having been etched in the case of a chemical etching solution, are immersed spaced from one another in the metal processing solution. A voltage is gradually applied across the electrodes and steadily increased. As the voltage is increased, the current flowing between the electrodes in the solution is monitored. The point at which the current first passes through a maximum value and begins to decrease is recorded as a function of time or voltage and is correlated empirically with the strength of the metal processing solution.

Abstract: A pair of relatively inert metal electrodes 14 and 16 are immersed in a metal processing solution 10. The metal processing solution 10 is of the type that oxidizes a metal dissimilar from that of the electrodes from the elemental state to the ionic state. A predetermined potential is applied for a predetermined time across the electrodes to create a direct current through the solution, thereby plating a determinable quantity of the metal ionic species on one of the electrodes as a metal. After the potential is removed from the electrodes, the elapsed time required for essentially all of the metal to be reoxidized to the ionic state by the processing solution is measured. Since the plated metal is dissimilar from that of the electrode, a galvanic cell is formed. Thus, the elapsed time can be measured, for example, by coupling an external load in series with the two electrodes and noting the elapsed time during which a current flows through the load.