The embodiments herein relate to methods and apparatus for determining whether a particular test bath is able to successfully fill a feature on a substrate. In various cases, the substrate is a semiconductor substrate and the feature is a through-silicon-via. Generally, two experiments are used: a first experiment simulates the conditions present in a field region of the substrate during the fill process, and the second experiment simulates the conditions present in a feature on the substrate during the fill process. The output from these experiments may be used with various techniques to predict whether the particular bath will result in an adequately filled feature.