This paper is the result of two round robin activities run by the Technical Committee TC12, Pharma Packaging, of the International Commission on Glass (ICG). It deals with the phenomenon of delamination, that is, the formation of lamellae or flakes in drug products due to specific and localized corrosion of glass vials, and it follows a first paper PDA J Pharm Sci Technol. 2018, 72, 553-565where a testing protocol for the evaluation of the delamination propensity was proposed. The results showed that the protocol gives information on the quality of vials with respect to the propensity to corrosion, but no direct correlation with delamination could be demonstrated, as no lamellae formation was observed. In response, further testing was carried out on five sets of vials with expected low delamination propensity, compared to a set of vials with high expected delamination propensity using both the proposed protocol and a more aggressive protocol. The objective was to observe lamellae at least in the high propensity vials to show a correlation to initial test protocols.