Improved film cooling hole geometries and effect of coolant density on film cooling have been a focus since the 1970s. One of the first studies on modifying hole exit to improve film cooling effectiveness and quantifying coolant density effect was from Prof. Goldstein’s group . This paper traces the development and implementation of hole exit geometries as well as coolant density study from this landmark paper and its impact on future studies of advanced hole geometries under realistic engine-like coolant to mainstream density ratio conditions. This work is not intended to be a comprehensive review of the literature. It is aimed at providing an overview of the influence of ref.  over the past 4 decades.