Flashing at tablet edges, an inevitable phenomenon when tableting a plastically deforming material under a high pressure, can introduce significant errors to tablet density and porosity determinations due to overestimated tablet thickness when tablet were measured out-of-die. Errors in tablet density determination also lead to errors in true density obtained by the Sun method, which is suitable for water-containing solids. Errors in true density and tablet porosity propagate to fundamental parameters, derived from common equations, for quantifying mechanical properties of compacts. In this work, we have developed and validated a method to eliminate tablet flashing using sand paper. Using binary mixtures of water-containing plastic materials, we have further demonstrated the impressive improvement in powder deformability assessment by using accurate density of tablets free from flashing. (C) 2016 Elsevier B.V. All rights reserved.