Microplastic paint particle production for spiking experiments; silicone rubber as application material provide high yield with low effort

Abstract

Paint particles are a highly-important but as-yet overlooked type of microplastic commonly found in coastal sediment, although research interest is growing. There is a need for paint particles as laboratory standards for spiking experiments, however, given paint is generally only available for purchase in liquid form, a new method is needed to reliable produce laboratory-grade paint particles. The main distinguishing issue with paint particle production (as opposed to other microplastic production) is the paint must be applied to a surface in layers before then being decoupled to be processed into particles. Since paints, and especially primers, are designed specifically to strongly adhere to surfaces, using the right application material is highly important. This study tests the time and material efficiency of 2 different application materials; laboratory wax film (i.e. Parafilm®) and silicone rubber sheets (i.e. silicone baking sheets). Silicone rubber was on average 36 × more time-efficient than laboratory wax and was also 8 × more material-efficient (8 × more paint particles were produce per liquid paint used). Indeed, silicone rubber provided an essentially-perfect decoupling process, as the paint could be easily peeled away in a solid and complete layer. As such, for the future production of paint particles for laboratory purposes, silicone rubber is highly recommended as an application material.