The first thing to do is to choose a suitable container for cleaning your brushes. Bristle Magic will breakdown some plastics. For safety, if you are not sure of the container place a suitable material from the list of PET, Ceramic, and Glass underneath your cleaning container for safety. Acrylic paint and some plastics have similar properties and we know Bristle Magic softens hardened acrylic paint. A container made of PET plastic will have a "1" in the triangle with the letters PET below. Examples of reusable plastic bottles for cleaning your brushes with Bristle Magic are plastic milk bottles and plastic water bottles.