At the end of each painting session, pour your leftover solvents and spirits into a jar. The paint sediment will sink to the bottom leaving the liquid on top.
When you have collected enough, carefully tilt the jar without disturbing the sediment and pour the solvent through a coffee filter or papertowel into another jar.
A great way to be more environmentally friendly and to make your painting products last longer.
Photo: Il Vagabiondo / Unsplash