How do I know if the paint I bought is water-based? October 19, 2023 17:40 Updated All ECOS paints, stains, varnishes and specialty products are water-based. Related articles How do l know if I need a primer? Does your paint contain any rust or mildew inhibitors? How long does ECOS paint last once opened? Do you sell paints for exterior use? What is the difference between the ECOS and Lullaby product lines?