Argon gas makes for a better approach to leftover paint storage. It keeps oil-based paints, varnishes, and stains in freshly-opened-can shape and looking like new. A spray of argon gas creates a barrier between the liquid and the air inside an open can. This prevents the finish from curing, yellowing, or skinning-over. Argon is non-toxic, non-flammable, and inert, so it won’t react to other chemicals.