The most common surface for oil paint, which has been used for centuries, is stretched primed canvas. Stretched canvas, also known as flexible supports, is susceptible to tears and sagging and becomes brittle. Modern alternatives include plywood panels, medium-density fiberboard (MDF), and hardboard. The disadvantage of rigid wood supports is that they warp and crack. Aluminum composite material or ACM panels offer one of the best choices for today’s artists. Lightweight and strong, they do not warp, crack, tear or sag.