Film-Forming: This type of finish creates a physical barrier on the surface, protecting the wood from the elements and damage. Film forming finishes typically retain colour longer than penetrating stains but needs to be properly maintained to prevent flaking and cracking.  Penetrating Finish: A durable finish where the stain soaks into the wood’s cellular structure to prevent water penetration. The finish will not last as long as a film forming but doesn’t have the same strict maintenance timeline as the finish simply fades instead of peeling.