Hi CabnetMan, thanks for the info. Not sure what you mean by film finish? The bench is peeling away because it was left in the rain for a short while and the varnish was damaged on the ends. Im sur an Oil finish woul look the best and be good for UV rays but would it stand up to young kids and not show scrathhes? Also it would be nice to wash it down with water sometimes. Would oil finish hold up to that? Thanks!
A film finish is one that dries/cures with a non-porous layer (film) on top of the wood. The first application or two may penetrate the fibers of the wood and additional applications build on top of those. Some film finishes like acetone based lacquer melt into the previous coats. Others like oil base polyurethane just get stuck to the previous coat.
An oil finish, like BLO (boiled linseed oil), pure Tung oil, and a product like Penofin, penetrate the wood fibers. When continuous applications are applied, the wood gets saturated, and a surface forms by drying/curing. It does not dry like a layer of its composition, like lacquer or varnish. It does not get crispy or chalky.
Wood always has some amount of air and moisture. Untreated, it will continually exchange air and moisture depending on its environment. If you encapsulate that wood with a coating that does not permit those natural occurrences, the film will expand and contract, gaseous vapor can develop between the wood and the finish. So, what will happen is the finish will get brittle, chalky, and likely peel away. Refurbishing this finish requires it to be sanded or stripped to the point that it can be re-applied.
Oil finishes, OTOH, don't react to the environment like film finishes. To refurbish an oil finish, may only require a good cleaning and re-application of the oil. You are asking for a finish that offers a hard durable scratch free surface, and one that will survive the environment. One finish will not do both, and still offer easy maintenance. Your closest bet would be a spar varnish, or a spar urethane. But, be prepared for the rigor of maintenance, as any of them will require the labor of a film finish. When they start to fail, it sure is an ugly sight.
You have to decide whether you want to preserve the wood and its look, or have a protective finish.