Plywood if the top of your bench will finish flush with the frame a good low cost option is to use plywood for your workbench top.
Best finish for woodworking workbench. I have used watco danish oil natural color one some wood projects including my workbench base and i like it pretty well. Oil finishes don t provide a protective film that sits on top of the wood like varnish does. On the downside it will only give you about a year of protection from the ravages of outdoor life. Let it cure completely.
Option 1 finish your workbench with polyurethane. It puts a thin protective film down that will help keep glue paint and other gunk from sticking to the workbench top. I have a bunch of questions. Instead oil soaks into the wood fibers and dries.
Option 3 don t use anything to finish your workbenc. If you are really going to do actual work on that workbench top then it won t look pretty very long. Finish the top with a danish oil stain and wax for a good work surface that will last and is easily retouched with a new coat of. It is less slippery takes all sorts of abuse and best of all can be easily cleaned and resurfaced when needed.
Option 2 finish your workbench with a high quality wax. An exterior oil finish is definitely the simplest quickest way to treat an outdoor project. A workbench as its name implies is to work on and frankly the best surface to work on is raw wood. Use a biscuit joiner to fit the pieces together into a solid top.
I would recommend a drying oil finish something like a watco danish oil. Best finish for plywood workbench top. I ll be happy to tell you how to do a gloss finish on your bench but that still leaves me wondering why. Varnish will probably offer the longest most durable life.
In his article on flattening workbench tops chris schwarz mentions finishing them with a wipe on varnish and oil finish. It s easy to apply and looks good.