
Worrying too much about wood movement and benchtop flatness.
Woodworking bench top finish. The third option which i use myself is nothing at all. And the thickness of the planks. A film finish lacquer shellac varnish poly varnish is not the way to finish a workbench top. Primarily i used it as a power tool bench but it was big enough that i also could use it for general assembly and finishing tasks the top was a full 4 8 ft.
Wood moves but obsessing about it while designing the bench wastes more energy than dealing with it after the bench is built. A good coat of wax is another option. The poly will let you clean up pretty well. Your bench will go out of flat.
Thick douglas fir bridge planks which are about 12 inches wide. Varnish will probably offer the longest most durable life. In my own case i built my current benchtop more than 35 years ago. This table top is also made from the hardest wood out of any manufacturer we reviewed.
The top measures 3 ft. While the standard thickness of the table top for a quality woodworking bench is 1 with lesser models often offering only of thickness the grizzly provides a 1 thick table top. The doubled up mdf was dead flat smooth and surprisingly durable and at the time i think i could buy two 4 8 sheets of it for under 40. For the finish on the top of my bench i used bee s wax dissolved in gum turpentine then mixed with boiled linseed oil.
If that is the case seal the wood with one coat of de waxed shellac or zinsser sealcoat. It took a couple of days to cure but it is a decent finish with the added benefit that glue paint etc. In fairness this can be both a blessing and a curse. Once a film finish is penetrated it looses its effectiveness and adjacent areas begin to fail.
My bench top is made of 3 in. A workbench is going to get dinged and film finishes will crack or craze or be otherwise damaged. Otherwise skip to the next step which is to apply several coats of oil based gloss polyurethane. You can finish the other surfaces of your bench however you like with whatever finish you prefer.
Build the finish until you like the look and enjoy your workbench. If you are really going to do actual work on that workbench top then it won t look pretty very long.