There countless ways to finish wood, and countless opinions to match. Finishes protect the wood from moisture and UV damage, and can enhance the appearance of the wood. It can be as quick and simple as a single coat of stain, or as complex as a multi-layered epoxy coating. A bench may last longer with a high-effort finish, but if it often needs re-finishing due to graffiti or grime then the effort will be wasted.
The two main options for finishing are staining or painting. Staining is easier and enhances the wood look, but painting is more durable.
For most of our benches, we have use a cheap water-based semi-transparent deck stain & sealer (specifically Olympic Maximum in “Redwood” or “Cedar”) which only seems to last a year or two. This is acceptable as we expect to paint-over the benches every few years to keep them looking good. For redwood benches, we have used an oil-based deck stain, which enhances the deep red color and can be more easily re-applied (rather than painted-over).
Before or After Assembly?
Finishing can be done before or after assembly.
If finishing with a stain, we recommend finishing before assembly as it is easier to handle the parts and reach all their sides.
However paint may be scratched or interfere with screw/bolt connections during assembly, so painting afterwards may be better.
Art and graphics usually can only be applied after assembly.
Stain & Sealer
Deck stain & sealers generally require the wood to be dry before application, either to allow an oil-based stain to penetrate, or to prevent a water-based film stain from trapping moisture. Follow the instructions on the product for best results.
Use a brush to apply the stain in the direction of the grain to the four sides of each piece, as well as the end grain. Brush away any excess stain to prevent drips. Make sure there is adequate time for the stain to cure in a dry location before assembly.
Prime & Paint
Painting can be done before or after assembly, altho some areas are hard to reach on an assembled bench.
Chris Duderstadt, the original bench designer recommends two coats of good primer followed by one or two coats of exterior paint. Art or graphics can be added on top, along with a clear coat to protect from graffiti and grime.