Great question. On our wooden outdoor benches, we use a plant-based hardwax oil instead of conventional polyurethane, varnish, or epoxy. The finish is a blend of natural linseed oil and tung oil, thickened with carnauba wax and beeswax. It is low-VOC, solvent-free, and contains no petroleum-derived resins or heavy-metal driers.
We chose this finish for two reasons: performance and environmental impact. Outdoors, wood expands and contracts with temperature and humidity changes. A thick synthetic film can crack, peel, and trap water inside the grain. A natural oil-and-wax finish penetrates the wood, allowing it to breathe and move naturally. It also keeps the surface repairable. If a spot wears thin, you can clean the area, lightly sand it, and apply more oil without stripping the entire bench.
From an eco-friendly standpoint, the ingredients are biodegradable and much safer for garden soil, plants, pets, and the person applying the finish. Because it is low-VOC and solvent-free, it does not off-gas the way solvent-based outdoor finishes do. The oils come from renewable plant sources, and the waxes are naturally derived.
The trade-off is that an oil-and-wax finish is not a high-gloss plastic coating. It gives a soft matte or satin sheen and builds a subtle patina over time. Maintenance is simple but not zero: we recommend cleaning the bench once or twice a year and reapplying a thin coat when water stops beading on the surface. In practice, that usually means once a year for exposed benches.
So yes, the finish we use is eco-friendly. It protects the wood without sealing it in plastic, and it keeps the bench easy to care for over a long outdoor life.