That's an excellent and very practical question! The short answer is yes, a traditional wooden bench with a smooth, worn, or glossy finish can become quite slippery when wet. Water acts as a lubricant on that smooth surface, reducing friction. However, this doesn't mean you have to give up on your dream of a beautiful wooden bench. The slipperiness depends heavily on the wood's texture and, most importantly, its finish.
A naturally rough-sawn or deeply grooved wood surface will provide more grip than a planed, sanded-smooth one. The real game-changer is the treatment. A high-gloss varnish or polyurethane, while protective, creates a very slick film when wet. On the other hand, a penetrating oil (like teak or linseed oil) or a specially formulated non-slip deck sealant protects the wood while maintaining more of the natural grain texture for better traction.
For existing slippery benches, don't worry—you have fixes! You can lightly sand the seating area to roughen the finish, apply adhesive non-slip strips or pads designed for outdoor use, or use a brush-on anti-slip coating. For ultimate safety, always make a habit of wiping down the bench with a towel after rain or dew, and consider adding a fitted, textured outdoor cushion.
So, while a wet wooden bench *can* be a slip hazard, with the right choice of wood, a proper non-slip finish, or simple add-on solutions, you can safely enjoy its timeless look in any weather.