That's an excellent and very practical question! Yes, in most quality outdoor benches, the wooden slats are indeed treated to prevent splintering and withstand the elements. However, the type and effectiveness of the treatment can vary greatly.
Typically, the wood is either pressure-treated with preservatives or sealed with a protective finish. Pressure-treated wood is infused with chemicals that resist rot, insects, and moisture, which inherently helps prevent the splintering caused by decay. For hardwoods like teak or cedar, a natural oil or a protective sealant (like a UV-resistant outdoor oil or varnish) is often applied. This coating creates a barrier against water absorption and sun damage, the two main culprits that cause wood to dry out, crack, and eventually splinter.
It's crucial to note that no treatment is permanent. To reliably prevent splintering, regular maintenance is key. This includes annual cleaning and reapplication of a protective sealant as recommended. Always check with the manufacturer of your specific bench for their treatment specifications and care guidelines. If you're building a bench yourself, treating the wood before assembly is a non-negotiable step for long-term safety and durability. So, while the initial treatment is a great start, your ongoing care is what truly keeps those slats smooth and splinter-free for years to come.