Preventing graffiti on a street bench comes down to two things: making the surface difficult to tag and making any tags easy to remove quickly. Yes, there are special coatings I recommend, and they fall into two main categories.
First, sacrificial anti-graffiti coatings. These are usually wax-based or acrylic-based clear coats that form a thin protective film. When someone tags the bench, you simply wash away the graffiti with hot water or a mild solvent—the coating comes off with the paint, taking the graffiti with it. Then you reapply the coating. This is cheap and works well for low-traffic benches or historical surfaces where you don't want a permanent chemical bond. However, you'll need to reapply after every cleaning, so it's higher maintenance over time.
Second, permanent (non-sacrificial) anti-graffiti coatings. These are typically two-part polyurethane, siloxane, or fluoropolymer systems. Once cured, they create a hard, slick barrier that spray paint and markers can't penetrate. To remove graffiti, you use a dedicated graffiti remover or pressure washer, and the bench surface stays untouched. For a street bench exposed to weather and constant sitting, I'd go with a permanent coating—especially an aliphatic polyurethane or a siloxane-based product. Brands like Sherwin-Williams Anti-Graffiti, PPG's PSX 700, or Rust-Oleum's anti-graffiti systems are solid choices, but any commercial-grade product rated for exterior metal or wood will work.
Before applying any coating, prep the bench thoroughly: remove all dirt, rust, and old paint, then prime if needed. Apply two thin coats rather than one thick coat, and let it cure for the full time on the label (usually 24–72 hours). Avoid regular paint—most spray paint will soak into it and become nearly impossible to remove without damaging the bench.
Beyond coatings, a few habits help a lot. Clean off any graffiti within 24–48 hours—taggers lose interest when their work doesn't last. Choose darker or textured surfaces, which are less inviting for tags. And if the bench is in a problem area, add motion-activated lighting or reposition it where there's more foot traffic and natural surveillance.
So yes, a special coating is absolutely worth it. For a street bench, I recommend a permanent anti-graffiti coating like a two-part polyurethane or siloxane system, paired with fast cleanup. It'll save you time and money compared to repainting every few weeks.