Surface Compatibility: Standard thumb tacks are designed for corkboards, drywall, and soft wood. They may struggle to penetrate dense materials and can damage walls or leave noticeable holes.
Safety: Because they are sharp and small, they pose a potential choking hazard and a physical hazard if dropped (as they can land point-up).
Durability: Look for nickel-plated or high-quality steel tacks if you need rust resistance, especially for long-term use in humid environments.