For school playgrounds, our outdoor bench factory strongly recommends heat-treated wood or a light-colored HDPE composite. Heat-treated wood, such as thermo-ash, robinia, or teak, has low thermal conductivity. It does not trap and release heat like metal or dark plastic. Even after hours in direct summer sun, its surface stays warm but not burning. Choose a light natural tone or a pale finish; dark colors absorb more solar heat. We also suggest an open-slat design for airflow and a non-toxic, matte outdoor oil. If you want recycled plastic, pick a light gray or sand-colored HDPE composite rather than black or dark brown. Metal frames should be powder-coated in a light color and kept away from direct skin contact. Finally, place benches under shade sails, trees, or a covered area. This combination keeps children safer and more comfortable.