In this study, the effects of metallic zinc (Zn) particles were studied to increase surface temperature on a solar-still absorber, which is a major component of increased production. Various concentrations of Zn particles were mixed in black paint and applied to the absorber plate. SEM and XRD were used to examine and confirm the surface morphology and phase identification of as-received powder. UV-Vis spectroscopy was used to examine light-absorption properties. Finally, extensive indoor testing (using an improvised solar emulator) and outdoor testing were conducted to optimize the concentration. The specimens containing 10 wt% Zn in black paint showed the highest increase in temperature, i.e., 103.53 °C in indoor conditions at 1000 W/m2 irradiation, which is 59.17% higher than a bare aluminum plate and 17.57% higher than an only black-paint-coated aluminum plate. On the other hand, specimens containing 10 wt% Zn reached just 87.53 °C, compared to 80.00 °C for an only black-paint-coated aluminum plate and 60.62 °C for bare aluminum.