The durability test setup was made by putting a rubber eraser (or a water-wet Kimwipe) under a 100 g weight and was placed over a spray-coated microscope glass slide (see Figure ). A swipe was done by pulling the glass slide out of the weighted setup. The setup was then repositioned over the glass slide again to repeat for 100 times. The retained concentrations of Cu, Ag, and Zn were solved following this equation: