How To Prepare a Wet Mount? The purpose of the wet mount is to check for the cell's motility and the cell's size. Put on gloves and eyes glasses. Take out the slide from the box. The coverslip is needed. • When the starting material is a liquid, use a dropper to take a liquid and place it on the center of the slide. • Take the coverslip at an angle of 45 degrees, touch the slide and drop it to cover the liquid.