Add cornstarch to clear polish to get matte finish; easier than paying so much for matte nail polish! -- Corn starch is a secret ingredient for painters of all kinds. Pour a bit of your nail polish color of choice onto a piece of wax paper or foil, and add just a pinch of corn starch to the paint. Mix with a toothpick and apply to your nails how you normally would! The finish will be flat and shine-free, very trendy, and you won’t have to buy an extra top coat or special polish.