The right application of waterproofing can prevent mold and mildew from forming on a canvas tarp. Tarps act as protection for boats, lawn mowers or other items which are left out in the elements or stored in cool, damp places. The tarp, if treated properly, keeps dirt and water off the covered items. However, without the proper waterproofing treatment, rain and other moisture sources may begin to penetrate the canvas and allow mold and mildew to form on the tarp.
Spread the canvas tarp, top side up, in a clean, dry area.
Mix a small amount of dish detergent in a bucket of water.
Wash the top of the tarp using a clean cotton rag and the detergent mixture. Rinse with fresh water and allow to dry.
Spray fluoropolymer-based waterproofing horizontally across the tarp, working from the top downward. Allow the product to sit on the tarp for the amount of time recommended by the manufacturer.
Apply a second coat of the waterproofing vertically across the tarp, working from left to right. The checkerboard application assures that all points are covered. Allow the tarp to dry completely before using.