Things You'll Need
Soft-bristled brush or broom
Spray-on water repellent
A polyester canopy serves as a protective cover for your outdoor event or space. It can block protect you and your guests from the weather, including intense sun, rain or wind. Waterproofing the canopy is an important step for maintaining its functionality. Luckily, waterproofing is a simple process and requires few materials.
Remove the polyester canopy top carefully from the frame. If it has sides that attach to the frame, remove them first. These can be waterproofed as well if desired, but it is not necessary as water will generally drip down the side pieces.
Lay the polyester canopy out on the grass or a smooth surface. Be sure there are no sharp objects or rocks beneath the canopy that could tear or snag the material. Also keep in mind any surface you use may collect run-off spray from the waterproofing product.
Clean the canopy by brushing away dust and dirt with the brush or broom. If dirt or any stains remain, you may wash the canopy with the garden hose and use the brush to gently scrub away any stubborn spots.
Dry the polyester canopy in the sun thoroughly if you wash it or it has any moisture in the fabric.
Spread the polyester canopy carefully so it has no creases or folds. Spray the fabric with the waterproofing agent according to the instructions on the can. You may need to shake the product and be sure to maintain the recommended distance for spraying listed on the can. It is best to hold the can at a 45-degree angle. It is also not advisable to do this on a breezy day as your spray will dissipate in the air or could be blown around the canopy in an uneven pattern. Spray in a consistent pattern, beginning at one corner and working up or down in sections until you reach the other edge. Repeat until the entire canopy is covered. Use a slight sweeping motion to be sure the spray is spread evenly and not applied too heavily.
Let the polyester canopy dry thoroughly. Apply another coat if desired. Replace the canopy on the frame once it has dried.