Mildew is a common problem that attacks outdoor canvas, whether it is a canvas awning, patio umbrella or set of upholstered patio furniture. The mildew grows quickly once it begins to develop, so you must properly remove the mildew in a way that causes no harm to the canvas.
Causes of Mildew
Mildew is typically caused by excess moisture, including rain, use of the garden hose and similar items. When you have canvas areas that hold excess moisture and are constantly subjected to outdoor weather conditions, the mildew can begin to grow and multiply at a rapid pace.
Preparing for Mildew Removal
Gather your cleaning supplies. Grab a bucket, a hose and a nylon scrub brush. For cleaning, collect a bottle of dish soap and a bottle of white vinegar. The combination of soap and vinegar will thoroughly clean and remove the mildew, and neither will harm the canvas. Use a nylon brush and not a wire brush as the wire can snag and tear the mildew.
Removing the Mildew
Mix 1 gallon of water with about 1 cup of white vinegar and 2 tbsp. of dish soap. Rinse down the mildew thoroughly with the garden hose to remove much of the loose, powdery mildew. Dip your scrub brush into your bucket of cleaning solution, and scrub down the canvas. Clean the canvas using small circular motions, and dip your brush back into the bucket every minute or so. Rinse your canvas thoroughly after cleaning, and allow it to dry in direct sunlight when possible.
Preventing the Mildew
Since moisture is the main cause of mildew growth, do your best to keep the mildew away from the rain and water conditions. Close patio umbrellas and awnings when a rain shower is passing through, and bring patio cushions indoors or store them in a shed when the cushions are not in use, which will greatly reduce the wear, tear and mildew buildup that the canvas receives.