Cleaning canvas takes extra care and the use of organic cleaners to prevent drying and damage. Clean canvas by mixing one half cup hydrogen peroxide or ¼ cup Borax to three tablespoons of organic laundry detergent mixed in a quart of water. Apply wait 15 minutes then rinse and allow to air dry. Repeat if needed and wait 30 minutes. Always test a small area first for color fading as borax can take the color out of fabrics.