Many man-made fabrics are well suited for outdoor usage. Polyester is a lightweight fabric that retains its vibrant dyes over time. Polyurethane is a chemical used in many products to create a protective coating or finish. When polyester is treated with polyurethane, it makes the fabric waterproof. Waterproof, lightweight fabric is highly suited for patio umbrellas. Polyurethane-coated polyester patio umbrellas are flammable and shouldn't be used near candles, such as citronella candles.
Acrylic is another synthetic fabric with waterproof properties. Outdoor acrylic is dyed with chemical dyes to retain color when exposed to outside elements. Lightweight and long-wearing, acrylic is often treated with ultraviolet-resistant chemicals to eliminate fading. Good Housekeeping suggests acrylic fabric treated with both mildew-resisting additives and with high ultraviolet ratings for use in outdoor patio umbrellas. Acrylic is available in fabric widths of 46 and 60 inches wide and is sold from the bolt for sewing your own patio umbrella rather than purchasing a ready-made choice. Don Vandervort's Home Tips website maintains that acrylic patio umbrellas maintain their usefulness for about 10 years with proper maintenance, such as washing the umbrella with liquid dish detergent and off-season indoor storage.
Canvas is sometimes referred to as cotton duck or painted duck fabric. Waterproofing additives are sometimes used to prolong the durability of canvas fabric, but the best type of canvas for patio umbrellas is painted duck. Painted duck is canvas treated with an acrylic paint solution which, according to Don Vandervort's Home Tips website, fares even better than a canvas umbrella with waterproofing applied. Painted duck will typically last for about eight years when properly maintained. Uncoated canvas will mildew if not properly cared for but is strong enough to withstand cleaning. Store canvas patio umbrellas in a covered area during the off-season, or use patio umbrella covers and tarps to provide shelter from the elements.