Facts are facts; the sun's UV rays cause damage and fading to fabrics. There are a multitude of fabrics that are used for outdoors and each has its performance criteria. We use Polyester in most of our covers. Polyester is soft, pliable and is a relatively durable fabric which isn't industrial in nature. Nonetheless, all fabrics are susceptible to sun damage. Fabrics that are "Solution Dyed" will hold up against fading from UV much better that traditionally dyed fabrics, however, they are much more expensive to make and the manufacturing process is more complex and less environmentally friendly than traditional dying. We use both in our covers for specific reasons, the key reason for using it is simply based on customer demand for "covers that don't fade". These are typically marine grade polyester fabrics. Patio furniture covers made of quality Polyester without "solution dying" will perform well to protect your furniture from UV, rain, etc., but in return for good value they might fade a bit. That's ok as long as the fabric lasts a decent amount of time. Keep in mind it is the furniture you want to maintain that pretty look not the covers.