Our test sample of Sunbrella was left for a year in a position that caused it to catch and maintain the morning dew. The location was shady. Without care and without the sun's drying and bleaching qualities, what resulted was the worst patch of mold and mildew we’d ever seen on canvas.
We applied Star brite Sail and Canvas cleaner. How did it do? The top half of the above picture is the section we didn’t clean. The bottom half received two applications of Sail and Canvas Cleaner with a stiff brush. As the picture shows, it did a great job, cleaning the mung and leaving the color of the fabric. Star brite Sail and Canvas cleaner did “spot” (actually, clean) and streak the faux-wood planked dock upon which it dripped as we performed the cleaning test. So be careful to cover porous surfaces and fabrics below your cleaning area.