The SUnbrella link that IWillRV2 posted contains the following:
If you forget just google Sunbrella and they have all the washing instructions, stainremoval charts and retreatment advise listed.
Heavy cleaning for stubborn stains and mildew
Sunbrella Shade fabric does not promote mildew growth, however, mildew may grow on dirt and other foreign substances that are not removed from the fabric. To clean mildew, or other stubborn stains:
- Four ounces (1/2 cup) of chlorine bleach.
- Two ounces (1/4 cup) of mild soap and/or detergent.
- One gallon of water.
- Carefully clean with soft bristle brush.
- Allow mixture to soak into the fabric for up to 15 minutes.
- Rinse thoroughly until all soap residue is removed.
- Air dry.
- Repeat if necessary.
- Re-treatment of fabric for water and stain resistance will be necessary.
Sunbrella and most synthetics are not affected by bleach - the soak time is a real key and just be sure to rinse well.
Another tick that 303 Fabric Guard recommends is to do the retreatment on hot sunny for best results. Sunbrella & other synthetics will shrink if heat excessively (100 F is safe).