Know the wicker. Wicker encompasses various materials used by different manufacturers to make what is known as "wicker" furniture. These materials include reed, rattan, willow -- straight fibers -- as well as twisted fibers. Twisted fibers shouldn't be hosed or stripped.
Clean the wicker. For straight-fiber wicker, a light shower from a hose will clean and exercise the furniture fibers to aid their resilience and prep them for resisting the elements. Allow the wicker to dry in the shade before placing it in the sun. Use a soft brush, such as a toothbrush, to remove dirt in especially hard-to-reach areas.
Prepare for weatherproofing. Brush liquid sanding fluid on the wicker for removal of grease and grime. The fluid also softens old paint, and will help the weatherproofing compound to bond better to the wicker.
Spray on weatherproofing. Spraying works best. Some paint brands make clear-finish weatherproofing products that work well with wicker. Observe directions on the can and work in a well-ventilated area. Brush-on weatherproofing is also available, if you prefer.
Be realistic. Cathryn Peters, an expert wicker weaver, asserts that weather will eventually rot wicker fibers, no matter how strong the weatherproofing product. She concedes, however, that weatherproofing does prolong wicker life. Further, weatherproofing chemicals are toxic and potentially harmful to the environment. Avoid them if sensitive to chemicals or ecological ethics.