Start by identifying what caused the stain and test any cleaner on a hidden area first. For everyday dirt, mix a few drops of mild dish soap with warm water, scrub gently with a soft nylon brush or microfiber cloth, then rinse with clean water and dry with a soft cloth. Avoid steel wool, abrasive pads, acetone, and harsh bleach-based cleaners, because they can dull or damage the composite surface. Also skip high-pressure washing, which can force water into seams and edges.
For greasy or oily marks, use a small amount of dish soap or a composite-safe degreaser. Let it sit for three to five minutes, scrub lightly, and rinse thoroughly. For chewing gum, harden it with ice, then lift it with a plastic scraper—never a metal tool. Mildew often responds to a diluted white vinegar solution or a mild outdoor cleaner labeled safe for composite material; scrub, rinse, and let the furniture dry completely. Rust marks may need an oxalic acid-based cleaner used strictly according to the label and tested first.
After cleaning, wipe the furniture dry and remove standing water from joints. For urban outdoor furniture, a quick weekly wipe-down and prompt cleanup of bird droppings, coffee spills, and tree sap will prevent most stains from setting. If the manufacturer recommends a protectant, use only a non-abrasive product made for composite outdoor furniture, and follow the label carefully.