Find out if your furniture is fine sanded or oiled. Sanded teak has a natural, light yellow-brown color and raw texture. Because it is untreated, when exposed to sunlight and the outdoors, it will age to a silvery gray over time---a desired effect. It needs no treatment except occasional cleaning.
Clean teak that has been left outside with a soft or medium brush and mild soapy water. Use a wood cleaner, such as Murphy's Oil Soap, or a product recommended by the teak furniture manufacturer. Rinse with clear water. For stains, such as bird deposits or accumulated dirt, there are specially developed cleaners you can use. Harsh steel wool pads or high-pressure hosing is not recommended. Sand stubborn stains with a fine-grade sandpaper and stroke lightly in the direction of the grain.
Dry any metals on the furniture---but they should not rust because of the teak.
Wait for the teak to dry before oiling---overnight is best.
Lay newspaper under and around the furniture. Apply teak oil with a clean brush, starting from the top of the furniture and working your way down. Let the oil soak in for five to 10 minutes. Wipe the furniture down with clean rags, removing the excess. Buff with a second rag after the surface is dry.
Oil furniture to help maintain its golden appearance. Pre-oiled teak has a darker brown coloring than the sanded type. Using oil does not add to the furniture's lifespan, but might prevent stains from leaching into the grain. Oiling will also slow graying because of its protection against the sun's UV rays.
Store teak furniture, covered with special weather tarp, during winter or move the furniture to a sheltered area.