Teak is a very strong, weatherproof material which gains a natural patina over the course of time (a thin, silver-gray coating). This patina can be cleaned off with a scouring pad and a little hot water if required. If you would like to maintain the original coloration of the wood, when it is dry, you can treat the wood with teak oil (available at most DIY stores). You can leave untreated teak sunshades outside in the winter. Teak sunshades that have been treated with teak oil, however, should be kept under cover. In both cases, GLATZ recommends covering the sunshade fabric with a GLATZ protective cover.