You should clean your door and window frames at least once a year.
If your home is near the sea or an industrial area, you will need to clean your frames more often. You should keep in mind not to damage the operation and appearance of your frames while cleaning them. Ideally, you should use a very soft cloth or sponge, lots of water and a mild cleaning product, such as dish soap.
Attention: Never use gardening hoses or high pressure cleaning equipment.