Window cleaning
Windows are usually made from glass or plastic, so that light can enter the room during the day. However, after a period of time, dust accumulates on the window panes, reducing the amount of light allowed . If the dust is mixed with water, a thick coat is formed, which prevents light from passing through and the room remains dark even though it is very bright outside.
The best solution is to simply remove the window panes and dip them in water. However, this may not be feasible, if the windows are inconveniently located. If no water has been sprayed, the accumulated dirt can simply be dusted off.