If your wooden floor has acquired a grey tinge even though it has just been washed, it may be because when washing the floor you rinse the cloth or mop in water that is not clean. This can lead to dirt being spread all over the wooden floor, which may take on a grey tinge. A simple way to get round this problem is by using two buckets when you clean your floor - one with clean, soapy water, and another for wringing the water out of your cloth of mop.