In Fahrenheit 451, Bradbury often employs colours in order to convey a particular idea about a scene, a location or a character. This is the strategy that he employs in this case as well.
When Montag reads while Mildred stares blankly at the parlor on a cold afternoon, Bradbury describes the scene in grey colors. On the other hand, when describing how Montag met the old man years ago, the scene is described in dark colors. In this book, dark colors are used as symbols to describe unpleasant situations.
