1. Deviate, digress, diverge, swerve imply turning or going aside from a path. To deviate is to turn or wander, often by slight degrees, from what is considered the most direct or desirable approach to a given physical, intellectual, or moral end: Fear caused him to deviate from the truth. To digress is primarily to wander from the main theme or topic in writing or speaking: Some authors digress to relate entertaining episodes. Two paths diverge when they proceed from a common point in such directions that the distance between them increases: The sides of an angle diverge from a common point. Their interests gradually diverged. To swerve is to make a sudden or sharp turn from a line or course: The car swerved to avoid striking a pedestrian.

Did you mean undercoating?