Bowling lanes are coated with carefully applied oil patterns that aren't meant to reduce friction between the ball and lane, but rather to control how much the ball hooks and curves toward the pins. Professional bowlers study these invisible oil patterns like golfers read greens, because the oil wears away during play and completely changes ball behavior as games progress. A typical bowling center applies fresh oil using computerized machines that can lay down over 40 different sanctioned patterns, from easy "house shots" for casual players to wickedly difficult "sport patterns" where oil is distributed more evenly. The oil used is specifically formulated to be stable under the pounding of 15-pound balls traveling at 20 mph, while also being safe to breathe since it creates a fine mist in the air around the lanes.