Rough and Smooth is a card‐magic principle in which selected cards are treated with a lacquer so that pairs lightly adhere or separate on demand, enabling hidden selections, controls, and reveals. Rough and Smooth relies on applying a subtle abrasive finish (such as hairspray) to the card surface such that, under uniform pressure, paired cards remain inseparable, while a slight change in grip causes the same playing cards to split effortlessly. Rough and Smooth finds application in invisible deck routines, locator effects, and self‐working packet tricks by providing the performer with a built‐in mechanical control that requires minimal sleight of hand. Developed from 17th‐century card‐cheating techniques using rosin and diachylon, or daub, the method was refined for magic by innovators such as Johann Hofzinser and Ralph W. Hull. Today, magicians employ modern spray formulations like Krylon 1311 to create gaff decks that marry chemical preparation with performance art.