Depending on the design of the drum dryer, the product is applied continuously as a thin film on the underside or top of the main drum. As the drum turns and is heated on the inside, the product dries on the outside of the drum dryer. The short exposure to a high temperature reduces the risk of damage to the product. The water or solvent evaporates and leaves the process at thetop. If necessary, the vapour can also be suctioned off locally around the drum. The dried product layer finally reaches the knife and is scraped off