Blutter coat is an external layer of resin that is applied over the reinforcing structure of a base material. This process involves flow coating the material onto the board and is commonly used for low volume applications, finishing, and repair purposes. The finish of a Blutter Coat may not meet high cosmetic standards and can be susceptible to defects such as the formation of bubbles. The thickness of the coating also tends to vary, with skilled operators typically achieving a more consistent application.