The use of Brush Seals continues to expand in both the Power Generation and the Aerospace markets; being applied to more demanding locations and operating environments. Over the last 35 years, much has been learned about brush seal functionality and detailed design procedures and codes have been developed and refined. This information is used in the feasibility of brush seal applications and in establishing an optimized design for the given application. This paper is an introduction to elements of the design process, engineering principles, and the current state of the art used at Cross Manufacturing Co (1938) Ltd.