Film fragmentation (FF) stands as a well-recognized disintegration mode renowned for its substantial throughput in droplet or particle production facilitated by rotary disk atomizers. Despite its prominence, a dearth of comprehensive information persists regarding the FF mode, particularly regarding the potential influence of viscosity on FF characteristics. Our study undertakes experimental investigations utilizing glycerol/water as the working fluids to elucidate FF characteristics across a spectrum of viscosities. The film and droplet metrics were systematically evaluated at various viscosities. Empirical relationships were established to estimate the FF characteristics with cross-validation against other works. Our findings underscore the stabilizing influence of high fluid viscosity on the liquid film, facilitating its complete development and contributing to the maintenance of a diminutive D32 across a broad flow spectrum. This research yields pivotal theoretical insights pertinent to the centrifugal atomization of relatively high viscosity fluids, offering pathways for achieving substantial throughput in atomization processes.