We study the viscous behavior of glass composites with respect to type of filler, filler size, distribution, and interaction between the matrix and filler for industrial applications. Here, the viscosities of the composites were analyzed as a function of the type/size of the fillers (up to 20wt% of Al2O3, ZnO, and TiO2) in a glass (Bi2O3B2O3ZnO) matrix. The particle size was varied from 1 to 10 mu m, which influenced the fluidity of the glass matrix in the composite. Characterizations of the composites were carried out by dilatometry, differential thermal analysis, hot-stage microscopy, and scanning electron microscopy. Fillers having the same particle size as that of the parent glass showed better fluidity behavior. With higher filler content, the filler plays no role in the composite's behavior, whereas a lower to medium amount of filler plays a significant role in the composite's behavior. Fillers with smaller sizes than those of the glass matrix show good dispersion throughout the matrix but agglomeration was observed in some areas.