In this study, differences in the surface composition of commercial glass fiber have been characterized as a function of process. The two processes studied were flame attenuation, a high-temperature combustion-assisted process, and continuous filament drawing through a bushing. The techniques used to determine the surface compositions were TOF-SIMS and XPS; the presence of a very thin, boron-depleted silica-enriched layer on the flame-attenuated fibers was most significant. Thermodynamic modeling of the equilibrium vapor pressures at the surface, during fiberization, showed significant differences in the behavior of Na, B, and F species in the two processes. To further test the models, glass fibers were produced under more closely controlled conditions in a laboratory-scale flame attenuation system. These experiments verified the important effect of flame temperature and residence time in creating the surface layer.