When evaluating glass silk, you must prioritize the filament diameter (measured in microns) and the tex (linear density). For high-end electronics or filtration, a smaller diameter provides better flexibility. Ensure the material is categorized correctly as E-glass (electrical grade) for general insulation or S-glass (high strength) for aerospace and structural applications. Additionally, verify the tensile strength and alkali content, as these directly impact the material's durability in harsh environments.