When sourcing cotton thread in bulk, you must prioritize Yarn Count (e.g., 40s/2, 20s/3), which determines thickness and strength. Ensure the thread is made from 100% Long-Staple Cotton to minimize lint and breakage. For industrial applications, verify the Tensile Strength (cN) and Elongation at Break to ensure compatibility with high-speed sewing machines. Additionally, check for Mercerization, which increases luster and dye affinity, and ensure the thread is Singed (Gassed) to remove surface fuzz for a smoother finish.