When sourcing float glass, buyers must prioritize optical clarity, thickness tolerance, and edge finish. High-quality float glass should have a thickness deviation of less than ±0.2mm and be free of visible bubbles, stones, or scratches. For structural or safety applications, ensure the glass meets ASTM C1036 (Standard Specification for Flat Glass) or EN 572 standards. Additionally, verify the iron content; 'Clear' glass has a slight green tint, while 'Ultra-Clear' (Low-Iron) glass offers superior light transmission (>91%) and is essential for high-end architectural or display purposes.