Float Glass: Why Modern Windows Ride on Molten Tin

Most modern windows begin as a continuous ribbon of molten glass floating on liquid tin. Follow sand, soda ash, limestone, and recycled cullet through a hot furnace, the float bath, controlled cooling, optical inspection, and cutting, and learn why this process replaced costly grinding and polishing. Inside this episode: - Flat glass before the float process - Melting and refining the raw batch - Why molten glass spreads smoothly across tin - Controlling ribbon thickness and relieving stress - Inspection, cutting, recycling, and downstream finishing Sources include Pilkington and NSG process documentation, United States EPA glass-manufacturing records, and United States International Trade Commission reporting. This episode is a researched narrative summary. Historical records may be incomplete, translated differently, or interpreted differently by scholars. We distinguish documented facts, estimates, disputed interpretations, and later stories where material. Corrections are logged and incorporated into future editions. Follow Inside the Manufacturing Process for more journeys through the factories behind modern life.