To suppress yellow coloring with a silver colloid without polishing surface by regulating the contents of Na2O, K2O and Li2O to specific values or above, regulating specific gravity to a specified value or below and providing a float glass having a specified absorbance.
This float glass is obtained by regulating the sum total of the contents of NaO, K2O and Li2O to ≥5 wt.%, the specific gravity to ≤2.7 at 20°C and ≤0.08 absorbance calculated by A=-log10(T/Tref) based on the transmittance Tref at 410 nm wavelength of the float glass before carrying out silver treatment and the transmittance T at 410 nm wavelength of the float glass after conducting the silver treatment. The silver treatment comprises coating the surface on the side without contact with a molten tin in a float bath with a silver paste containing silver particles, an organic solvent and a resin, baking the coated paste at 580°C for 1 h in the atmosphere, forming a film having ≥10 μm thickness and ≥95 wt.% silver content and removing the film with nitric acid.
MAEDA TAKASHI
NAKAO YASUMASA
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