IS 3618 specifies quartz sand for glass manufacturing. The key requirement is high SiO2 content (>95%) with low iron oxide (<0.1% for clear glass). Three grades based on purity for different glass types.
Specification for quartz sand (silica sand) used as raw material in glass manufacturing, covering chemical composition and grain size distribution.
Key Values
Grade I SiO2 min99.0%
Grade II SiO2 min97.0%
Grade III SiO2 min95.0%
Practical Notes
! Iron content is the most critical impurity — even 0.1% Fe2O3 gives green tint to glass.
! Grade I is for optical and colourless glass. Grade III is for coloured bottles where iron tint is acceptable.
! Grain size affects melting rate — finer sand melts faster but costs more to process.