What are the standard available thicknesses of float glass under IS 14900?

The standard nominal thicknesses are 2, 3, 3.5, 4, 5, 6, 8, 10, 12, 15, and 19 mm (Clause 5.1).

What is the permitted thickness variation for a 6 mm sheet of glass?

The tolerance is ± 0.2 mm, meaning the actual thickness can range from 5.8 mm to 6.2 mm (Table 2).

How is the quality of float glass checked for visual defects?

Glass is checked for defects like bubbles, scratches, and deposits, which are classified and limited based on their size, quantity, and location (central vs. edge zone) as per Table 1 and Annex A.

Does this standard cover tinted or coated glass?

No, this standard is specifically for transparent (clear) float glass. Tinted and coated glass are covered by separate standards.

IS 14900

: 2018

Transparent Float Glass

CurrentFrequently UsedSpecificationBIMArchitectural · Doors, Windows and Shutters

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This standard specifies the requirements, dimensional tolerances, and test methods for transparent float glass. It serves as the primary quality benchmark for unprocessed float glass used in architecture, furniture, and automotive applications, covering aspects like optical clarity, visual defects, and physical dimensions.

Specifies requirements for transparent float glass for general applications, including building glazing.

Quick Reference Values

Visible light transmittance for 4mm clear glassNot less than 87 percent

Tolerance on nominal thickness for 4mm glass± 0.2 mm

Tolerance on nominal thickness for 12mm glass± 0.3 mm

Maximum bow for cut size glass0.3 percent of the length of the edge

Standard nominal thicknesses available2, 3, 3.5, 4, 5, 6, 8, 10, 12, 15, 19 mm

Practical Notes

The standard differentiates between defect acceptance criteria for the central zone (main viewing area) and the edge zone of a glass sheet, as detailed in Annex A.

Always account for the specified thickness tolerances (Table 2) in the design of glazing channels, frames, and gaskets to ensure a proper fit.

This code is for the base float glass. Any further processing like tempering, heat-strengthening, or laminating must conform to other relevant standards like IS 2553 (Safety Glass) or IS 16700 (Laminated Glass).