ISO 16293-2:2025
(Main)Glass in building — Basic soda lime silicate glass products — Part 2: Float glass
Glass in building — Basic soda lime silicate glass products — Part 2: Float glass
This document specifies dimensional and minimum quality requirements (in respect of optical and visual quality) for float glass for use in building, as defined in ISO 16293-1. This document applies to float glass supplied in stock sizes, oversize, and final cut sizes.
Verre dans la construction — Verre de silicate sodocalcique — Partie 2: Glace
General Information
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Standards Content (Sample)
International
Standard
ISO 16293-2
Second edition
Glass in building — Basic soda lime
2025-04
silicate glass products —
Part 2:
Float glass
Reference number
© ISO 2025
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ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Dimensional requirements . 3
4.1 Thickness .3
4.1.1 General .3
4.1.2 Tolerances .3
4.2 Length, width and squareness .4
4.2.1 Stock sizes .4
4.2.2 Final cut sizes .4
5 Quality requirements . 4
5.1 General .4
5.2 Methods of observation and measurement .5
5.2.1 Optical imperfection .5
5.2.2 Visual blemish .6
5.2.3 Edge imperfection for final cut sizes .6
5.3 Acceptance levels .7
5.3.1 Optical imperfections .7
5.3.2 Spot blemish .8
5.3.3 Linear/extended blemish .8
5.3.4 Edge imperfection for final cut sizes .8
6 Designation . 9
Annex A (informative) Method for measuring the halo size of spot fault .10
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
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Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 160, Glass in building.
This second edition cancels and replaces the first edition (ISO 16293-2:2017), which has been technically
revised.
The main changes are as follows:
— introduction of thin glass (under 2 mm);
— revision of defect description and table link with the thickness definition.
— revision of method for measuring the halo size of spot fault.
A list of all parts in the ISO 16293 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
International Standard ISO 16293-2:2025(en)
Glass in building — Basic soda lime silicate glass products —
Part 2:
Float glass
1 Scope
This document specifies dimensional and minimum quality requirements (in respect of optical and visual
quality) for float glass for use in building, as defined in ISO 16293-1.
This document applies to float glass supplied in stock sizes, oversize, and final cut sizes.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 16293-1, Glass in building — Basic soda lime silicate glass products — Part 1: Definitions and general
physical and mechanical properties
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 16293-1 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
length
L
dimension of the straight edge of the glass parallel to the direction of draw of the glass ribbon
Note 1 to entry: See Figure 1.
Key
l direction of draw
L length
W width
Figure 1 — Relationship between length, width and direction of draw
3.2
width
W
dimension of the edge of the glass perpendicular to the direction of the glass ribbon
Note 1 to entry: See Figure 1.
3.3
stock sizes
glass sizes that are intended to be re-cut to obtain final cut sizes (3.4)
Note 1 to entry: Stock sizes can be jumbo sizes (3.3.1), split sizes (3.3.2) or supplied sizes (3.3.3).
3.3.1
jumbo sizes
glass delivered in the following sizes:
nominal length L: 4 500 mm, 5 100 mm or 6 000 mm;
nominal width W: 3 210 mm;
the minimum length of jumbo is 3 600 mm
Note 1 to entry: The usual width is 3 210 mm. Exceptional production requirements can be modified.
Note 2 to entry: The usual maximum length is 6 000 mm. Oversize plates where the nominal length, L, is greater than
6 000 mm can be produced to special order.
3.3.2
split sizes
glass delivered in the following size ranges:
nominal length L: 1 000 mm to 2 550 mm;
nominal width W: 3 210 mm
Note 1 to entry: The usual width is 3 210 mm. Exceptionally production requirements can be modified.
3.3.3
supplied size
pane of glass that has been supplied as raw material for cutting down to a size for installation, delivered in
the following size ranges:
nominal length L: any;
nominal width W: <3 210 mm
Note 1 to entry: In some cases, nominal width can be L < 3 810 mm.
3.4
final cut size
pane of glass that has been cut down to the dimensions being required either for installation or processing
into a final product (such as insulating glass unit or thermally toughened safety glass) of those dimensions
Note 1 to entry: The minimum final cut size usually has dimensions L or W not less than 100 mm and a minimum
surface area of not less than 0,05 m .
3.5
optical imperfection
distortions in the appearance of objects observed through the glass
Note 1 to entry: In other ISO standard on glass in building, imperfection is referred to as defect or fault.
3.6
visual blemish
imperfection that alters the visual quality of the glass
Note 1 to entry: Visual faults include spot blemish (3.7) and linear/extended blemish (3.9).
3.7
spot blemish
imperfection in the glass having a limited size and being composed of a nucleus, which can be accompanied
by a halo (3.8) of distorted glass
3.8
halo
area of glass locally distorted, generally around a nucleus
3.9
linear/extended blemish
imperfection which can be on or in the glass, in the form of deposits, marks or scratches that occupy an
extended length or area
3.10
edge imperfection
imperfection which can occur on the edge of a glass sheet in the form of chips, corner break, beaks, and bevels
Note 1 to entry: See chips in Figure 5, corner break and beaks in Figure 4, and bevels in Figure 6.
4 Dimensional requirements
4.1 Thickness
4.1.1 General
Thickness measurement shall be done by an online or offline measurement system with a precision of
0,01 mm.
For off-line measurement, the thickness shall be the average of four measurements, taken to the nearest
0,01 mm, each one taken at the centre of each side.
4.1.2 Tolerances
All four measurements, rounded to the nearest 0,1 mm, shall not vary from the nominal thickness by more
than the tolerances shown in Table 1.
For the thicknesses not described in Table 1, the tolerance of the nominal thickness immediately lower
shall apply.
Table 1 — Tolerances on nominal thickness
Nominal thickness Tolerances
e
mm mm
e < 2,0 ±0,1
2,0 ≤ e < 3,0 ±0,2
3,0 ≤ e < 8,0 ±0,3
8,0 ≤ e < 12,0 ±0,6
12,0 ≤ e < 19,0 ±0,8
19,0 ≤ e ±1,2
4.2 Length, width and squareness
4.2.1 Stock sizes
The tolerances on nominal dimensions length, L, and width, W, for stock sizes are ±5 mm.
The limits of squareness are described by the difference between diagonals. Limits are given in Table 2.
Table 2 — Limit on the difference between diagonals for jumbo and split sizes
Dimensions in millimetres
Limit on the difference between diagonals
Nominal thickness
Split sizes
e
Jumbo sizes
(L, W) ≤ 1 500 1 500 < (L, W) ≤ 3 000 (L, W) > 3 000
e ≤ 6,0 10 3 4 5
6,0 < e < 15,0 10 4 5 6
15,0 ≤ e 10 5 6 8
4.2.2 Final cut sizes
The tolerances on nominal dimensions length, H, and width, B, for supplied and final cut sizes are given in
Table 3.
The limits of squareness
...
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