oSIST prEN 1748-2-1:2017

Glass in Building - Special basic products - Glass ceramics - Part 2-1: Definitions and general physical and mechanical properties

This European Standard specifies and classifies special basic products - glass ceramics, indicates their chemical composition, their main physical and mechanical characteristics, their dimensional and minimum quality requirements (in respect of optical and visual faults).
This European Standard applies to special basic products - glass ceramics supplied in stock sizes, supplied sizes or in cut sizes for final end use.
This European Standard does not apply to final cut sizes having a dimension less than 100 mm or a surface area less than 0,05 m2.

Glas im Bauwesen - Spezielle Basiserzeugnisse - Glaskeramik - Teil 2-1: Definitionen und allgemeine physikalische und mechanische Eigenschaften

Diese Europäische Norm legt spezielle Basiserzeugnisse aus Glaskeramik fest, klassifiziert diese und macht Angaben über deren chemische Zusammensetzung, wesentliche physikalische und mechanische Eigenschaften, Anforderungen an die Maße und Mindestanforderungen an die Qualität (in Hinsicht auf optische und sichtbare Fehler).
Diese Europäische Norm gilt für spezielle Basiserzeugnisse aus Glaskeramik, die in Standardabmessungen, in Liefermaßen oder in Festmaßen für ihren Verwendungszweck geliefert werden.
Diese Europäische Norm gilt nicht für Glaskeramik mit Festmaßen von weniger als 100 mm oder mit einer Oberfläche von weniger als 0,05 m2.

Verre dans la construction - Produits de base spéciaux - Vitrocéramiques - Partie 1 : Définitions et propriétés physiques et mécaniques générales

La présente Norme européenne spécifie et classe les produits spéciaux de base - vitrocéramiques, indique leur composition chimique, leurs principales propriétés physiques et mécaniques, leurs exigences dimensionnelles et qualitatives minimales (compte tenu des défauts optiques et d'aspect).
La présente Norme européenne s'applique aux produits de base spéciaux - vitrocéramiques fournis en dimensions standard, en dimensions livrées ou en dimensions découpées en mesures fixes en vue de leur usage final.
La présente Norme européenne ne s'applique pas aux vitrocéramiques découpées en mesures fixes en vue de leur usage final dont l'une des dimensions est inférieure à 100 mm ou dont l'aire de la surface est inférieure à 0,05 m².

Steklo v stavbah - Posebni osnovni proizvodi - Steklena keramika - 2-1. del: Definicije in splošne fizikalne in mehanske lastnosti TC: Steklo v gradbeništvu -

General Information

• Status: Not Published
• Public Enquiry End Date: 14-Oct-2017
• ICS: 01.040.81 - Glass and ceramics industries (Vocabularies)
• ICS: 81.040.20 - Glass in building
• ICS: 81.060.01 - Ceramics in general
• Technical Committee: STV - Steklo, svetloba in razsvetljava v gradbeništvu
• Current Stage: 4020 - Public enquire (PE) (Adopted Project)
• Start Date: 28-Aug-2017
• Due Date: 15-Jan-2018
• Completion Date: 14-Nov-2017
• Directive: 305/2011 - Regulation (eu) No 305/2011 of the European Parliament and of the Council of 9 march 2011 laying down harmonised conditions for the marketing of construction products and repealing council directive 89/106/eec
• Mandate: M/135 - Mandate to CEN/CENELEC concerning the execution of standardization work for harmonized standards on flat glass, profiled glass and glass block products
• Ref Project: prEN 1748-2-1 - Glass in Building - Special basic products - Glass ceramics - Part 2-1: Definitions and general physical and mechanical properties

Relations

• Revised: SIST EN 1748-2-1:2004 - Glass in building - Special basic products - Glass ceramics - Part 2-1 Definitions and general physical and mechanical properties
• Effective Date: 18-Jan-2023
• Revised: SIST EN 1748-2-1:2004 - Glass in building - Special basic products - Glass ceramics - Part 2-1 Definitions and general physical and mechanical properties
• Effective Date: 01-Oct-2017

Overview

The European Standard oSIST prEN 1748-2-1:2017:2017 titled Glass in Building - Special Basic Products - Glass Ceramics - Part 2-1: Definitions and General Physical and Mechanical Properties is developed by the Technical Committee CEN/TC 129 “Glass in building.” This standard specifies classifications, chemical compositions, physical and mechanical characteristics, as well as dimensional and minimum quality requirements focused on glass ceramics as special basic products used in construction.

This standard applies to special basic glass ceramic products supplied in stock, supplied, or cut sizes intended for final end use, with minimum dimensions of at least 100 mm and a surface area of 0.05 m². It excludes final cut sizes smaller than these limits.

Key Topics

• Glass Ceramics Definition: Glass ceramics are materials composed of a crystalline phase embedded in a residual glass phase, produced through controlled heat treatment of glass.

• Chemical Composition: The standard details elemental mass proportions including silicon (23-38%), aluminium (7.9-14.5%), lithium, sodium, calcium, magnesium, zinc, potassium, zirconium, titanium, and barium in varying proportions (up to 7.2%), with oxygen unspecified.

• Physical and Mechanical Properties:

  • Density: 2400-2600 kg/m³ at 18°C
  • Knoop Hardness: 600-750 HK (ISO 9385 standard)
  • Young's Modulus: approx. 9 × 10¹⁰ Pa
  • Poisson’s Ratio: 0.2
  • Thermal Characteristics: Zero linear expansion between 20°C and 300°C, resistance to temperature changes up to 650 K, thermal conductivity between 1.5 and 1.7 W/(m⋅K)
  • Refractive Index (589.3 nm): ~1.5
  • Emissivity: 0.837

• Bending Strength:

  • Floated glass ceramics: 45 MPa
  • Rolled glass ceramics: 25 MPa

• Dimensions and Tolerances:

  • Defines stock sizes, supplied sizes, and final cut sizes.
  • Thickness, length, width, and squareness tolerances are specified, with squareness now assessed by diagonal difference.

• Quality Requirements:

  • Optical faults causing distortions
  • Visual faults including spot faults (inclusions, bubbles) and linear or extended faults (scratches, marks)
  • Edge defects such as entrant/emergent faults and bevels
  • Single quality class with defined acceptance levels for faults
  • Revised observation methods including the Zebra method for optical fault identification.

Applications

oSIST prEN 1748-2-1:2017 serves as a fundamental reference for manufacturers, processors, and specifiers of glass ceramics in building applications such as:

• Structural and architectural glazing components where specialized physical and mechanical performance is required
• Heat-resistant or dimensionally stable glass elements in façades, partitions, or fire-resistant applications
• Components requiring precise dimensional tolerances and controlled optical/visual quality for aesthetic and safety standards
• Use in cutting and fabrication processes for final products such as laminated or insulating glass units conforming to specified minimum size requirements

Professionals in glass production, architectural design, construction engineering, and quality control use this standard to ensure uniformity, safety, and compliance with European market regulations.

Related Standards

• EN 1748-2-2: Glass in Building – Special Basic Products – Glass Ceramics – Part 2-2: Product Standard, for evaluation of conformity and product requirements.
• EN 1748-1-1 and EN 1748-1-2: Specifications for Borosilicate glasses as special basic products.
• EN 410:2011: Determination of luminous and solar characteristics.
• ISO 9385:1990: Knoop hardness testing of glass and glass-ceramics.
• prEN 16612: Design of glass panes, including bending strength considerations.
• REACH regulations as referenced in informative annex A, concerning chemical safety and environmental compliance.

By adhering to oSIST prEN 1748-2-1:2017, stakeholders guarantee the quality, reliability, and standardized performance of glass ceramics, supporting innovation and safety in modern building construction.

Standards Content (Sample)

SLOVENSKI STANDARD
01-oktober-2017
Steklo v stavbah - Posebni osnovni proizvodi - Steklena keramika - 2-1. del:
Definicije in splošne fizikalne in mehanske lastnosti
Glass in Building - Special basic products - Glass ceramics - Part 2-1: Definitions and
general physical and mechanical properties
Glas im Bauwesen - Spezielle Basiserzeugnisse - Glaskeramik - Teil 2-1: Definitionen
und allgemeine physikalische und mechanische Eigenschaften
Verre dans la construction - Produits de base spéciaux - Vitrocéramiques - Partie 1 :
Définitions et propriétés physiques et mécaniques générales
Ta slovenski standard je istoveten z: prEN 1748-2-1
ICS:
01.040.81 6WHNODUVNDLQNHUDPLþQD Glass and ceramics
LQGXVWULMD6ORYDUML industries (Vocabularies)
81.040.20 Steklo v gradbeništvu Glass in building
81.060.01 Keramika na splošno Ceramics in general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2017
ICS 01.040.81; 81.040.20; 81.060.01 Will supersede EN 1748-2-1:2004
English Version
Glass in Building - Special basic products - Glass ceramics -
Part 2-1: Definitions and general physical and mechanical
properties
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 129.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations
which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2017 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 1748-2-1:2017 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Chemical composition . 6
4.1 General . 6
4.2 Tint . 7
5 Physical and mechanical characteristics . 7
5.1 General characteristics . 7
5.2 Characteristic bending strength . 8
5.3 Designation of clear glass ceramics . 8
5.3.1 General . 8
5.3.2 Clear transparent glass ceramics . 9
5.3.3 Clear translucent glass ceramics . 9
5.4 Stability of physical and chemical characteristics . 10
6 Dimensional requirements. 10
6.1 Manufacturing dimensions . 10
6.1.1 Stock sizes . 10
6.1.2 Supplied and final cut sizes . 10
6.2 Thickness and thickness tolerances . 10
6.3 Length, width and squareness . 11
7 Quality requirements . 11
7.1 General . 11
7.2 Quality criteria and their evaluation . 12
7.2.1 Optical . 12
7.2.2 Appearance . 12
7.3 Methods of observation and measurement . 12
7.3.1 Optical faults . 12
7.3.2 Visual faults (spot faults, linear/extended faults), all types of glass ceramics . 13
7.4 Acceptance levels . 14
7.4.1 Optical faults . 14
7.4.2 Visual faults (spot faults, linear/extended faults, all types of glass ceramics) . 14
7.5 Edge defects for final cut sizes . 15
7.5.1 Entrant and emergent faults . 15
7.5.2 Bevel . 16
7.5.3 Limitations on edge defects . 16
8 Designation. 16
Annex A (informative) Complementary information related to REACH . 18
Bibliography . 19

European foreword
This document (prEN 1748-2-1:2017) has been prepared by Technical Committee CEN/TC 129 “Glass
in building”, the secretariat of which is held by NBN.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 1748-2-1:2004.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association.
The main changes compared to the previous edition are the following:
a) Clause 1: drawn and casted process have been removed;
b) Chemical composition has been modified in Table 1 to express composition in elements;
c) Clause 5: luminous transmittance have been modified;
d) Clause 6: new thickness tolerances have been added for floated glass ceramics and sub Clause 6.3
“Tolerances and squareness” has been completely revised; the squareness of rectangular glass
panes is now expressed by the difference between its diagonals;
e) Clause 7 has been completely revised (including the Zebra method of observation optical faults);
f) Categories of defects have been removed, only one quality is defined (Table 9);
g) a new informative Annex A given complementary information related to REACH has been added;
h) the document has been editorial revised.
EN 1748 is currently composed with the following parts:
— EN 1748-1-1, Glass in building — Special basic products —Borosilicate glasses — Part 1-1: Definition
and general physical and mechanical properties;
— EN 1748-1-2, Glass in building — Special basic products — Borosilicate glasses — Part 1-2:
Evaluation of conformity/Product standard;
— EN 1748-2-1, Glass in Building — Special basic products — Glass ceramics — Part 2-1: Definitions
and general physical and mechanical properties;
— EN 1748-2-2, Glass in building — Special basic products — Glass ceramics — Part 2-2: Product
standard.
1 Scope
This European Standard specifies and classifies special basic products - glass ceramics, indicates their
chemical composition, their main physical and mechanical characteristics, their dimensional and
minimum quality requirements (in respect of optical and visual faults).
This European Standard applies to special basic products - glass ceramics supplied in stock sizes,
supplied sizes or in cut sizes for final end use.
This European Standard does not apply to final cut sizes having a dimension less than 100 mm or a
surface area less than 0,05 m .
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
EN 410:2011, Glass in building — Determination of luminous and solar characteristics of glazing
ISO 9385:1990, Glass and glass-ceramics — Knoop hardness test
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
glass ceramics
type of glass consisting of a crystalline and a residual glass phase
Note 1 to entry: The glass is obtained by normal glass manufacturing methods, e.g. floating or rolling and is
subsequently subjected to a heat treatment which transforms, in a controlled manner, part of the glass into a fine
grained crystalline phase; the glass ceramics has properties which deviate from those of the glass from which it
was transformed.
3.2
floated glass ceramics
flat, transparent or translucent, clear or tinted glass ceramics having parallel and polished faces
obtained by continuous casting and flotation on a metal bath
Note 1 to entry: In French called 'glace' and in German 'Floatglas'.
3.3
rolled glass ceramics
flat, transparent or translucent, clear or tinted glass ceramics obtained by continuous casting and
rolling
3.4
length, H and width, B
defined with reference to the direction of draw of the glass ribbon as shown in Figure 1
Key
1 → - direction of draw
H - length
B - width
Figure 1 — Relationship between length, width and direction of draw
3.5
stock sizes
glass ceramics delivered in manufacturer's standard stock sizes
3.6
supplied size
pane of glass ceramics that has been supplied either as raw material for further processing and/or
cutting down to a size for installation
Note 1 to entry: This is a size outside the stock size.
3.7
final cut size
pane of glass ceramics that has been cut down to the dimensions being required either for installation
or processing into a final product
Note 1 to entry: Examples of processed final products are insulating glass units or laminated glass of those
dimensions.
3.8
optical fault
fault which lead to distortions on the appearance of objects observed through the glass ceramics
3.9
visual fault
fault which alter the visual quality of the glass ceramics
Note 1 to entry: Visual faults include spot faults and linear / extended faults.
3.10
spot fault
nucleus which is generally accompanied by a halo of distorted glass
Note 1 to entry: Spot fault can be solid inclusions, bubbles, etc.
3.11
halo
area locally distorted, generally around a point defect
3.12
linear / extended fault
fault which can be on or in the glass ceramics, in the form of deposits, marks or scratches that occupy an
extended length or area
3.13
edge defect
defect which can occur on the edge of a cut size piece in the form of entrant and emergent fault and/or
bevel
3.14
concentration
c
sum of the lengths of gaseous inclusions > 1,0 mm in any circle of 400 mm diameter
4 Chemical composition
4.1 General
The special basic products covered by this European Standard are all manufactured from glass
ceramics.
The magnitude of the proportions by mass of the constituents of glass ceramics covered by this
standard is given in Table 1, see also Annex A.
NOTE Oxygen is not mentioned in Table 1 (see Annex A).
Table 1 — Magnitude of the proportions by mass of the constituents of glass ceramics
Constituents Proportion by mass of element
Silicon (Si) 23 % - 38 %
Aluminium (Al) 7,9 % - 14,5 %
Lithium (Li) 0 % - 2,4 %
Sodium (Na) 0 % - 1,5 %
Calcium (Ca) 0 % - 5,8 %
Magnesium (Mg) 0 % - 4,9 %
Zinc (Zn) 0 % - 4,1 %
Potassium (K) 0 % - 1,7 %
Zirconium (Zr) 0 % - 3,7 %
Titanium (Ti) 0 % - 3,0 %
Barium (Ba) 0 % - 7,2 %
a < 5 %
Other components excluding oxygen
a
Properties other than photometric characteristics shall not be significantly altered by these other components
4.2 Tint
Body tinted glass ceramics is obtained by the addition of suitable materials.
5 Physical and mechanical characteristics
5.1 General characteristics
Conventional numerical values for the physical and mechanical characteristics of glass ceramics
excluding ‘Characteristic bending strength (f ) are given in Table 2. These values are not precise
g,k
requirements with which the glass ceramics shall strictly comply, but are the generally accepted figures
for use in calculations where a high degree of accuracy is not required.
Table 2 — Physical and mechanical characteristics of glass ceramics
Characteristic Symbol Value and unit
Density (at 18°C) ρ 2400 kg/m to
2600 kg/m
Hardness (Knoop) HK a
0,1/20
600 - 750
Young's modulus (modulus of elasticity) E 9 × 10 Pa
...