IWA 8:2009
(Main)Tableware, giftware, jewellery, luminaries — Glass clarity — Classification and test method
Tableware, giftware, jewellery, luminaries — Glass clarity — Classification and test method
IWA 8:2009 establishes requirements for the use of the glass designations “clear glass” and “ultra-clear glass” for non-coloured glass items according to their clarity and iron content. IWA 8:2009 specifies a procedure for measuring the clarity of glass items by means of a spectrophotometer. IWA 8:2009 is applicable to mineral glasses, and glass items where a part is not covered by coating or decoration, and is therefore available for sampling. IWA 8:2009 is applicable to the use of glass as tableware, giftware, jewellery and luminaries. IWA 8:2009 is not applicable to the use of glass in the context of building, containers, medicine and laboratories, and to other technical uses of glass.
Verrerie, objets de décoration, bijouterie, luminaires — Clarté du verre — Classification et méthode d'essai
General Information
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Standards Content (Sample)
International Workshop
Agreement
IWA 8
Tableware, giftware, jewellery,
luminaries — Glass clarity —
Classification and test method
* * * *
Verrerie, objets de décoration, bijouterie, luminaires — Clarté du
verre — Classification et méthode d'essai
©
ISO 2009
All rights reserved
Reference number
IWA 8:2009(E)
Corrected 2010-04-15
---------------------- Page: 1 ----------------------
IWA 8:2009(E)
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shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
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accepts no liability in this area.
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COPYRIGHT PROTECTED DOCUMENT
© ISO 2009
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2009 – All rights reserved
---------------------- Page: 2 ----------------------
Tableware, giftware, jewellery, luminaries — Glass IWA 8:2009(E)
clarity — Classification and test method
Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Specifications .1
2.1 General .1
2.2 Specifications for ultra-clear glass.1
2.3 Specifications for clear glass.2
3 Test methods .2
3.1 General .2
3.2 Apparatus.2
3.3 Sampling .3
3.4 Sample preparation.3
Annex A (normative) Determination of the lightness L* and chroma C*.5
Annex B (normative) Determination of the iron oxide content .8
Bibliography.9
© ISO 2009 – All rights reserved iii
---------------------- Page: 3 ----------------------
IWA 8:2009(E) Tableware, giftware, jewellery, luminaries — Glass
clarity — Classification and test method
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). ISO's technical work is normally carried out through ISO technical committees in which
each ISO member body has the right to be represented. International organizations, governmental and
nongovernmental, in liaison with ISO, also take part in the work.
In order to respond to urgent market requirements, ISO has also introduced the possibility of preparing
documents through a workshop mechanism, external to its normal committee processes. These documents
are published by ISO as International Workshop Agreements. Proposals to hold such workshops may come
from any source and are subject to approval by the ISO Technical Management Board which also designates
an ISO member body to assist the proposer in the organization of the workshop. International Workshop
Agreements are approved by consensus amongst the individual participants in such workshops. Although it is
permissible that competing International Workshop Agreements exist on the same subject, an International
Workshop Agreement shall not conflict with an existing ISO or IEC standard.
An International Workshop Agreement is reviewed after three years, under the responsibility of the member
body designated by the Technical Management Board, in order to decide whether it will be confirmed for a
further three years, transferred to an ISO technical body for revision, or withdrawn. If the International
Workshop Agreement is confirmed, it is reviewed again after a further three years, at which time it must be
either revised by the relevant ISO technical body or withdrawn.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Workshop Agreement IWA 8 was drafted at a workshop held in Paris, France, in October 2009.
The workshop, which was proposed by the Institut du Verre and mandated by the International Crystal
Federation (ICF) and its European arm European Domestic Glass (EDG), was organized jointly by the Institut
du Verre and the Association Française de Normalisation (AFNOR).
This corrected version of IWA 8:2009 incorporates the following correction:
⎯ an error in Equation (A.1) has been corrected.
iv © ISO 2009 – All rights reserved
---------------------- Page: 4 ----------------------
Tableware, giftware, jewellery, luminaries — Glass IWA 8:2009(E)
clarity — Classification and test method
Introduction
This International Workshop Agreement is intended to provide a generic definition and classification of glass
clarity to permit a global understanding of consumer quality requirements, with a corresponding method to
measure glass clarity.
For glass clarity, spectrophotometric measurement is performed in accordance with CIE 15:2004 with a
predefined choice of illuminate and observer. Measurement on the sample at two different thicknesses permits
calculation of internal transmission for a defined intermediate thickness and indicates glass clarity irrespective
of the refractive index value. The same methodology applies for all mineral glasses.
This method has been verified in accordance with visual inspection with a light cabinet. In addition, preliminary
collaborative studies have confirmed the results of these measurements as being coherent with both
consumer perception and quality recognition.
As it is well known that iron is by far the main contaminant of glass raw materials affecting the transparency
and colorimetric purity of the glass, the iron content has been considered as an additional criterion.
© ISO 2009 – All rights reserved v
---------------------- Page: 5 ----------------------
Tableware, giftware, jewellery, luminaries — Glass IWA 8:2009(E)
clarity — Classification and test method
Tableware, giftware, jewellery, luminaries — Glass clarity —
Classification and test method
1 Scope
This International Workshop Agreement establishes requirements for the use of the glass designations “clear
glass” and “ultra-clear glass” for non-coloured glass items according to their clarity and iron content. This
International Workshop Agreement specifies a procedure for measuring the clarity of glass items by means of
a spectrophotometer.
This International Workshop Agreement is applicable to
⎯ mineral glasses, and
⎯ glass items where a part is not covered by coating or decoration, and is therefore available for sampling.
This International Workshop Agreement is applicable to the use of glass as tableware, giftware, jewellery and
luminaries.
This International Workshop Agreement is not applicable to the use of glass in the context of building,
containers, medicine and laboratories, and to other technical uses of glass.
2 Specifications
2.1 General
The classification of the samples of glass in terms of clarity is based on three criteria:
⎯ lightness, L*;
⎯ chroma, C*;
⎯ iron content of the material.
The iron content is a main contaminant influencing the transparency and colour of the glass; the value is
expressed in iron oxide (Fe O ) in mg/kg.
2 3
NOTE The best classification of clarity is obtained for the maximum value of lightness L* at 100 and the minimum
value of chroma C* at zero.
2.2 Specifications for ultra-clear glass
Ultra-clear glass shall have:
⎯ lightness L* W 98,8;
⎯ chroma C* u 0,5;
© ISO 2009 – All rights reserved 1
---------------------- Page: 6 ----------------------
IWA 8:2009(E) Tableware, giftware, jewellery, luminaries — Glass
clarity — Classification and test method
⎯ iron oxide content u 140 mg/kg.
If one or more of these criteria are not reached, the glass cannot be classified as ultra-clear glass.
2.3 Specifications for clear glass
Clear glass shall have:
⎯ lightness L* W 98,0;
⎯ chroma C* u 0,5;
⎯ iron oxide content u 200 mg/kg.
If one or more of these criteria are not reached, the glass cannot be classified as clear glass.
3 Test methods
3.1 General
The sample shall be prepared in accordance with 3.3 and 3.4. The same sample shall be used to characterize
the three criteria, in accordance with the following two determination methods:
⎯ Annex A shall apply for the determination of lightness L* and chroma C*;
⎯ Annex B shall apply for the determination of the iron oxide content.
3.2 Apparatus
3.2.1 Double-beam spectrophotometer, preferably with integrating sphere.
3.2.2 X-ray fluorescence spectrometer, with wavelength dispersion.
3.2.3 Non-metallic hammer.
3.2.4 Non-metallic plate.
3.2.5 Platinum crucible, compatible with the final dimensions of the sample(s).
3.2.6 Electric oven, capable of maintaining a temperature of 1 300 °C for a duration of 16 h.
3.2.7 Polishing device.
3.2.8 Manual grinding device, with silicium carbide (SiC) abrasive.
3.2.9 Automatic grinding machine.
3.2.10 Automatic polishing device.
2 © ISO 2009 – All rights reserved
---------------------- Page: 7 ----------------------
Tableware, giftware, jewellery, luminaries — Glass IWA 8:2009(E)
clarity — Classification and test method
3.3 Sampling
3.3.1 General
The sampling is carried out to prepare two pieces of glass:
⎯ the first with a minimum dimension of 30 mm for one face;
⎯ the second with a minimum dimension of 10 mm for one face.
The two other dimensions shall be greater than the slide dimensions of the spectrophotometer (3.2.1) for the
two pieces.
3.3.2 Cutting
Cut a glass block from the glass item (e.g. tumblers with a thick bottom).
For glass items covered
...
International Workshop
Agreement
IWA 8
Tableware, giftware, jewellery,
luminaries — Glass clarity —
Classification and test method
* * * *
Verrerie, objets de décoration, bijouterie, luminaires — Clarté du
verre — Classification et méthode d'essai
Reference number ©
ISO 2009
IWA 8:2009(E)
All rights reserved
---------------------- Page: 1 ----------------------
IWA 8:2009(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
COPYRIGHT PROTECTED DOCUMENT
© ISO 2009
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2009 – All rights reserved
---------------------- Page: 2 ----------------------
Tableware, giftware, jewellery, luminaries — Glass IWA 8:2009(E)
clarity — Classification and test method
Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Specifications .1
2.1 General .1
2.2 Specifications for ultra-clear glass.1
2.3 Specifications for clear glass.2
3 Test methods .2
3.1 General .2
3.2 Apparatus.2
3.3 Sampling .3
3.4 Sample preparation.3
Annex A (normative) Determination of the lightness L* and chroma C*.5
Annex B (normative) Determination of the iron oxide content .8
Bibliography.9
© ISO 2009 – All rights reserved iii
---------------------- Page: 3 ----------------------
IWA 8:2009(E) Tableware, giftware, jewellery, luminaries — Glass
clarity — Classification and test method
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). ISO's technical work is normally carried out through ISO technical committees in which
each ISO member body has the right to be represented. International organizations, governmental and
nongovernmental, in liaison with ISO, also take part in the work.
In order to respond to urgent market requirements, ISO has also introduced the possibility of preparing
documents through a workshop mechanism, external to its normal committee processes. These documents
are published by ISO as International Workshop Agreements. Proposals to hold such workshops may come
from any source and are subject to approval by the ISO Technical Management Board which also designates
an ISO member body to assist the proposer in the organization of the workshop. International Workshop
Agreements are approved by consensus amongst the individual participants in such workshops. Although it is
permissible that competing International Workshop Agreements exist on the same subject, an International
Workshop Agreement shall not conflict with an existing ISO or IEC standard.
An International Workshop Agreement is reviewed after three years, under the responsibility of the member
body designated by the Technical Management Board, in order to decide whether it will be confirmed for a
further three years, transferred to an ISO technical body for revision, or withdrawn. If the International
Workshop Agreement is confirmed, it is reviewed again after a further three years, at which time it must be
either revised by the relevant ISO technical body or withdrawn.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Workshop Agreement IWA 8 was drafted at a workshop held in Paris, France, in October 2009.
The workshop, which was proposed by the Institut du Verre and mandated by the International Crystal
Federation (ICF) and its European arm European Domestic Glass (EDG), was organized jointly by the Institut
du Verre and the Association Française de Normalisation (AFNOR).
iv © ISO 2009 – All rights reserved
---------------------- Page: 4 ----------------------
Tableware, giftware, jewellery, luminaries — Glass IWA 8:2009(E)
clarity — Classification and test method
Introduction
This International Workshop Agreement is intended to provide a generic definition and classification of glass
clarity to permit a global understanding of consumer quality requirements, with a corresponding method to
measure glass clarity.
For glass clarity, spectrophotometric measurement is performed in accordance with CIE 15:2004 with a
predefined choice of illuminate and observer. Measurement on the sample at two different thicknesses permits
calculation of internal transmission for a defined intermediate thickness and indicates glass clarity irrespective
of the refractive index value. The same methodology applies for all mineral glasses.
This method has been verified in accordance with visual inspection with a light cabinet. In addition, preliminary
collaborative studies have confirmed the results of these measurements as being coherent with both
consumer perception and quality recognition.
As it is well known that iron is by far the main contaminant of glass raw materials affecting the transparency
and colorimetric purity of the glass, the iron content has been considered as an additional criterion.
© ISO 2009 – All rights reserved v
---------------------- Page: 5 ----------------------
Tableware, giftware, jewellery, luminaries — Glass IWA 8:2009(E)
clarity — Classification and test method
Tableware, giftware, jewellery, luminaries — Glass clarity —
Classification and test method
1 Scope
This International Workshop Agreement establishes requirements for the use of the glass designations “clear
glass” and “ultra-clear glass” for non-coloured glass items according to their clarity and iron content. This
International Workshop Agreement specifies a procedure for measuring the clarity of glass items by means of
a spectrophotometer.
This International Workshop Agreement is applicable to
⎯ mineral glasses, and
⎯ glass items where a part is not covered by coating or decoration, and is therefore available for sampling.
This International Workshop Agreement is applicable to the use of glass as tableware, giftware, jewellery and
luminaries.
This International Workshop Agreement is not applicable to the use of glass in the context of building,
containers, medicine and laboratories, and to other technical uses of glass.
2 Specifications
2.1 General
The classification of the samples of glass in terms of clarity is based on three criteria:
⎯ lightness, L*;
⎯ chroma, C*;
⎯ iron content of the material.
The iron content is a main contaminant influencing the transparency and colour of the glass; the value is
expressed in iron oxide (Fe O ) in mg/kg.
2 3
NOTE The best classification of clarity is obtained for the maximum value of lightness L* at 100 and the minimum
value of chroma C* at zero.
2.2 Specifications for ultra-clear glass
Ultra-clear glass shall have:
⎯ lightness L* W 98,8;
⎯ chroma C* u 0,5;
© ISO 2009 – All rights reserved 1
---------------------- Page: 6 ----------------------
IWA 8:2009(E) Tableware, giftware, jewellery, luminaries — Glass
clarity — Classification and test method
⎯ iron oxide content u 140 mg/kg.
If one or more of these criteria are not reached, the glass cannot be classified as ultra-clear glass.
2.3 Specifications for clear glass
Clear glass shall have:
⎯ lightness L* W 98,0;
⎯ chroma C* u 0,5;
⎯ iron oxide content u 200 mg/kg.
If one or more of these criteria are not reached, the glass cannot be classified as clear glass.
3 Test methods
3.1 General
The sample shall be prepared in accordance with 3.3 and 3.4. The same sample shall be used to characterize
the three criteria, in accordance with the following two determination methods:
⎯ Annex A shall apply for the determination of lightness L* and chroma C*;
⎯ Annex B shall apply for the determination of the iron oxide content.
3.2 Apparatus
3.2.1 Double-beam spectrophotometer, preferably with integrating sphere.
3.2.2 X-ray fluorescence spectrometer, with wavelength dispersion.
3.2.3 Non-metallic hammer.
3.2.4 Non-metallic plate.
3.2.5 Platinum crucible, compatible with the final dimensions of the sample(s).
3.2.6 Electric oven, capable of maintaining a temperature of 1 300 °C for a duration of 16 h.
3.2.7 Polishing device.
3.2.8 Manual grinding device, with silicium carbide (SiC) abrasive.
3.2.9 Automatic grinding machine.
3.2.10 Automatic polishing device.
2 © ISO 2009 – All rights reserved
---------------------- Page: 7 ----------------------
Tableware, giftware, jewellery, luminaries — Glass IWA 8:2009(E)
clarity — Classification and test method
3.3 Sampling
3.3.1 General
The sampling is carried out to prepare two pieces of glass:
⎯ the first with a minimum dimension of 30 mm for one face;
⎯ the second with a minimum dimension of 10 mm for one face.
The two other dimensions shall be greater than the slide dimensions of the spectrophotometer (3.2.1) for the
two pieces.
3.3.2 Cutting
Cut a glass block from the glass item (e.g. tumblers with a thick bottom).
For glass items covered with coating or decoration, or for glass items of which the minimum dime
...
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