INTERNATIONAL ISO
STANDARD 12625-6
Second edition
2016-12-01
Tissue paper and tissue products —
Part 6:
Determination of grammage
Papier tissue et produits tissue —
Partie 6: Détermination du grammage
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ISO 12625-6:2016
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89d46617a71c/iso-12625-6-2016
Reference number
ISO 12625-6:2016(E)
© ISO 2016
ISO 12625-6:2016(E)
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ISO 12625-6:2016
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89d46617a71c/iso-12625-6-2016
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ISO 12625-6:2016(E)
Contents Page
Foreword......................................................................................................................................................................................................................................... iv
1 Scope.................................................................................................................................................................................................................................. 1
2 Normative references....................................................................................................................................................................................... 1
3 Terms and definitions...................................................................................................................................................................................... 1
4 Principle......................................................................................................................................................................................................................... 1
5 Apparatus...................................................................................................................................................................................................................... 2
6 Sampling......................................................................................................................................................................................................................... 2
7 Conditioning............................................................................................................................................................................................................... 2
8 Preparation of test pieces............................................................................................................................................................................ 2
8.1 General............................................................................................................................................................................................................ 2
8.2 Cutting of the test pieces................................................................................................................................................................. 3
8.2.1 General...................................................................................................................................................................................... 3
8.2.2 Size of test pieces.............................................................................................................................................................. 3
8.2.3 Number of test pieces................................................................................................................................................... 3
8.3 Uncut finished products................................................................................................................................................................... 3
8.3.1 General...................................................................................................................................................................................... 3
8.3.2 Size of test pieces.............................................................................................................................................................. 3
8.3.3 Number of test pieces................................................................................................................................................... 3
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9 Procedure..................................................................................................................................................................................................................... 4
9.1 (standards.iteh.ai)
Determination of the mass of the test pieces................................................................................................................ 4
9.2 Determination of the area of the test pieces.................................................................................................................. 4
10 Calculation...................................................................................................................................................................................................................
ISO 12625-6:2016 4
10.1 General............................................................................................................................................................................................................ 4
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10.2 Mean and standard deviation of grammage................................................................................................................... 5
89d46617a71c/iso-12625-6-2016
11 Test report.................................................................................................................................................................................................................... 5
Annex A (informative) Precision................................................................................................................................................................................ 7
Bibliography.............................................................................................................................................................................................................................. 10
© ISO 2016 – All rights reserved iii
ISO 12625-6:2016(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely 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 ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
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constitute an endorsement.
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as well as information about ISO’s adherence to the World Trade Organization (WTO) principles in the
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Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.
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This document was prepared by the European Committee Standardization (CEN) Technical Committee
CEN/TC 172, Pulp, paper and board, in collaboration with ISO Technical Committee TC 6, Paper, board
and pulps, Subcommittee SC 2, Test methods andISO quality specifications for paper and board, in accordance
12625-6:2016
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with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
89d46617a71c/iso-12625-6-2016
This second edition cancels and replaces the first edition (ISO 12625-6:2005), which has been
technically revised with the following changes:
a) a new subclause, 8.3, has been added;
b) formulae were added to clarify Clause 10;
c) in Annex A, the precision data has been updated;
d) this document has been editorially updated.
A list of all parts in the ISO 12625 series can be found on the ISO website.
iv © ISO 2016 – All rights reserved
INTERNATIONAL STANDARD ISO 12625-6:2016(E)
Tissue paper and tissue products —
Part 6:
Determination of grammage
1 Scope
This document specifies a test method for the determination of grammage of tissue paper and tissue
products.
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 186, Paper and board — Sampling to determine average quality
ISO 187, Paper, board and pulps — Standard atmosphere for conditioning and testing and procedure for
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monitoring the atmosphere and conditioning of samples
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3 Terms and definitions
ISO 12625-6:2016
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this document, the following terms and definitions apply.
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ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
3.1
grammage
g
mass of a unit area of tissue paper or tissue product as determined by the procedure in this document
Note 1 to entry: Grammage is expressed in grams per square metre (g/m2).
4 Principle
The mass and area of a test piece or test pieces of either a tissue paper or a tissue product is measured
and the grammage is calculated as the mass per unit area of the test pieces taken. For finished paper
products, the grammage may also be calculated from the mass and area of a specified number of the
finished tissue product items. Precision data are available in Annex A.
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ISO 12625-6:2016(E)
5 Apparatus
5.1 General
The balance shall be placed on a horizontal surface free from externally induced vibrations.
5.2 Cutting device
The cutting device shall be capable of repeatedly cleanly cutting test pieces of the same nominal size,
whose area falls within ±1,0 % of a known area. This shall be checked frequently by measurement and,
provided that the above accuracy is attained, the mean area obtained in these checks shall be used for
calculating grammage.
With certain types of tissue paper and tissue product, it will be found, after carrying out this
determination of area, that test pieces cannot be cut with the accuracy just defined. In such instances,
the area of every test piece shall be determined individually.
5.3 Balance
The device to determine the balance shall have a measuring accuracy of 0,001 g.
5.4 Length measurement device
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The length measurement device shall be(standards.iteh.ai)
a ruler, an electronic digital ruler, a scanner or any other device
with a minimum measuring accuracy of 0,5 mm.
ISO 12625-6:2016
6 Sampling https://standards.iteh.ai/catalog/standards/sist/40b6e03d-4177-411b-a4c3-
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If the tests are being made to evaluate a lot, the sample shall be selected in accordance with ISO 186.
If the tests are being made on another type of sample, make sure that all specimens taken are
representative of the sample. Each test piece shall be free from perforations and faults not normally
inherent in the tissue.
7 Conditioning
Condition the samples according to ISO 187 and keep them in the standard atmosphere throughout
the test.
Conditioning shall be done prior to the preparation of test pieces.
8 Preparation of test pieces
8.1 General
Test pieces shall be free from areas containing creases, dirt or visible damage. Test pieces shall be
made of either areas cut from specimens of tissue paper or tissue products (see 8.2), or made of whole
finished products (see 8.3).
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ISO 12625-6:2016(E)
8.2 Cutting of the test pieces
8.2.1 General
In the case where test pieces are cut from specimens of tissue paper or tissue products, the test sheet or
stack of superimposed test sheets can be placed between two supporting sheets of paper, such as office
copy paper, in order to obtain test pieces with clean cut edges and dimensions of the accuracy specified.
8.2.2 Size of test pieces
Since tissue paper and tissue products vary greatly in dimensions, it is only possible to give general
guidance regarding the dimension of the test piece or test pieces.
The minimum area of an individual test piece shall be at least 100 cm2. One test piece may, if necessary,
be composed of several smaller pieces.
8.2.3 Number of test pieces
Using the cutting device (5.2), cut at least 10 test pieces. The mass of a minimum area of 1 000 cm2 shall
be determined, and convenient larger areas shall be taken in compliance with the provisions of this
document.
8.3 Uncut finished products
8.3.1 General iTeh STANDARD PREVIEW
In the case where test pieces are(standards.iteh.ai)
composed of finished tissue products, test pieces shall lie unfolded and
flat with no tension applied.
ISO 12625-6:2016
If a scanner is used https://standards.iteh.ai/catalog/standards/sist/40b6e03d-4177-411b-a4c3-
for this measurement, ensure that the scanner-cover is sufficient in size to cause the
item to lie flat. 89d46617a71c/iso-12625-6-2016
If a ruler is used, it shall be of dimensions larger than the test piece.
8.3.2 Size of test pieces
Since tissue paper and tissue products vary greatly in dimensions, it is only possible to give general
guidance regarding the dimension of the test piece or test pieces.
Using a measuring device (5.4) as described, the minimum area of an individual test piece shall be at
least 100 cm2. One test piece may, if necessary, be composed of several smaller pieces.
8.3.3 Number of test pieces
The minimum number of test pieces shall be 10. The mass of a minimum area of 1 000 cm2 shall be
determined, and convenient larger areas shall be taken in compliance with the provisions of this
document.
The 10 or more test pieces (finished product items) shall be selected from the sample in a random
manner so as to represent variation in size and mass of the finished product item present in the sample.
In any case, sequential finished product units shall never be tested, except in cases where the sample is
very limited in quantity.
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ISO 12625-6:2016(E)
9 Procedure
9.1 Determination of the mass of the test pieces
Determine the mass of each test piece on the balance (5.3) to the nearest 0,001 g.
It is recommended, especially when dealing with small test pieces, that touching the test pieces with
bare hands is avoided.
If the standard deviation is not needed, the total mass of all 10 or more test pieces may be determined
by weighing all test pieces together.
Any deviation from the procedure described above shall be explicitly mentioned in the test report.
9.2 Determination of the area of the test pieces
9.2.1 When test pieces have been cut to specified dimensions as described in 8.2, determine the area of
each individual test piece.
9.2.2 For the determination of grammage on finished paper products, the total area shall be measured
to an accuracy of better than 1 % using a measuring device (5.4) as described.
When the test pieces are measured, they shall lie unfolded and flat with no tension applied.
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If a scanner is used for this measurement, closing the scan cover is usually sufficient to cause the item
to lie flat. Likewise, placing a steel rule along the edge is usually sufficient. Where a digital ruler is
(standards.iteh.ai)
used, the finished product should be flattened using a flat piece of plastic approximately 4 mm thick, of
dimensions larger than the test piece, or a similar flattening means.
ISO 12625-6:2016
9.2.3 Any deviation from the procedure described above shall be explicitly mentioned in the test report.
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10 Calculation
10.1 General
Calculate the grammage to three significant figures for each test piece using Formula (1):
m
g= × 106 (1)
A
where
g is the grammage of the test piece, in grams per square metre;
m is the mass of the test piece, in grams;
A is the area of the test piece, in square millimetres.
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ISO 12625-6:2016(E)
10.2 Mean and standard deviation of grammage
Calculate the mean grammage of the sample and express it to three significant figures using Formula (2):
n
g=
∑ i =1 gi (2)
n
where
g is the mean grammage of the sample, in grams per square metre;
gi is the grammage of the test piece, i, in grams per square metre;
n is the number of the test pieces.
Calculate the standard deviation and express it to two significant figures using Formula (3):
n
∑ i =1 ( gi − g )
2
s= (3)
n −1
where
g is the mean grammage of the sample, in grams per square metre;
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gi is the grammage of the test piece, i, in grams per square metre;
(standards.iteh.ai)
n is the number of test pieces;
ISO 12625-6:2016
s is the sample standard deviation.
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If test pieces are weighed together, calculate the grammage using Formula (4):
n
gi =
∑ i =1 mi × 106 (4)
n× A
where
gi is the grammage of the test piece, i, in grams per square metre;
n is the number of test pieces;
m is the mass of the test piece in grams;
A is the area of each test piece, in square millimetres, where test piece areas are exactly equal
(see 5.4).
11 Test report
The test report shall include the following information:
a) a reference to this document, i.e. ISO 12625-6;
b) the date and place of testing;
c) the description and identification of the sample, such as the product category and dimensions
under test;
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