ISO/FDIS 23999

ISO/TC 219
Secretariat: NBN
Date: 2025-07-0308-12
Resilient floor coverings — Determination of dimensional stability
and curling (vertical deformation) after exposure to heat
Revêtements de sol résilients — Détermination de la stabilité dimensionnelle et de l'incurvationl’incurvation
(déformation verticale) après exposition à la chaleur
FDIS stage
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Published in Switzerland
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Contents
Foreword . iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
4.1 General . 2
4.2 Dimensional stability . 2
4.3 Curling (vertical deformation) . 2
5 Apparatus . 2
5.1 Oven . 2
5.2 Support plates . 3
6 Measuring devices . 3
6.1 Measurement devices for determination of curling (vertical deformation) . 3
6.2 Measurement devices for determination of linear dimension changes . 3
7 Test specimens . 9
7.1 Specimen preparation from sheet or roll material . 9
7.2 Specimen preparation from tiles and planks . 11
8 Conditioning . 12
9 Test procedure . 12
9.1 Initial measurement . 12
9.2 Heat exposure . 14
9.3 Reconditioning . 14
9.4 Final measurement . 15
10 Calculation and expression of results . 15
10.1 Curling (vertical deformation) . 15
10.2 Dimensional change . 16
11 Test report . 16
Annex A (informative) Measurement of dimensional change due to heat . 18
Annex B (informative) Calculation and expression of results . 19

Contents
iii
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 document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see http://www.iso.org/directives).
Field Code Changed
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s)
which may be required to implement this document. However, implementers are cautioned that this may not
represent the latest information, which may be obtained from the patent database available at
http://www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
http://www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 219, Floor coverings, in collaboration with the
European Committee for Standardization (CEN) Technical Committee CEN/TC 134 Resilient, textile, laminate
and modular mechanical locked floor coverings, in accordance with the Agreement on technical cooperation
between ISO and CEN (Vienna Agreement).
This fourth edition cancels and replaces the third edition (ISO 23999:2021), which has been technically
revised.
The main changes are as follows:
— — revision of terms and definitions;
— — clarification on the deviation between devices used for either sheet or roll, or both, materials and
rectangular shaped elements (squared tiles or long panels);
— — inclusion of an explanation on the use of the so called “block and dial gauge apparatus” and minor
changes to the figures and a new figure was added;
— — inclusion of description of the preparation distinguishing sheet, roll materials and rectangular shaped
elements (squared tiles or long panels);
— — detailed calculation and expression of results can be found in new Annex BAnnex B.
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 http://www.iso.org/members.html.
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DRAFT International Standard ISO/FDIS 23999:2025(en)

Resilient floor coverings — Determination of dimensional stability
and curling (vertical deformation) after exposure to heat
1 Scope
This document specifies methods for determining dimensional stability and curling (vertical deformation) of
resilient floor coverings in all forms (e.g. of sheets, tiles, panels, planks or in rolls) after exposure to either heat
or after reconditioning, or both.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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
Field Code Changed
— — IEC Electropedia: available at https://www.electropedia.org/
Field Code Changed
3.1 3.1
dimensional stability
ability of a resilient floor covering to retain its original linear dimensions after exposure to heat, determined
by measuring the linear dimensional change in machine direction or across machine direction
Note 1 to entry: Retaining original linear dimensions includes no elongation or shrinking.
3.2 3.2
curling
vertical deformation
vertically concave (+) or convex (-) deformation from the horizontal
3.3 3.3
concave deformation
type of curling (vertical deformation) appearing as uplifted top surface at the outer edge of the specimen;
given as positive value (+)
3.4 3.4
convex deformation
type of curling (vertical deformation) appearing as uplifted, domed top surface in the centre of the specimen;
given as negative value (-)
3.5 3.5
machine direction
MD
direction parallel to the length side of a floor covering manufactured in a continuous process
Note 1 to entry: For rectangular or squared cut specimens (e.g. tiles and planks) where the machine direction cannot be
determined, the direction of MD can be arbitrarily assigned for the test to enable differentiation from across machine
direction (AMD).
3.6 3.6
across machine direction
AMD
direction across to the length side of a floor covering manufactured in a continuous process
Note 1 to entry: For rectangular or squared cut specimens (e.g. tiles and planks) where the across machine direction
cannot be determined, the AMD can be arbitrarily assigned for the test to enable differentiation from machine direction
(MD).
4 Principle
4.1 General
Three test specimens are initially measured and then placed in an oven at an elevated temperature which can
cause dimensional changes and curl. After a specific period in the oven and subsequent time of reconditioning,
dimensional stability and the stability against vertical deformation (curling) are measured again on the same
test specimens.
4.2 Dimensional stability
The relative change in linear distance between the same marks or same specific locations of the top surface
layer of a test specimen, measured after exposure to a heat treatment and reconditioning. Depending on the
size of the specimen and the structure of the surface, different measuring devices can therefore be appropriate.
As a special interest case, the change of linear dimensions can be determined on hot test specimens, meaning
before reconditioning. As this does not affect the measurement of dimensional stability and curling, it may be
determined as an intermediate result on the same test specimens (see Annex AAnnex A).).
4.3 Curling (vertical deformation)
Curling is measured at the highest peaks of the test specimens, possibly occurring after the specified heat
treatment in an oven at an elevated temperature and reconditioning in a normal conditioned climate.
An initial vertical deformation of the test specimen (before the exposure to heat) may be measured (see
Figure 7Figure 7).).
5 Apparatus
5.1 Oven
The oven shall be thermostatically controlled and ventilated, capable of being maintained at a uniform
temperature with maximum deviations of ±2 °C.
The oven shall allow for specimens to be placed inside in a way that ensures that radiation from the heating
elements does not directly reach the test specimens or support plates (see 5.25.2).). Therefore, the distance
between the support plates and the vertical walls of the oven shall be more than 50 mm and the vertical
distance between the support plates and between the plates and the oven ceiling and base shall be more than
100 mm.
5.2 Support plates
The support plates on which the specimens will be placed for the test shall be of metal, e.g. aluminium or
stainless steel, and 2,0 ± 0,5 mm in thickness. The overall length and width of the support plates shall be of
dimensions larger than the test specimen. Ensure that the support plates are kept smooth and polished so that
surface friction does not interfere with free shrinkage or growth of the test specimens. The plates shall be flat
and free of convex or concave distortion and fully support the specimen (e.g. a wire rack support plate is not
acceptable.).
6 Measuring devices
6.1 Measurement devices for determination of curling (vertical deformation)
The measuring equipment can be any appropriate apparatus or device capable of measuring sma
...