BS EN 12705:2011

BSI Standards Publication

Adhesives for leather and

footwear materials —
Determination of colour
change of white or bright
coloured leather surfaces
by migration
BS EN 12705:2011 BRITISH STANDARD

National foreword
This British Standard is the UK implementation of EN 12705:2011.
It supersedes BS EN 12705:2000, which is withdrawn.
The UK participation in its preparation was entrusted to
Technical Committee PRI/52, Adhesives.
A list of organizations represented on this committee can be
obtained on request to its secretary.
This publication does not purport to include all the necessary
provisions of a contract. Users are responsible for its correct
application.
© BSI 2011
ISBN 978 0 580 72241 7
ICS 83.180
Compliance with a British Standard cannot confer immunity
from legal obligations.
This British Standard was published under the authority of the
Standards Policy and Strategy Committee on 30 June 2011.
Amendments issued since publication
Date Text affected
 BS EN 12705:2011

EUROPEAN STANDARD EN 12705

NORME EUROPÉENNE
EUROPÄISCHE NORM May 2011

ICS 83.180 Supersedes EN 12705:1999

English Version

Adhesives for leather and footwear materials - Determination of

colour change of white or bright coloured leather surfaces by
migration

Adhésifs pour le cuir et les matériaux de chaussures - Klebstoffe für Leder und Schuhwerkstoffe - Bestimmung
Détermination du changement de couleur par migration des der Farbänderung weißer oder hellfarbiger
surfaces de cuir blanc ou de couleurs claires Lederoberflächen durch Migration

This European Standard was approved by CEN on 24 March 2011.

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. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.

This European Standard exists 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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION

COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2011 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 12705:2011: E
worldwide for CEN national Members.
BS EN 12705:2011
EN 12705:2011 (E)

Contents Page

Foreword ..............................................................................................................................................................3
1 Scope ......................................................................................................................................................4
2 Normative references ............................................................................................................................4
3 Terms and definitions ...........................................................................................................................4
4 Principle ..................................................................................................................................................4
5 Apparatus and materials .......................................................................................................................5
6 Leather ....................................................................................................................................................5
7 Adhesive .................................................................................................................................................5
8 Preparation of test specimens and reference leather pieces ...........................................................5
9 Procedure ...............................................................................................................................................6
9.1 Colour measurement of test specimens and reference leather pieces ...........................................6
9.2 Storage/exposure of test specimens and reference leather pieces .................................................6
9.2.1 General ....................................................................................................................................................6
9.2.2 Storage 7 days at (60 ± 2) °C in the dark between glass plates ........................................................6
9.2.3 Exposure 7 days to light .......................................................................................................................6
9.2.4 Other storage conditions ......................................................................................................................7
10 Expression of results ............................................................................................................................7
11 Test report ..............................................................................................................................................7

2
 BS EN 12705:2011
EN 12705:2011 (E)

Foreword
This document (EN 12705:2011) has been prepared by Technical Committee CEN/TC 193 “Adhesives”, the
secretariat of which is held by AENOR.

This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by November 2011, and conflicting national standards shall be withdrawn
at the latest by November 2011.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.

This document supersedes EN 12705:1999.

SAFETY STATEMENT— Persons using this document should be familiar with the normal laboratory practice,
if applicable. This document does not purport to address all of the safety problems, if any, associated with its
use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure
compliance with any regulatory conditions.

ENVIRONMENTAL STATEMENT — It is understood that some of the material permitted in this standard may
have negative environmental impact. As technological advantages lead to acceptable alternatives for these
materials, they will be eliminated from this standard to the extent possible.

According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.

3
BS EN 12705:2011
EN 12705:2011 (E)

1 Scope
This European Standard specifies a method to determine the colour change of white or bright coloured leather
surfaces caused by adhesives and/or their basic constituents migrating from the reverse sides to their upper
surfaces.

This change of colour may be caused either by the adhesive directly or by adhesive coatings on materials
used in footwear manufacture, e.g. adhesive coated linings for ironing, toe-puffs, reinforcing tapes or bonded
materials.

2 Normative references
The following referenced documents are indispensable for the application 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.

EN 923:2005+A1:2008, Adhesives — Terms and definitions

EN 1067, Adhesives — Examination and preparation of samples for testing

EN 1244, Adhesives — Determination of the colour and/or colour changes of adhesive coats under the
influence of light

EN ISO 15605, Adhesives — Sampling (ISO 15605:2000)

ISO 2602, Statistical interpretation of test results — Estimation of the mean — Confidence interval

CIE 15:2004, Colorimetry

3 Terms and definitions

For the purposes of this document, the terms and definitions given in EN 923:2005+A1:2008 and the following
apply.

3.1
leather
tanned animal skin, usually free of hair

3.2
colour
sensation perceived by the human eye

4 Principle
The bonding adhesive is coated on the reverse side of the leather under test and allowed to dry, to cool or to
set for specified period of time.

The colour of the upper side of the leather is measured and the test specimen is stored under specified
conditions. The colour of the test specimen is measured after storage.

4
 BS EN 12705:2011
EN 12705:2011 (E)

5 Apparatus and materials

Ordinary laboratory apparatus and in particular:

5.1 Cutting knife, for cutting leather.

5.2 Coating device, to spread the adhesive to be used on the pieces of leather to be tested, capable of
producing a flat surface coating with a measurable uniform thickness after drying, cooling or setting.

5.3 Analytical balance, with scale division of 0,001 g for weighing test pieces.

5.4 Glass plates, even and smooth at least 70 mm x 70 mm with a mass about 40 g for covering test
specimens and reference leather pieces.

5.5 Release agent, non-staining, to prevent sticking of the test specimens to the glass plates.

5.6 Weights, with a mass (1 000 ± 10) g for loading test specimens.

5.7 Colorimeter, for measuring the colour of test specimens and reference leather pieces capable of
* * *
converting the readings to the CIE colour scale values L , a and b and of calculating the CIELAB colour
* * * *
differences ∆L , ∆a , ∆b and ∆E ab automatically in accordance with CIE 15:2004.

5.8 Oven, for storing loaded test specimens and reference leather pieces in the dark at a temperature of
(60 ± 2) °C.

5.9 Light exposure apparatus, in accordance with EN 1244 containing a xenon arc lamp, a light filter, a
heat filter, a temperature sensor and an irradiation-measuring device.

6 Leather
The leather to be tested shall have a uniform surface of the upper side and an even, uniform reverse side free
from any contamination (e.g. adhesives, dust or release agents).

Identify the leather as fully as possible. Record type and name and/or designation of the leather, supplier, date
of supply, colour, thickness and, if known, type of tanning, and the composition of a surface coat, if any.

7 Adhesive
Identify the adhesive used by name and/or designation, manufacturer, date of manufacture/supply and/or lot
number, expiry date, main polymer, colour and viscosity in the test report. For two-part adhesives identify also
the nature of the crosslinking agent and mixing ratio of the components.

8 Preparation of test specimens and reference leather pieces

Cut, using a cutting knife (5.1), from the leather to be tested, two rectangular pieces
(200 ± 5) mm x (70 ± 5) mm.

Take a sample in accordance with EN ISO 15605 of the adhesive to be used and examine and prepare it in
accordance with EN 1067.

Apply the adhesive within the limits given by the adhesive manufacturer on the reverse side of one of the
leather pieces cut as above indicated and spread the adhesive by a coating device (5.2) so that it covers the
full area. The dry coat shall have an equal thickness, a uniform surface structure and shall not contain any
bubbles.

5
BS EN 12705:2011
EN 12705:2011 (E)

Allow the adhesive coat to dry, cool or set for the period of time specified by the adhesive manufacturer. If not
specified use (30 ± 5) min at a controlled temperature of (23 ± 5) °C and a relative humidity of less than 70 %.

The adhesive used can be applied in accordance with the instructions of its manufacture by several coats
(always after drying of the preceding coat) on the leather piece. Record the number of adhesive coats applied
and the drying times in the test report.

Cut from the coated leather piece at least three pieces (test specimens) (50 ± 2) mm x (50 ± 2) mm and from
the uncoated leather pieces, the same number of pieces (reference leather pieces) of the same dimensions.

Determine the mass of dried adhesive applied by weighing the test pieces, with and without adhesive, using
the analytical balance (5.3) and record it.

9 Procedure

9.1 Colour measurement of test specimens and reference leather pieces

Standardise the colorimeter (5.7) to a white standard (standard illuminant D 65, standard observer 10°,
geometry of measurement d/8°), before any measurement.
* * *
Determine all CIE L , a and b values of test specimens and reference leather pieces by the colorimeter in
accordance with CIE 15:2004. Note all values measured in the test report.

9.2 Storage/exposure of test specimens and reference leather pieces

9.2.1 General

Depending on the type of leather to be tested and the adhesive used in practice colour changes of white or
bright coloured leather surfaces caused by migration often appear accelerated under the influence of heat
and/or light.

Taking into account this experience store the 3 test specimens prepared according to Clause 8 and the same
number of reference pieces.

9.2.2 Storage 7 days at (60 ± 2) °C in the dark between glass plates

Measure the colour values of the test specimens and of the reference leather pieces before storage as
specified in 9.1 and note the colour values in the test report.

Place the test specimens and the reference leather pieces between two-glass plates (5.4). If required, use a
light coat of a non-stainig release agent (5.5). Load these assemblies with a 1 000 g weight (5.6) and store
them with the uncoated leather upper sides uppermost in an oven (5.8) controlled at (60 ± 2) °C, during 7 days.

Each day take the assemblies from the oven, remove the glass plates from the test specimens and the
reference leather pieces, measure their colour values as specified in 9.1 and note them in the test report.
Replace the glass plates and store them again in the oven.

Repeat this procedure until a colour change of ∆Eab* 0,5 or more appears or at least up to 7 days.

9.2.3 Exposure 7 days to light

Measure the colour values of the test specimens and of the reference leather pieces as specified in 9.1 and
note them in the test report.

Mount the test specimens and the reference leather pieces in a holder of the exposure apparatus (5.9) and
proceed in accordance with EN 1244.

6
 BS EN 12705:2011
EN 12705:2011 (E)

Measure at daily intervals the colour values of the test specimens and of the reference leather pieces as
specified in 9.1 and note them in the test report.

Continue with the exposure until a discoloration of ∆Eab* 0,5 or more appears or at least up to 7 days.

9.2.4 Other storage conditions

Others requirements, combined or sequential storage conditions (e.g. light exposure followed by storage at
elevated temperature), may be chosen. Identify such conditions and record the results obtained in the test
report.

10 Expression of results
* * *
Express the results by indicating the CIE colour scale values L , a and b of each test specimen and reference
* * *
leather piece both unstored/unexposed and stored/exposed and the CIE colour differences ∆L , ∆a , ∆b and
*
∆E ab of these values calculated by a colorimeter (5.7) in accordance with CIE 15:2004. All values shall
represent the arithmetic mean in accordance with ISO 2602 of at least 5 readings.

Colour differences of ∆Eab* 0,5 or less have to be ignored as they are insignificant.

11 Test report
The test report shall include:

a) a reference to this European Standard;

b) a detailed description of the leather to be tested according to Clause 6 and of any surface treatment of
the leather after the test;

c) complete identification of the adhesive used according to Clause 7;

d) mass of final total adhesive coat applied in grams, number of the adhesive coats, drying time(s), and, if
used, name and/or designation of a release agent;

e) description of the colorimeter used (type, manufacturer, calibration etc.), mode and conditions of the
colour measurement (type of illumination and observer, geometry of measurement);

f) if test specimens are exposed to light description of the light exposure apparatus (type, manufacturer,
lamp, filter system) and of the conditions of the exposure (intensity of irradiation, surface temperature of
the specimens), rotation rate of the carousel used in the test chamber;

g) test results according to Clause 10;

h) any modification to the procedure described, and any incident which may have affected the results;

i) date of the test.

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