EN 14257:2019
(Main)Adhesives - Wood adhesives - Determination of tensile strength of lap joints at elevated temperature (WATT '91)
Adhesives - Wood adhesives - Determination of tensile strength of lap joints at elevated temperature (WATT '91)
This document specifies a method for testing the strength of wood adhesives at 80 °C.
NOTE The procedure described is based on a test developed in Germany known originally as the WATT '91 test. It uses the test piece described in EN 205.
Klebstoffe - Holzklebstoffe - Bestimmung der Klebfestigkeit von Längsklebungen im Zugversuch in der Wärme (WATT'91)
Dieses Dokument legt ein Verfahren zur Prüfung der Festigkeit von Holzklebstoffen bei 80 °C fest.
ANMERKUNG Das beschriebene Verfahren geht auf eine in Deutschland entwickelte Prüfung zurück, die als WATT'91 bekannt wurde. Es werden die in EN 205 beschriebenen Prüfkörper verwendet.
Adhésifs - Adhésifs pour bois - Détermination de la résistance en traction à température élevée des joints à recouvrement (essai WATT '91)
Le présent document spécifie une méthode d’essai de la résistance à 80 °C des adhésifs pour bois.
NOTE La méthode décrite reprend un essai mis au point en Allemagne, initialement connu sous le nom d’essai WATT ’91. Elle utilise l’éprouvette correspondant à la description de l’EN 205.
Lepila - Lepila za les - Ugotavljanje natezne trdnosti spojev s preklopom pri povišani temperaturi (WATT ’91)
Ta dokument določa metodo preskušanja trdnosti lepil za les pri temperaturi 80 °C.
OPOMBA: Opisani postopek temelji na preskusu, ki je bil razvit v Nemčiji in je bil prvotno znan kot preskus WATT '91. V preskusu se uporablja preskušanec, opisan v standardu EN 205.
General Information
- Status
- Published
- Publication Date
- 24-Sep-2019
- Withdrawal Date
- 30-Mar-2020
- Technical Committee
- CEN/TC 193 - Adhesives
- Drafting Committee
- CEN/TC 193/SC 1/WG 12 - Adhesives for non-loadbearing timber structures
- Current Stage
- 9093 - Decision to confirm - Review Enquiry
- Start Date
- 12-Mar-2025
- Completion Date
- 14-Apr-2025
Relations
- Effective Date
- 08-Jun-2022
Overview
EN 14257:2019 - "Adhesives - Wood adhesives - Determination of tensile strength of lap joints at elevated temperature (WATT '91)" is a CEN standard that specifies a laboratory method to measure the tensile (hot) strength of bonded wood lap joints at 80 °C. The procedure is based on the German WATT '91 test and uses the test-piece geometry described in EN 205. EN 14257:2019 replaces EN 14257:2006 and was approved by CEN in 2019.
Key Topics and Requirements
- Scope: Test strength of wood adhesives at (80 ± 2) °C using thin (0.1 mm) glue lines and symmetrical bonded lap joints.
- Number of specimens: Prepare and test 20 bonded test pieces following EN 205.
- Conditioning: After bonding and pressing, condition assemblies for a minimum of 7 days in a standard atmosphere: either 20 ± 2 °C / 65 ± 5 % RH or 23 ± 2 °C / 50 ± 5 % RH.
- Heating and test timing: Place each test piece in a preheated fan oven at 80 ± 2 °C for 60 ± 2 minutes. The time between removal from the oven and the start of the tensile test must be (9 ± 1) s.
- Apparatus: Use a tensile testing machine conforming to ISO 5893 with self-aligning jaws and a fan-assisted oven for temperature control.
- Rate of traverse: Approximately 50 mm/min for thermoplastic adhesives; 6–12 mm/min for thermosetting adhesives.
- Result calculation: Hot strength τ is calculated as τ = F_max / (l · b) in N/mm², where F_max is the maximum force and l and b are bond length and width (see EN 205).
- Test report: Must record adhesive identification, bonding details (wood species, moisture, glue spread, pressing parameters), conditioning, traverse rate, and detailed results for each specimen (individual τ values, mean, standard deviation, coefficient of variation, and percentage of wood failure).
Applications and Who Uses It
- Adhesive manufacturers - for product performance data and quality control at elevated temperatures.
- Independent testing laboratories - to provide standardized tensile strength test reports for certification and R&D.
- Wood product manufacturers (furniture, joinery, laminated wood) - to select adhesives that retain strength under heat.
- Standards and certification bodies - for compliance assessments and comparability between adhesives.
- R&D teams - to compare thermoplastic vs thermosetting adhesive behaviour at elevated temperature.
EN 14257:2019 is essential when assessing how adhesives perform under thermal stress and for ensuring consistent, comparable tensile-strength data for wood bonding at elevated temperature.
Related Standards
- EN 205 - Test piece geometry and tensile shear strength of lap joints (used by EN 14257)
- EN 923 - Adhesives - Terms and definitions
- ISO 5893 - Specification for tensile testing machines
Frequently Asked Questions
EN 14257:2019 is a standard published by the European Committee for Standardization (CEN). Its full title is "Adhesives - Wood adhesives - Determination of tensile strength of lap joints at elevated temperature (WATT '91)". This standard covers: This document specifies a method for testing the strength of wood adhesives at 80 °C. NOTE The procedure described is based on a test developed in Germany known originally as the WATT '91 test. It uses the test piece described in EN 205.
This document specifies a method for testing the strength of wood adhesives at 80 °C. NOTE The procedure described is based on a test developed in Germany known originally as the WATT '91 test. It uses the test piece described in EN 205.
EN 14257:2019 is classified under the following ICS (International Classification for Standards) categories: 83.180 - Adhesives. The ICS classification helps identify the subject area and facilitates finding related standards.
EN 14257:2019 has the following relationships with other standards: It is inter standard links to EN 14257:2006. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
EN 14257:2019 is associated with the following European legislation: EU Directives/Regulations: 305/2011. When a standard is cited in the Official Journal of the European Union, products manufactured in conformity with it benefit from a presumption of conformity with the essential requirements of the corresponding EU directive or regulation.
EN 14257:2019 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
SLOVENSKI STANDARD
01-december-2019
Nadomešča:
SIST EN 14257:2006
Lepila - Lepila za les - Ugotavljanje natezne trdnosti spojev s preklopom pri
povišani temperaturi (WATT ’91)
Adhesives - Wood adhesives - Determination of tensile strength of lap joints at elevated
temperature (WATT '91)
Klebstoffe - Holzklebstoffe - Bestimmung der Klebfestigkeit von Längsklebungen im
Zugversuch in der Wärme (WATT'91)
Adhésifs - Adhésifs pour bois - Détermination de la résistance en traction à température
élevée des joints à recouvrement (essai WATT '91)
Ta slovenski standard je istoveten z: EN 14257:2019
ICS:
83.180 Lepila Adhesives
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN 14257
EUROPEAN STANDARD
NORME EUROPÉENNE
September 2019
EUROPÄISCHE NORM
ICS 83.180 Supersedes EN 14257:2006
English Version
Adhesives - Wood adhesives - Determination of tensile
strength of lap joints at elevated temperature (WATT '91)
Adhésifs - Adhésifs pour bois - Détermination de la Klebstoffe - Holzklebstoffe - Bestimmung der
résistance en traction à température élevée des joints à Klebfestigkeit von Längsklebungen im Zugversuch in
recouvrement (essai WATT '91) der Wärme (WATT'91)
This European Standard was approved by CEN on 5 August 2019.
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, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 14257:2019 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Principle . 4
5 Apparatus . 4
6 Sample preparation . 4
6.1 Preparation of the-test pieces . 4
6.2 Conditioning of the bonded assemblies . 5
7 Test procedure . 5
8 Calculation and express of results . 5
9 Test report . 5
9.1 General . 5
9.2 The adhesive . 6
9.3 Preparation of the test pieces and testing procedures . 6
9.4 Test results . 6
European foreword
This document (EN 14257:2019) has been prepared by Technical Committee CEN/TC 193 “Adhesives”,
the secretariat of which is held by UNE.
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 March 2020, and conflicting national standards shall
be withdrawn at the latest by March 2020.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 14257:2006.
In comparison with the previous edition, the following technical modifications have been made:
— Clause 4 “Principle” revised;
— 5.1 relevant to tensile testing machine revised;
— 6.1 “Preparation of the bonded test pieces”: number of the test pieces modified;
— Clause 7 “Test procedure” revised;
— 9.3 “Preparation of the test pieces and testing procedures” revised;
— 9.4 “Test results” revised.
SAFETY STATEMENT — Persons using this document should be familiar with the normal laboratory
practice, in principle. This
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