EN 46-1:2026

• Abstract:

  This document specifies a method for the determination of the preventive action of a wood preservative against recently hatched larvae of Hylotrupes bajulus (Linnaeus) when the preservative is applied as a surface treatment to wood.; This method is applicable to:; - water-insoluble chemicals which are being studied as active insecticides,; - organic formulations, as supplied or as prepared in the laboratory by dilution of concentrates,; - organic water-dispersible formulations as supplied or as prepared in the laboratory by dilution of concentrates, or; - water-soluble materials, for example salts.; The method is applicable whether or not the test specimens have been subjected to appropriate ageing procedures.

• Status: Not Published
• Publication Date: 24-Nov-2026
• ICS: 71.100.50 - Wood-protecting chemicals
• Technical Committee: CEN/TC 38 - Durability of wood and derived materials
• Drafting Committee: CEN/TC 38/WG 24 - Insect testing - (beetles - termites)
• Current Stage: 5060 - Closure of Vote - Formal Approval
• Start Date: 24-Sep-2026
• Due Date: 03-Feb-2027
• Completion Date: 24-Sep-2026
• Ref Project: kSIST FprEN 46-1:2026 - Wood preservatives - Determination of the preventive action against recently hatched larvae of Hylotrupes bajulus (Linnaeus) - Part 1: Application by surface treatment (Laboratory method)

• Revises: EN 46-1:2016 - Wood preservatives - Determination of the preventive action against recently hatched larvae of Hylotrupes bajulus (Linnaeus) - Part 1: Application by surface treatment (laboratory method)
• Effective Date: 12-Apr-2023

EN 46-1:2026 is a CEN laboratory test method for wood preservatives applied by surface treatment. It measures whether a preservative prevents recently hatched larvae of Hylotrupes bajulus (Linnaeus) from boring into treated wood and surviving there, so the result can be used to assess larvicidal preventive action under controlled conditions.

The method applies to water-insoluble chemicals, organic formulations, organic water-dispersible formulations and water-soluble materials such as salts. It can be used on specimens that have been aged beforehand as well as on untreated, unaged specimens.

What does EN 46-1:2026 specify?

EN 46-1:2026 specifies a laboratory method for determining the preventive action of a wood preservative against recently hatched Hylotrupes bajulus larvae when the product is applied to wood as a surface treatment. The document is organized as a full test method, from specimen preparation and insect exposure to result expression and reporting.

The main structure is:

• Clause 1 Scope
• Clause 2 Normative references
• Clause 3 Terms and definitions
• Clause 4 Principle
• Clause 5 Test materials
• Clause 6 Sampling
• Clause 7 Test specimens
• Clause 8 Procedure
• Clause 9 Expression of results
• Clause 10 Test report

Annex	What it covers
Annex A	Example of a test report
Annex B	Technique for culturing Hylotrupes bajulus
Annex C	Differentiation of heartwood and sapwood in Pinus species
Annex D	Environmental, health and safety precautions in the chemical/biological laboratory
Annex E	Slow acting and deferred effect formulations - extending the test duration

Annex E is normative and extends the method to a 24-week exposure for slow acting or deferred effect products. That matters in practice when a preservative acts slowly and the normal 12-week test would not show its full effect.

What are the key requirements of EN 46-1:2026?

EN 46-1:2026 is built around a controlled comparison between treated wood and untreated or solvent-treated controls. In practice, the method only gives meaningful results if the wood, the larvae, the treatment and the exposure conditions are all prepared consistently.

Specimens and wood quality

Clause 7 requires the reference wood species to be Scots pine (Pinus sylvestris Linnaeus). The wood must be sapwood, visually sound, and of a growth pattern suitable for the test. This matters because the larvae need a susceptible wood substrate if the preservative effect is to be measured fairly.

The specimens are made to a fixed size after conditioning, and each specimen must be identified throughout the test. Clause 7 also sets the minimum numbers of treated specimens and controls. That gives enough replication to judge whether the preservative, rather than variation in the wood, caused the observed effect.

Treatment method and sealing

Clause 8 distinguishes between brushing or pipette application on one lateral face and dipping, where all faces except one are sealed. The sealing material depends on whether water or an organic solvent is the continuous phase. This prevents unwanted uptake and keeps the test focused on the intended treated surface.

For dipping, the method requires weighing before and after treatment so the retention can be calculated. For brushing or pipette application, the applied mass or volume is also measured. In practice, this is how the test links biological performance to the actual amount of preservative on the wood.

Concentrations and toxic values

If toxic values are required, Clause 8 calls for a series of concentrations arranged around the expected effect level. The document also allows a smaller concentration series if toxic values were already determined by another standardized test method. This helps the user select an efficient test plan while still producing comparable loading data.

The toxic values are reported as preservative mass per treated wood surface, together with the corresponding treating-solution concentration. That is important for product development and comparison, because it shows not only whether the product works, but at what loading it works.

Exposure and incubation

Clause 8 requires the treated specimen to be fitted with a glass plate and a narrow gap so the larvae can start tunnelling under controlled conditions. The standard exposure period is 12 weeks. Annex E extends this to 24 weeks for slow acting or deferred effect formulations, with fewer larvae per specimen and more specimens overall.

The test chamber conditions, the conditioning of the specimens, and the culturing conditions for the larvae are all controlled. In practice, this reduces variability and makes results more repeatable between laboratories.

Examination and validity

Clause 8 requires an early examination after four weeks. The test is only valid if the controls show sufficient attack and survival. The document also allows imaging facilities, such as X-ray equipment, for examining internal tunnels, provided live and dead larvae can still be distinguished.

This is important because the result depends on both attack and survival, not just on whether larvae entered the wood.

Reporting

Clause 10 sets the minimum contents of the test report, including the product identity, active ingredient, wood species, application method, treatment conditions, drying and ageing steps, examination dates and all larval outcomes. Any deviation from the method must also be recorded. That makes the report usable for technical review, audit trail and comparison with other tests.

What terms does EN 46-1:2026 define?

• Representative sample - a sample whose physical and/or chemical characteristics match the volumetric average characteristics of the total volume sampled.
• Supplier - the sponsor of the test, meaning the person or company providing the preservative sample.
• Hylotrupes bajulus (Linnaeus) - the longhorn beetle targeted by the method; the test uses recently hatched larvae of this species.
• Control test specimens - untreated specimens, and where relevant solvent- or diluent-treated specimens, used to judge whether the test and the preservative behaved as expected.
• Toxic values - the preservative loadings that separate complete larval death from concentrations where live larvae still occur.
• Ageing procedure - a preparatory treatment, such as EN 73 or EN 84, used before biological testing to simulate prior exposure.
• Retention - the amount of preservative retained per unit area of treated wood surface after application.

Who uses EN 46-1:2026?

EN 46-1:2026 is used by laboratories that test wood preservatives, by manufacturers developing insecticidal formulations for wood protection, and by quality teams that need comparable performance data. It is also relevant to technical staff responsible for product evaluation, product registration support, and internal or external verification testing.

The method is especially useful when a preservative is intended for surface treatment and when the user wants to know whether larvae can penetrate the treated face and survive in the untreated wood below. Labs culturing Hylotrupes bajulus also use Annex B as practical guidance for maintaining the insect colony.

What changed in EN 46-1:2026 from the previous edition?

The foreword says this edition supersedes EN 46-1:2016. It lists these technical changes:

• sealing specifications for specimens treated with solutions in which an organic solvent is the continuous phase were generalized
• temperature and humidity requirements were aligned with other insect test standards
• imaging facilities for non-destructive recording of internal tunnels were generalized
• storage limitations for wood used to make specimens were deleted
• a note was added allowing fewer concentrations when determining toxic value
• dipping specifications were generalized and aligned with other insect standards

The foreword also states that test results obtained according to earlier versions, or tests already started before this edition was published, are considered valid.

Which standards are used with EN 46-1:2026?

Standard	Contribution
EN 73	Accelerated ageing by evaporation before biological testing
EN 84	Accelerated ageing by leaching before biological testing
EN ISO 3696	Water quality for analytical laboratory use
EN ISO 835	Graduated pipettes for applying treatment solutions
EN 212	Sampling of wood preservatives from bulk supplies
EN 46-2	Companion part covering the ovicidal effect against Hylotrupes bajulus
EN 47	Related laboratory method for toxic values against Hylotrupes bajulus in totally impregnated wood

What does the EN 46-1:2026 document contain?

EN 46-1:2026 contains the full laboratory procedure, including specimen selection, sealing, treatment by brushing, pipette or dipping, exposure set-up, and the rules for counting live and dead larvae. It also includes a figure showing the glass-plate arrangement used to create the larval entry gap.

The annexes add practical support material rather than changing the basic method. Annex A gives a model report, Annex B explains insect culturing, Annex C gives a simple chemical spot test for identifying heartwood and sapwood in Pinus species, and Annex D gives laboratory safety guidance. Annex E provides the longer test schedule for slow acting formulations.

SLOVENSKI STANDARD
oSIST prEN 46-1:2025
01-december-2025
Biocidni proizvodi za zaščito lesa - Ugotavljanje preventivnega delovanja proti
hišnemu kozličku Hylotrupes bajulus (Linnaeus) - 1. del: Ugotavljanje
učinkovitosti proti ličinkam (laboratorijska metoda)
Wood preservatives - Determination of the preventive action against recently hatched
larvae of Hylotrupes bajulus (Linnaeus) - Part 1: Application by surface treatment
(Laboratory method)
Holzschutzmittel - Bestimmung der vorbeugenden Wirkung gegenüber frisch
geschlüpften Larven von Hylotrupes bajulus (Linnaeus) - Teil 1: Anwendung durch
Oberflächenverfahren (Laboratoriumsverfahren)
Produits de préservation du bois - Détermination de l'action préventive contre les larves
récemment écloses d'Hylotrupes bajulus (Linnaeus) - Partie 1 : Application par
traitement de surface (Méthode de laboratoire)
Ta slovenski standard je istoveten z: prEN 46-1
ICS:
71.100.50 Kemikalije za zaščito lesa Wood-protecting chemicals
oSIST prEN 46-1:2025 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN 46-1:2025
oSIST prEN 46-1:2025
DRAFT
EUROPEAN STANDARD
prEN 46-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2025
ICS 71.100.50 Will supersede EN 46-1:2016
English Version
Wood preservatives - Determination of the preventive
action against recently hatched larvae of Hylotrupes
bajulus (Linnaeus) - Part 1: Application by surface
treatment (Laboratory method)
Produits de préservation du bois - Détermination de Holzschutzmittel - Bestimmung der vorbeugenden
l'action préventive contre les larves récemment écloses Wirkung gegenüber frisch geschlüpften Larven von
d'Hylotrupes bajulus (Linnaeus) - Partie 1 : Application Hylotrupes bajulus (Linnaeus) - Teil 1: Anwendung
par traitement de surface (Méthode de laboratoire) durch Oberflächenverfahren
(Laboratoriumsverfahren)
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 38.
If this draft becomes a European Standard, 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.

This draft European Standard was established by CEN 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, Türkiye and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATIO N

E U R O P Ä I SC H E S KOMITEE FÜR NORMUN G

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 46-1:2025 E
worldwide for CEN national Members.

oSIST prEN 46-1:2025
prEN 46-1:2025 (E)
Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Principle . 6
5 Test materials . 7
5.1 Biological material . 7
5.2 Products and reagents . 7
5.3 Apparatus . 7
6 Sampling . 8
7 Test specimens . 8
7.1 Species of wood . 8
7.2 Wood quality . 9
7.3 Provision of test specimens . 9
7.4 Dimensions of test specimens . 9
7.5 Number of test specimens . 9
8 Procedure. 10
8.1 Preparation of the test specimens . 10
8.1.1 Conditioning of the test specimens prior to sealing . 10
8.1.2 Sealing of the transverse faces . 10
8.1.3 Treatment of the test specimens . 10
8.1.4 Drying and conditioning of the test specimens after treatment . 12
8.2 Exposure of the test specimens to the insects . 12
8.3 Conditions and duration of the test . 13
8.4 Examination of the test specimens . 13
8.4.1 Examination . 13
8.4.2 Validity of the test . 14
9 Expression of results . 14
9.1 Evaluation of attack . 14
9.2 Toxic values . 14
10 Test report . 15
Annex A (informative) Example of a test report . 17
Annex B (informative) Technique for culturing Hylotrupes bajulus (Linnaeus) . 19
B.1 General . 19
B.2 Obtaining parent beetles . 19
B.3 Mating . 19
B.4 Egg-Iaying . 19
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prEN 46-1:2025 (E)
B.5 Hatching of eggs . 20
B.6 Larval development . 20
B.7 Enemies and parasites . 21
Annex C (informative) Differentiation of heartwood and sapwood in Pinus species . 22
C.1 Principle . 22
C.2 Reagents . 22
C.3 Apparatus . 22
C.4 Procedure . 22
Annex D (informative) Environmental, health and safety precautions within
chemical/biological laboratory . 23
Annex E (normative) Slow acting and deferred effect formulations – Extending the test
duration . 24
Bibliography . 26

oSIST prEN 46-1:2025
prEN 46-1:2025 (E)
European foreword
This document (prEN 46-1:2025) has been prepared by Technical Committee CEN/TC 38 “Biological
durability of wood and wood-based products”, the secretariat of which is held by SIS.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 46-1:2016.
Significant technical differences between this document and EN 46-1:2016 are as follows:
a) specifications for sealing faces of test specimens to be treated with solutions in which an organic
solvent is the continuous phase were generalized (5.2.2);
b) requirements for temperature and humidity were aligned with other insect test standards (5.3.1;
5.3.4; B5; B6);
c) imaging facilities for non-destructive recordings of insect tunnels inside test specimens were
generalized (5.3.11);
d) storage limitations for wood from which test specimens are to be made from were deleted (7.2);
e) a note was added to 8.1.3.1.3 to optionally reduce the number of concentrations which are
necessary to determine the toxic value;
f) Specifications for dipping (8.1.3.3) were generalized and aligned with other insect standards.
NOTE Test results obtained according to earlier versions of this document or when the tests had started
before this version of EN 46-1 was published are considered as valid.
The standard EN 46 is composed of two parts:
— EN 46-1, Wood preservatives ― Determination of the preventive action against recently hatched
larvae of Hylotrupes bajulus (Linnaeus) ― Part 1: Application by surface treatment (laboratory
method)
— EN 46-2, Wood preservatives ― Determination of the preventive action against recently hatched
larvae of Hylotrupes bajulus (Linnaeus) ― Part 2: Ovicidal effect (laboratory method)
EN 46 consists of two parts to enable preventive action of wood preservatives, against recently hatched
larvae of Hylotrupes bajulus, which are intended to be applied by surface treatment; Part 1 is required to
determine the larvicidial effect of preservatives and Part 2 is required to determine the ovicidal action
of the preservatives after egg-laying of young females.

oSIST prEN 46-1:2025
prEN 46-1:2025 (E)
Introduction
This document describes a laboratory method of testing which gives a basis for the assessment of the
preventive action of a wood preservative, when applied as a surface treatment, against recently hatched
larvae of Hylotrupes bajulus, whereas the method for determining the toxic values against Hylotrupes
bajulus (EN 47) provides a means of checking whether a preservative prevents attack by these larvae
and prevents their survival within totally impregnated wood.
This document provides information for the sealing of all but one lateral face when specimens are to be
treated by dipping.
This method makes it possible to determine whether recently hatched larvae are capable of boring
through the treated surface of a susceptible wood species and of surviving in the untreated part of the
test specimen. For this purpose, the procedure seeks to reproduce normal egg-laying conditions
existing in cracks in wood, which provide the principal egg-laying sites. It takes account of the fact that,
if larvae pass through the treated surface, they will then tunnel in the direction of the least protected
regions of the wood.
This laboratory method provides one criterion by which the value of a preservative can be assessed. In
making this assessment, the methods by which the preservative may be applied should be taken into
account. This test is of particular interest when applied to test specimens which have been subjected to
an ageing procedure. It is further recommended that results from this test should be supplemented by
those from other appropriate tests and, above all, by practical experience.
When products which are very active at low concentrations are used it is very important to take
suitable precautions to isolate and separate, as far as possible, operations involving chemical products,
other products, treated wood, laboratory apparatus and clothing. Suitable precautions should include
the use of separate rooms, areas within rooms, extraction facilities, conditioning chambers and special
training for personnel (see also Annex D for environmental, health and safety precautions).

oSIST prEN 46-1:2025
prEN 46-1:2025 (E)
1 Scope
This document specifies a method for the determination of the preventive action of a wood preservative
against recently hatched larvae of Hylotrupes bajulus (Linnaeus) when the preservative is applied as a
surface treatment to wood.
This method is applicable to:
— water-insoluble chemicals which are being studied as active insecticides;
— organic formulations, as supplied or as prepared in the laboratory by dilution of concentrates;
— organic water-dispersible formulations as supplied or as prepared in the laboratory by dilution of
concentrates;
— water-soluble materials, for example salts.
The method is applicable whether or not the test specimens have been subjected to appropriate ageing
procedures.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
EN 73, Durability of wood and wood-based products — Accelerated ageing of treated wood prior to
biological testing — Evaporative ageing procedure
EN 84, Durability of wood and wood-based products — Accelerated ageing of treated wood prior to
biological testing — Leaching procedure
EN ISO 3696, Water for analytical laboratory use — Specification and test methods (ISO 3696)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
representative sample
sample having its physical and/or chemical characteristics identical to the volumetric average
characteristics of the total volume being sampled
3.2
supplier
sponsor of the test (person or company providing the sample of wood preservative to be tested)
4 Principle
Depending on the test being carried out either:
— on a set of test specimens of a susceptible wood species that is surface treated with a solution of the
preservative; or
oSIST prEN 46-1:2025
prEN 46-1:2025 (E)
— if toxic values are to be determined, on several sets of test specimens of a susceptible wood species
that are surface treated with a series of solutions in which the concentration of preservative is
ranged in a given progression.
The treated test specimens are exposed to recently hatched larvae of Hylotrupes bajulus. The resulting
attack is observed and compared with those in untreated control test specimens. If the preservative has
been prepared in the laboratory by dilution of a concentrate or by dissolution of a solid, the resulting
attack is also compared to that in solvent or diluent treated control test specimens.
5 Test materials
5.1 Biological material
5.1.1 Hylotrupes bajulus (Linnaeus) larvae, within three days of hatching.
5.1.2 Source of larvae. Obtain the larvae from cultures reared, e. g. as described in Annex B.
5.1.3 Provision of larvae. Collect larvae from eggs laid by different females.
5.1.4 Choice of larvae. Use a mixed batch of these larvae for the test. Use ten larvae per treated test
specimen or control test specimen.
5.2 Products and reagents
5.2.1 Paraffin wax, for fixing the glass plate and for sealing the end faces as well as all relevant other
faces of test specimens to be treated with solutions in all cases in which water is the continuous phase
(see 8.1.2.1 and 8.1.2.2).
NOTE Paraffin wax with a setting point of approx. 52 °C to 54 °C has been found to be suitable.
5.2.2 Sealant, for sealing the end faces and all relevant other faces of test specimens to be treated with
solutions in all cases in which an organic solvent is the continuous phase (see 8.1.2.1 and 8.1.2.3). The
sealant must be resistant to penetration by the wood preservative under test and the respective solvent.
The sealant must not act repellent or insecticidal in the test specimen.
NOTE Gelatine or two to three coats of a two-component epoxy varnish with a drying step between each coat
has been found to be suitable.
5.2.3 Water, complying with grade 3 of EN ISO 3696 shall be used.
5.2.4 Solvent or diluent, a volatile liquid that will dissolve or dilute the preservative but does not
leave a residue in the wood at the end of the post-treatment conditioning period that has a toxic effect
on the insects.
CAUTION — Do not use benzene or other solvents which pose a health risk.
5.3 Apparatus
5.3.1 Culturing chamber, with air circulation, and controlled at 26± 2 °C and at a relative humidity of
(75 ± 5) %.
5.3.2 Conditioning chamber, well ventilated and controlled at (20 ± 2) °C and at a relative humidity
of (65 ± 5) %.
oSIST prEN 46-1:2025
prEN 46-1:2025 (E)
The conditioning of test specimens may be carried out in the laboratory work area (see 5.3.3) provided
that this has the conditions specified for the conditioning chamber (see 5.3.2).
5.3.3 Laboratory work area, well ventilated, where treatment of the test specimens is carried out.
CAUTION — It is essential to follow safety procedures for handling flammable and toxic
materials. Avoid excessive exposure of operators to solvents or their vapours.
5.3.4 Testing chamber, ventilated and air conditioned, controlled at (22 ± 2) °C and at a relative
humidity of (75 ± 5) %.
5.3.5 Treatment vessels of a material that does not react with the preservative under test, for
example of glass for organic products and of polyethylene for salts containing fluorine.
5.3.6 Weights, to provide ballast for the test specimens.
The weights shall not react with any materials with which they come into contact during the test.
5.3.7 Safety equipment, protective clothing, protective gloves appropriate for the test product
and the test solvent, to ensure the safety of the operator.
5.3.8 Glass plates, (48 ± 1) mm long and (25 ± 1) mm wide, intended to provide a lateral slit on the
test specimens.
5.3.9 Ordinary laboratory equipment, including a balance capable of weighing to an accuracy of
0,01 g.
5.3.10 Pipette, specified in EN ISO 835 shall be used, or brush.
5.3.11 Imaging facilities e. g. X-ray apparatus, or any other device that offers good images (2D), of
internal tunnels caused by small larvae.
6 Sampling
The sample of preservative shall be representative of the product to be tested. Samples shall be stored
and handled in accordance with any written recommendations from the supplier.
For the sampling of preservatives from bulk supplies, the procedure given in EN 212 should be used.
7 Test specimens
7.1 Species of wood
)
The reference species is Scots pine (Pinus sylvestris Linnaeus) .
Additional tests may be carried out using other species but, if so, this should be stated in the test report.

1)
In southern European countries the pine species most frequently infested by Hylotrupes bajulus may be used as an
alternative, provided that the suitability of the species for use in the tests specified in this document has been demonstrated in
all aspects (development of larvae, resistance to impregnation, etc.).
oSIST prEN 46-1:2025
prEN 46-1:2025 (E)
7.2 Wood quality
The wood shall be free from visible cracks, stain, decay, insect damage and other defects. The wood
shall not have been water-stored, floated, chemically treated or steamed. The wood shall originate from
trees preferably felled in winter. The trees shall be cut immediately after felling and the timber rapidly
air-dried or kiln dried at temperatures below 60 °C.
The wood shall be exclusively sapwood containing little resin and having between 2,5 and 8 annual
rings per 10 mm. The proportion of latewood in the annual rings shall not exceed 30 % of the whole.
It is recommended to use test specimens of similar growth rate within a single test.
)
7.3 Provision of test specimens
Prepare planed strips having a cross-section of (25 ± 0,5) mm × (15 ± 0,5) mm removing a minimum of
2 mm from any faces exposed during drying. The longitudinal faces shall be parallel to the direction of
the grain. The annual rings shall have a contact angle of 45° ± 15° to the broad faces. Make transverse
cuts, neatly to give sharp edges and a fine-sawn finish to the end-grain surfaces, to give test specimens
(50 ± 0,5) mm long.
The test specimens shall originate from a minimum of three trees or shall be taken at random from a
stock originally of more than 500 test specimens.
7.4 Dimensions of test specimens
The dimensions of each test specimen after reaching equilibrium in the conditioning chamber (5.3.2)
shall be (50 ± 0,5) mm × (25 ± 0,5) mm × (15 ± 0,5) mm.
Mark each test specimen so that it can be identified throughout the test.
7.5 Number of test specimens
a) Six treated test specimens (no more than two originating from the same tree unless taken at
random from a stock of more than 500) for each preservative, each concentration and each
duration of treatment;
b) Three untreated control test specimens (each originating from a different tree unless taken at
random from a stock of more than 500) for a complete test of any given preservative;
c) Three control test specimens treated with the solvent or diluent (5.2.3 or 5.2.4) (each originating
from a different tree unless taken at random from a stock of more than 500) if a solvent or diluent
(including water) is used.
Control test specimens under c) may be omitted if the solvent or diluents is water of drinking quality.
When dipping is to be used (8.1.3.3) it is advisable to treat more than the specified number of test
specimens so that, after weighing, any test specimens with abnormally high or low retentions can be
rejected from the batch.
To gain further information on a formulation the manufacturer may find it useful to test a version of the
preservative where the active ingredient(s) has been removed.

2)
For special tests, test specimens may be obtained according to a given series. As a result, it may be preferable to take test
specimens from pretreated strips. Where pretreated strips are used details should be included in the test report.
oSIST prEN 46-1:2025
prEN 46-1:2025 (E)
8 Procedure
8.1 Preparation of the test specimens
8.1.1 Conditioning of the test specimens prior to sealing
Allow the test specimens to condition in the conditioning chamber (5.3.2) for a minimum of two weeks.
8.1.2 Sealing of the test specimen faces
8.1.2.1 General
When treatment is to be by brushing or by pipette then only the transverse faces of test specimens shall
be sealed. When treatment is to be by dipping then all faces, except one 25 mm × 50 mm face, shall be
sealed. The material used for sealing shall be resistant to the penetration of wood preservatives under
test. The sealings specified in 8.1.2.2 and 8.1.2.3 have been proven as suitable.
8.1.2.2 For tests with solutions in which water is the continuous phase, apply three coats of the
paraffin wax (5.2.1) at about 90 °C so that the first coat adheres closely to the wood and the successive
coatings bond to one another. Condition the sealed test specimens in the conditioning chamber (5.3.2)
for at least one day.
8.1.2.3 For tests with preservative solutions in which the continuous phase is an organic
solvent that dissolves paraffin wax, use a suitable sealant (5.2.2).
When gelatine is used, apply the first coat as an aqueous solution of 200 g/l at 40 °C, then after a
minimum of 8 h of drying, apply two further coats of an aqueous solution of 300 g/l at 50 °C.
Condition the sealed test specimens in the conditioning chamber (5.3.2) for at least one day.
8.1.3 Treatment of the test specimens
8.1.3.1 Preparation of the treatment solutions
8.1.3.1.1 Solid preservatives
— Water-soluble preservatives:
Dissolve the preservative in the water (5.2.3) to the required concentration, or in a series of
concentrations if toxic values are to be determined.
— Non-water-soluble preservatives:
Dissolve the preservative in an appropriate solvent (5.2.4) to the required concentration, or in a series
of concentrations if toxic values are to be determined.
All treatment solutions shall be freshly prepared.
8.1.3.1.2 Liquid preservatives
If appropriate, use the preservative without further preparation other than any necessary stirring. If it
is a concentrate or if toxic values are to be determined, dilute the preservative with the diluent to the
required working concentration, using the procedure specified by the manufacturer.
If available, a formulation of the preservative to be tested without active substances may also be
included in the test.
All treatment solutions shall be freshly prepared.
oSIST prEN 46-1:2025
prEN 46-1:2025 (E)
8.1.3.1.3 Toxic values
If toxic values are to be determined, prepare a series of at least five concentrations by mass, distributed
evenly about the expected toxic values.
If a toxic value had been determined by other standardised test methods, a series of three
concentrations by mass, distributed evenly about the expected toxic values may be sufficient.
A solvent or diluent control, i. e. treatment at concentration = 0, shall also be used. If the ap
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