FprEN 49-1

• Abstract:

  This document specifies a method for the determination of the protective effectiveness or the toxic values of a wood preservative against infestation by Anobium punctatum (De Geer) when the product is applied as a surface treatment to wood.; This method is applicable to:; - water-insoluble chemicals that 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: 01-Dec-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 49-1:2026 - Wood preservatives - Determination of the protective effectiveness against Anobium punctatum (De Geer) by egg-laying and larval survival - Part 1: Application by surface treatment (Laboratory method)

• Revises: EN 49-1:2016 - Wood preservatives - Determination of the protective effectiveness against Anobium punctatum (De Geer) by egg-laying and larval survival - Part 1: Application by surface treatment (Laboratory method)
• Effective Date: 12-Apr-2023

FprEN 49-1 is a CEN draft European Standard for laboratory determination of the protective effectiveness or toxic values of wood preservatives against Anobium punctatum (De Geer) when the product is applied as a surface treatment to wood. It is written for laboratories and product evaluators who need to compare treated wood with untreated and solvent- or diluent-treated controls, using egg-laying, egg hatch and larval survival as the outcome measures.

What does FprEN 49-1 specify?

FprEN 49-1 specifies a laboratory method for assessing a wood preservative applied by surface treatment to wood, and it applies to both protective effectiveness and toxic values. The method can be used with water-insoluble chemicals, organic formulations, organic water-dispersible formulations and water-soluble materials such as salts, whether or not the specimens have been aged beforehand.

The document is organized into clauses covering scope, references, terms, principle, materials, sampling, test specimens, procedure, validity, result expression and test report. It also includes four informative annexes that help with reporting, insect identification, culturing and laboratory safety.

Annex	What it covers
Annex A	Example of a test report
Annex B	Identification of sex of test insects Anobium punctatum
Annex C	Culturing technique for Anobium punctatum
Annex D	Environmental, health and safety precautions within chemical/biological laboratory

What are the key requirements of FprEN 49-1?

FprEN 49-1 bases the test on comparing treated wood with controls after exposure to gravid females of Anobium punctatum. For toxic values, the standard uses several treatment concentrations and asks the laboratory to identify the loading or concentration where larvae are no longer found, and the next lower concentration where live larvae still occur.

Test organism and controls

Clause 5 requires adult Anobium punctatum in good condition, collected from naturally infested wood or laboratory culture, then checked to be active and free from mites. The adults are sexed and separated before use, which matters because the test needs controlled mating and egg laying. The test also requires untreated controls, and solvent or diluent controls when a solvent or diluent is used.

Wood and test specimens

Clause 7 specifies European oak as the reference wood species, either sessile oak or pedunculate oak. The wood must be sound sapwood with defined growth characteristics, and the specimens must be prepared to fixed dimensions and individually marked. In practice, this gives comparable specimens so that differences in infestation are more likely to come from the preservative, not from wood variability.

Clause 7.5 sets the replication at five specimens per preservative and concentration, plus five untreated controls, and five solvent or diluent controls when relevant. This matters because the result depends on enough treated and control specimens to judge the preservative effect.

Sealing, treatment and conditioning

Clause 8.1 requires conditioning before treatment, then sealing of the relevant faces depending on the application method. Water-based treatments use paraffin wax, while treatments with an organic solvent as the continuous phase use a suitable sealant that resists the product and does not repel or kill insects. The specimens are then treated by dipping, brushing or pipette, with the application rate recorded for each specimen.

After treatment, the specimens are conditioned for four weeks, and any ageing procedure according to EN 73 or EN 84 is carried out after drying. This sequence matters because the test aims to simulate treated timber after it has dried, and possibly after ageing, before infestation occurs.

Exposure and examination

Clause 8.2 and 8.3 require an egg-laying zone made with fine cloth on the unsealed face, followed by exposure in test containers with five female insects and at least five male insects. The chamber conditions and exposure period are controlled, and more insects may be added if too few eggs are laid. Clause 8.4 then requires counting eggs laid, eggs hatched and larvae, with imaging tools allowed as an additional way to examine internal tunnels.

Validity and result expression

Clause 9 accepts the test only when the control specimens yield more than 50 live larvae in total and live larvae are present in all control specimens. Clause 10 then requires results to be expressed as the number of eggs laid, eggs hatched and live larvae on each specimen. If concentration series are used, toxic values are reported as preservative loading per unit area together with the corresponding concentration of the treating solution.

Test report

Clause 11 requires a detailed report of the preservative, wood species, treatment method, concentrations, drying and ageing, exposure dates, results and any deviations. The report must also carry the note that the test report alone is not an approval certificate.

What terms does FprEN 49-1 define?

• Representative sample - a sample whose physical or chemical characteristics match the volumetric average characteristics of the total volume being sampled.
• Supplier - the sponsor of the test, meaning the person or company that provides the preservative sample to be tested.
• Protective effectiveness - the measured ability of the treated wood to reduce egg laying, egg hatch and larval survival compared with untreated controls.
• Toxic values - the preservative loadings or concentrations at which larvae are absent at one concentration and still present at the next lower one.
• Control test specimen - a comparison specimen left untreated or treated only with solvent or diluent so the test can separate preservative effect from other effects.
• Test specimen - the prepared wood piece used in the laboratory exposure and examination steps.

Who uses FprEN 49-1?

FprEN 49-1 is used by wood preservative manufacturers, test laboratories, and technical staff who evaluate surface-applied products for insect protection. It is also used by quality managers and buyers who need a laboratory basis for comparing products, checking claimed performance, or documenting toxic values for a formulation. The culturing and reporting annexes make it especially relevant to laboratories that run biological durability tests on wood and wood-based products.

What changed in FprEN 49-1 from the previous edition?

FprEN 49-1 will supersede EN 49-1:2016. The European foreword states these significant technical changes:

• sealing-face specifications for solutions with an organic solvent as the continuous phase were generalized
• temperature and humidity requirements were aligned with other insect test standards
• imaging facilities for non-destructive recording of internal insect tunnels were generalized
• storage limitations for wood used to make test specimens were deleted
• a note was added to allow optional reduction in the number of concentrations for toxic value determination
• dipping specifications were generalized and aligned with other insect standards

Which standards are used with FprEN 49-1?

Standard	What it contributes
EN 73	Accelerated ageing by evaporative ageing before biological testing
EN 84	Accelerated ageing by leaching before biological testing
EN ISO 3696	Water quality for laboratory use
EN 212	Sampling of preservatives from bulk supplies, mentioned for representative sampling
EN 49-2	The companion part for preservatives intended for impregnation rather than surface treatment
EN ISO 835-1	The pipette specification used for one application method

What does the FprEN 49-1 document contain?

The document contains a full laboratory method, not just a pass/fail statement. It gives the principle of the test, the required biological material, specimen preparation, sealing rules, treatment by dipping, brushing or pipette, drying and conditioning, insect exposure, examination, validity criteria and the way to express results.

It also includes a reporting checklist and an example report in Annex A, a figure-based guide for sexing Anobium punctatum in Annex B, and a culturing procedure in Annex C that covers culture wood, beetle collection, quarantine, infestation, culture conditions and hygiene. Annex D adds practical environmental, health and safety precautions for chemical and biological laboratory work.

SLOVENSKI STANDARD
oSIST prEN 49-1:2025
01-december-2025
Biocidni proizvodi za zaščito lesa - Ugotavljanje učinkovitosti preventivne zaščite
proti navadnemu trdoglavcu Anobium punctatum (De Geer) glede na število
odloženih jajčec in preživelih ličink - 1. del: Površinsko nanašanje (laboratorijska
metoda)
Wood preservatives - Determination of the protective effectiveness against Anobium
punctatum (De Geer) by egg-laying and larval survival - Part 1: Application by surface
treatment (Laboratory method)
Holzschutzmittel - Bestimmung der vorbeugenden Wirkung gegenüber Anobium
punctatum (De Geer) durch Beobachten der Eiablage und des Überlebens von Larven -
Teil 1: Oberflächenverfahren (Laboratoriumsverfahren)
Produits de préservation du bois - Détermination de l'efficacité protectrice vis-à-vis
d'Anobium punctatum (De Geer) par l'observation de la ponte et du taux de survie des
larves - Partie 1 : Application par traitement de surface (Méthode de laboratoire)
Ta slovenski standard je istoveten z: prEN 49-1
ICS:
71.100.50 Kemikalije za zaščito lesa Wood-protecting chemicals
oSIST prEN 49-1:2025 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN 49-1:2025
oSIST prEN 49-1:2025
DRAFT
EUROPEAN STANDARD
prEN 49-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2025
ICS 71.100.50 Will supersede EN 49-1:2016
English Version
Wood preservatives - Determination of the protective
effectiveness against Anobium punctatum (De Geer) by
egg-laying and larval survival - Part 1: Application by
surface treatment (Laboratory method)
Produits de préservation du bois - Détermination de Holzschutzmittel - Bestimmung der vorbeugenden
l'efficacité protectrice vis-à-vis d'Anobium punctatum Wirkung gegenüber Anobium punctatum (De Geer)
(De Geer) par l'observation de la ponte et du taux de durch Beobachten der Eiablage und des Überlebens
survie des larves - Partie 1 : Application par traitement von Larven - Teil 1: Oberflächenverfahren
de surface (Méthode de laboratoire) (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

EUROPÄISCHES 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 49-1:2025 E
worldwide for CEN national Members.

oSIST prEN 49-1:2025
prEN 49-1:2025 (E)
Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Principle . 7
5 Test materials . 7
5.1 Biological material . 7
5.2 Products and reagents . 7
5.3 Apparatus . 8
6 Sampling . 8
7 Test specimens . 9
7.1 Species of wood . 9
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 test specimens prior to sealing . 10
8.1.2 Sealing of the test specimen 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 . 12
8.4 Examination of the test specimens . 13
9 Validity of test . 13
10 Expression of results . 13
10.1 Assessment of the protective effectiveness . 13
10.2 Toxic values . 13
11 Test report . 14
Annex A (informative) Example of a test report . 16
Annex B (informative) Identification of sex of test insects Anobium punctatum . 18
Annex C (informative) Culturing technique for Anobium punctatum. 19
C.1 Culture wood . 19
C.1.1 Wood species . 19
C.1.2 Collection of culture wood . 19
C.1.3 Cutting of culture wood . 19
oSIST prEN 49-1:2025
prEN 49-1:2025 (E)
C.1.4 Drying of culture wood . 19
C.2 Source of beetles . 19
C.2.1 Collection of beetles . 19
C.2.2 Quarantine of beetles . 19
C.3 Infestation of culture wood . 19
C.3.1 Culture vessels . 19
C.3.2 Preparation of wood . 19
C.3.3 Introduction of beetles . 20
C.4 Culturing conditions . 20
C.4.1 Normal environment . 20
C.4.2 Natural pupation induction . 20
C.4.3 Artificial pupation induction . 20
C.5 Collection of beetles . 20
C.6 General culture hygiene . 20
Annex D (informative) Environmental, health and safety precautions within chemical/biological
laboratory . 22
Bibliography . 23

oSIST prEN 49-1:2025
prEN 49-1:2025 (E)
European foreword
This document (prEN 49-1:2025) 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 49-1:2016.
Significant technical differences between this document and EN 49-1:2016 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;
5.3.5)
c) imaging facilities for non-destructive recordings of insect tunnels inside test specimens were
generalized (5.3.10)
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 (8.1.3.2.1) 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 49-1 was published are considered as valid.
EN 49, Wood preservatives ― Determination of the protective effectiveness against Anobium punctatum (De
Geer) by egg-laying and larval survival, consists of two parts:
— Part 1: Application by surface treatment (Laboratory method);
— Part 2: Application by impregnation (Laboratory method).
EN 49-1 is required to enable effectiveness assessments of wood preservatives which are intended to be
applied by surface treatment and EN 49-2 those which are intended to be applied by impregnation.

oSIST prEN 49-1:2025
prEN 49-1:2025 (E)
Introduction
This document describes a laboratory method of testing which gives a basis for assessment of the
effectiveness of a wood preservative, when applied as a surface treatment, against Anobium punctatum. It
allows the determination of the concentration at which the product prevents the development of infestation
from egg laying. It can also be used with formulations ready for use.
This document provides information for the sealing of all but one lateral face when specimens are to be
treated by dipping.
The method simulates conditions that can occur in practice on timber which has been treated some time
previously with wood preservative applied by dip, brush or spray and on which eggs of Anobium punctatum
are laid.
This laboratory method provides one criterion by which the value of a product can be assessed. In making
this assessment the methods by which the preservative may be applied should be taken into account. It is
further recommended that results from this test should be supplemented by those from other appropriate
tests, and above all by comparison with 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 49-1:2025
prEN 49-1:2025 (E)
1 Scope
This document specifies a method for the determination of the protective effectiveness or the toxic values of
a wood preservative against infestation by Anobium punctatum (De Geer) when the product is applied as a
surface treatment to wood.
This method is applicable to:
— water-insoluble chemicals that 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 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)
oSIST prEN 49-1:2025
prEN 49-1:2025 (E)
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
— 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 gravid females of Anobium punctatum. The number of eggs laid,
the number of eggs hatched and the numbers of surviving larvae are 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
Anobium punctatum (De Geer)
Adult males and females in good condition.
Adults to be used in the test shall be collected at daily intervals from naturally infested wood or laboratory
culture (see Annex C).
Use recently emerged adults which have been recently collected; kept overnight in quarantine (see C.6); and
then checked to ensure that they are undamaged, active and free from any infestation by mites. Determine
the sex (see Annex B) of the collected and checked adults and place the males and females in separate
containers.
NOTE The proportion of males and females varies during the emergence period.
5.2 Products and reagents
5.2.1 Paraffin wax, for sealing the relevant faces of test specimens to be treated with solutions 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 Paste, for securing fine cloth (5.2.7). The paste shall be starch-free, non-toxic to Anobium punctatum
and insoluble in the product under test.
NOTE Sodium carboxy methyl cellulose, food grade, has been found to be suitable.
5.2.4 Water, complying with grade 3 of EN ISO 3696 shall be used.
oSIST prEN 49-1:2025
prEN 49-1:2025 (E)
5.2.5 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.
5.2.6 Filter paper, ordinary quality, medium-fast grade.
5.2.7 Fine cloth of a suitable material with a mesh aperture of 0,3 mm to 0,6 mm for the preparation of the
egg-laying zones.
NOTE Cotton, linen or polyamide-gauze have also been proven as suitable.
5.3 Apparatus
5.3.1 Culturing chamber, with air circulation, controlled at (21 ± 2) °C, and at relative humidity
(75 ± 5) %.
5.3.2 Conditioning chamber, well ventilated, controlled at (20 ± 2) °C and at relative humidity (65 ± 5) %.
The conditioning of test specimens may be carried out in the laboratory work area (see 5.3.4) provided that
this has the conditions specified for the conditioning chamber (see 5.3.2).
5.3.3 Treatment vessel, 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.
5.3.4 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.
5.3.5 Testing chamber, ventilated and air-conditioned, controlled at (22 ± 2) °C and at a relative humidity
of (75 ± 5) %.
5.3.6 Pipette, specified in EN ISO 835-1 shall be used, or brush.
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 Test containers, suitable for holding the test specimens and of material resistant to the solvents
used, and fitted with perforated covers to provide a good exchange of air.
NOTE Jars of approximately 60 mm diameter and 100 mm height have been found to be suitable.
5.3.9 Ordinary laboratory equipment, including a balance capable of weighing to an accuracy of 0,01 g.
5.3.10 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.
oSIST prEN 49-1:2025
prEN 49-1:2025 (E)
7 Test specimens
7.1 Species of wood
The reference species is European oak. This shall be either sessile oak (Quercus petraea (Mattuschka)
Lieblin) or pedunculate oak (Quercus robur Linnaeus).
)
Additional tests may be carried out using other species but, if so, this should be stated in the test report.
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 and having between two and ten annual rings per 10 mm.
It is recommended to use test specimens of similar growth rate within a single test.
7.3 Provision of test specimens
3)
Prepare planed strips having a cross-section of (25 ± 0,5) mm × (15 ± 0,5) mm removing a minimum of
2 mm from any surfaces exposed during drying. The longitudinal faces shall be parallel to the direction of the
grain. The annual rings shall be parallel to the broad faces (contact angle of less than 5°). 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 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
Use:
a) five 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 and each concentration;
b) five untreated control test specimens (no more than two originating from the same tree unless taken at
random from a stock of more than 500) for a complete test of any given preservative;
c) five control test specimens (no more than two originating from the same tree unless taken at random
from a stock of more than 500) treated with that solvent or
...