SIST-TP CEN/TR 14723:2005

SLOVENSKI STANDARD
01-marec-2005
Odpornost lesa in lesnih proizvodov - Terenski preskusi in preskusi s pospešenim
kondicioniranjem (FACT) zaščitnih sredstvev za les brez stika z zemljo
Durability of wood and wood-based products - Field and accelerated conditioning tests
(FACT) for wood preservative out of ground contact
Dauerhauftigkeit von Holz und Holzwerkstoffen - Freiland- und beschleunigte
Alterungsprüfverfahren (FACT)
Durabilité du bois et des matériaux dérivés du bois - Essais de champ et de
conditionnement accéléré (FACT) pour les produits de préservation du bois hors contact
du sol
Ta slovenski standard je istoveten z: CEN/TR 14723:2003
ICS:
71.100.50 Kemikalije za zaščito lesa Wood-protecting chemicals
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

TECHNICAL REPORT
CEN/TR 14723
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
December 2003
ICS 71.100.50
English version
Durability of wood and wood-based products - Field and
accelerated conditioning tests (FACT) for wood preservative out
of ground contact
Durabilité du bois et des matériaux dérivés du bois – Dauerhauftigkeit von Holz und Holzwerkstoffen – Freiland-
Essais de champ et de conditionnement accéléré (FACT) und beschleunigte Alterungsprüfverfahren (FACT)
pour les produits de préservation du bois hors contact du
sol
This Technical Report was approved by CEN on 26 November 2003. It has been drawn up by the Technical Committee CEN/TC 38.
CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and United
Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2003 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 14723:2003 E
worldwide for CEN national Members.

Contents
1 Scope . 4
2Acronyms. 5
3 Description of the project, background and objectives . 5
4 Project contributors and roles. 6
5 Core task 1 part A: weathering cycles (EUC 1, 2 and 3), superficial treatments. 7
5.1 Introduction . 7
5.2 Aims and objectives . 8
5.3 Deliverables. 9
5.4 Material and methods . 9
5.5 Results and discussion. 10
5.6 Conclusions. 14
6 Core task 1 Part B: Weathering cycles (EUC 3), impregnation treatments . 14
7 Core task 2: a field study of preservative treated wood in EUC 3 (lap-joint test) . 17
7.1 Introduction . 17
7.2 Aims and objectives . 18
7.3 Deliverables. 18
7.4 Materials and methods . 18
7.5 Results and discussion. 20
7.6 Conclusions. 25
7.7 Sub-task 2.1: Chemical analysis of lap-joints. 26
7.8 Sub-task 2.2: Microbial ecology . 35
7.9 Sub-task 2.3: Suitability of lap-joints for composites. 36
7.10 Sub-task 2.4: Natural durability. 49
7.11 Sub-task 2.5: COST climate index: effect of local climate on decay (P2) . 50
7.12 Sub-task 2.6: Moisture measurements in lap-joints (partner 15 ). 51
7.13 Sub-task 2.7: Leaching of solubles in EUC 2 temporarily exposed to EUC 3 . 53
8 Core task 3: microbiological preconditioning for EUC 3. 54
8.1 Objectives. 54
8.2 Description of task. 54
8.3 Outputs . 55
8.4 Introduction . 55
8.5 Sub-task 3.1: Superficially treated specimens . 55
8.6 Sub-task 3.2: Impregnated test blocks . 61
9 Core task 4: preconditioning in relation to EUC 4 and related field ecology studies (combined
report of sub-tasks 4.1 and 4.2). 67
9.1 Objectives. 67
9.2 Description of the task . 67
9.3 Outputs . 67
9.4 Sub-tasks 4.1 and 4.2 . 67
Bibliography . 72
page
Foreword
This document (CEN/TR 14723:2003) has been prepared by Technical Committee CEN/TC 38 “Durability of wood
and wood-based products”, the secretariat of which is held by AFNOR.
This status of this document as Technical Report has been chosen because its content is the result of the
co-normative research as field tests for wood preservatives out of ground contact in conjunction with methods for
preconditioning test specimens prior to test.
This co-normative research has been undertaken in the framework of the SMT Project: F.A.C.T SMT4 CT96 2135.
(Co-ordinators: Dr D.J. DICKINSON and Dr S. MOLNAR from Imperial College of Science, Technology and
Medicine (London)).
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to announce this Technical Report : Austria, Belgium, Czech Republic, Denmark, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal,
Slovakia, Spain, Sweden, Switzerland and the United Kingdom.
1 Scope
This Technical Report presents a summary of the research of the S.M.T. Project: F.A.C.T, SMT4 CT96 2135. As
such it details the supporting information for the proposals for a new conditioning standard to replace EN 73 and
EN 84 and for modification and validation of ENV 12037. The full report is presented and referenced to Technical
annexes, which are available on request.
The FACT project involved the study of the fate of chosen wood preservatives in field and laboratory tests and the
affect on biological performance. The work consisted of four core tasks and associated sub-tasks designed to
provide the scientific background to the proposals made.
 Task 1
This consisted of a study of artificial weathering techniques for the conditioning of treated test blocks prior to
biological test. It was originally hoped that it might be possible to relate different weathering cycles to the different
climatic conditions found within Europe. However this did not prove possible but it is possible to recommend a
single weathering cycle to replace the use of EN 73 and EN 84. A draft experimental standard has been prepared
based on the findings of this work.
All the supporting data and associated studies are summarised in this Technical report in clauses 5 and 6.
 Task 2
This task consisted of an extensive field test based on ENV 12037 and associated sub-tasks. The method proved
very robust but significant modifications are recommended and the ENV is to be redrafted in the light of results
contained in this report. This field test should be considered as ‘simulated service trial’ rather than an accelerated
field test; a concept that needs careful consideration within the EN 599 framework.
Sub-tasks 2.3 and 2.4 examined the suitability of the method for composites and the testing of naturally durable
timbers. At this stage it is too early to make recommendation for their inclusion in the standard but the results look
promising and the method will probably be modified at a later revision.
 Tasks 3 and 4
These tasks examined the role of bio-conditioning of test samples in ‘use class’ 3 and 4. The results are presented
in clauses 8 and 9 and clearly indicate the importance of this subject. It is recommended that urgent attention is
given to taking this work further particularly for the testing of organic based preservatives. Although not yet ready
for standardisation, the results presented here will prove invaluable to industry in designing development
programmes for the new generation of organic based preservatives.
In summary:
 a new experimental standard will be produced to replace EN 73 and EN 84 for the physical conditioning of test
blocks;
 ENV 12037 will be modified to take into account the extensive findings of the project;
 the use of ENV 12037 for natural durability and composite testing will be considered when more results are
available;
 further work on biological conditions is urgently recommended.
2 Acronyms
a.i Active ingredient (biocide)
EUC European Use Class
HDO N-Cyclohexyldiazeniumdioxid
UC use class
ICP induction coupled plasma atomic emission spectroscopy
m.c or MC moisture content
m/m mass/mass
nr of reps number of replicates
OSB oriented strand board
QUV UV artificial weathering machine manufactured by Q-panel Co. Cleveland, Ohio, USA
r.h relative humidity
SD standard deviation
TM
trademark
TBTO/TnBTO tri n-butyltin oxide
UVS-Cabinet cabinet with UV-light and spray option for artificial weathering of treated wood
WHC water holding capacity
WMC wood moisture content in %
3 Description of the project, background and objectives
CEN TC38 WG25 (ex WG 5) has clearly identified important gaps in the test methods necessary for testing wood
preservatives. There is an urgent need for new wood preservatives, particularly in the above ground, exposed
situation, (Use Class 3). No suitable field test exists for this use class for unpainted timber. Also current
pre-conditioning systems are inadequate and in some cases are not relevant to certain use classes or industry’s
needs. There exists therefore, a need to establish a suitable field test and a single progressive, preconditioning
system suitable for each of the use classes in which construction timbers are exposed. The development of new,
environmentally safe wood preservatives is urgently needed as the pressure on the older systems increases and the
use of durable, tropical timbers become less acceptable.
In summary the objectives consist of:
a) to identify and quantify the role of leaching, light, hydrolysis and non-decay, biological factors in the long term
performance of wood preservatives. These factors are to be related directly to the specific European Use
Classes i.e.:
 EUC 1 (Dry timber in building, subjected to insect attack);
 EUC 2 (Timber in building subjected to occasional wetting and at risk from insects and brown rot fungi);
 EUC 3 (Timber exposed to the weather but out of ground contact and subject to insect and fungal decay
from both white and brown rot fungi);
 EUC 4 (Timber in ground contact or fresh water and subject to all biological agencies of attack including
soft-rot fungi);
The important factor studied will be related directly to the fate of the preservative in the field and to the existing
biological test relevant to each use class.
b) to study accelerated ageing procedures and biological preconditioning procedures capable of reproducing the
ageing effects occurring in practice. This will be done by studying the losses and changes of chosen
preservatives in comparison to field data. This will then enable schedules and procedures to be defined in
order to simulate natural long term exposure of preservative treated wood;
c) to prepare a technical case to recommend specific ageing and preconditioning cycles suitable to be used as
standard laboratory procedures for accelerated ageing of treated wood samples, prior to biological test.
4 Project contributors and roles
P1.Imperial College of Science, Technology and Medicine (IMPCOL) UK
Partner 1 (IMPCOL) was responsible for co-ordinating the project. They acted as a site for the field test in order to
provide identical conditions for their work in Task 3 concerned with bio-preconditioning. They were also responsible
for studying bio-conditioning in EUC 4. Both these tasks were long term and fed directly from the work of the other
participants. (Core tasks 2, 3 and 4; Sub-task 2.5).
P2. Building Research Establishment (BRE) UK
Partner 2 (BRE) was responsible for carrying out the fundamental laboratory work on the stability of insecticides in
EUC 1 and 2. This work helped identify the true role of associated factors in the loss of efficacy and underpin the
laboratory weathering trials. (Sub-tasks 1.1 and 2.5).
P3. TNO. Building Construction Research (T.N.O) Netherlands
Partner 3 (TNO) took responsibility for the laboratory weathering trials with TnBTO and also for the chemical
analysis of this preservative in the field trials. They exposed superficially treated samples in the lap-joint trial and
also studied natural durability of imported timbers in the lap-joint trial. They also co-operated with P15 on M/C
studies.(Core tasks 1 (b) and 2; Sub-tasks 2.1, 2.4 and 2.6).
P4. Bundesanstalt für Materialforschung und -prüfung (BAM) Germany
Partner 4 (BAM) was a key partner in laboratory weathering trials. They assumed responsibility for the
organo-metallic preservative in both the laboratory and field trials in co-operation with their industrial partner
(Wolman). They also exposed superficially treated lap-joints and conducted ecological studies on these joints. They
also compared the laboratory ageing procedures to the German RAL tests in an associated trial funded nationally.
They also carried out bio-preconditioning trials with superficially treated timber. Partner 4 co-ordinated the field
trials.(Core tasks 1 (b), 1.2 and 2; Sub-tasks 2.1, 2.2 and 3.1).
P5. Universiteit Ghent (RUG) Belgium
Partner 5 (RUG) was responsible for the laboratory trials and field trials with regard to the triazole preservative.
This was in co-operation with their industrial partner, Janssen.(Core tasks 1 (b) and 2; Sub-task 2.1).
P6. Centre Technique du Bois et de l’Ameublement (CTBA) France
Partner 6 (CTBA) exposed field trials in two sites with impregnated joints. They will also carried out mild leaching
procedures for EUC 2. (Core task 2; Sub-task 2.7).
P7. Swedish University of Agricultural Sciences. Department of Wood Science (Formerly: Department of
Forest Products). (SLU)Sweden
Partner 7 (SLU) exposed impregnated lap-joints and carried out ecological studies of the joints. They also exposed
natural durability trials in parallel. SLU also co-operated with P1 in the bio-preconditioning work in EUC 4, where
they provided the essential field data from their field sites. (Core tasks 2 and 4; Sub -tasks 2.2 and 2.4).
P8. Janssen Pharmaceutica (Janssen) Belgium
Partner 8 (Janssen) provided the technical knowledge on the triazole preservative and co-operated with P5 (RUG)
in this respect. (Core tasks 1 (b), 2 and 2.1)
P9. Borax Europe (Borax) UK
Partner 9 (BORAX) was responsible for carrying out a lap-joint test with borates in order to provide the data on
early losses of soluble preservatives intended for EUC 2, but exposed to weathering during construction.
(Sub-task 2.7).
P10. Holzforschung Austria (formerly: Austrian Forest Products Laboratory) (HFA) Austria
Partner 10 (AHF1) exposed superficially treated lap-joints and ran a parallel trial with Spruce joints which they
funded locally. (Core task 2).
P11. Technical Research Centre of Finland (VTT) Finland
Partner 11 (VTT) will provided the Northern exposure site for the impregnated lap-joint trial.
P12. Dr. Wolman GmbH (Wolman) Germany
Partner 12 (Wolman) provided the technical expertise on the organo-metallic preservative in co-operation with
Partner 4. (BAM).(Core task 1 (b); Sub-task 2.1).
P13. Eidgenössische Materialprüfungs- und Forschungsanstalt (EMPA) Switzerland
Partner 13 (EMPA) carried out most of the laboratory work on the conditioning test with insecticides and
superficially treated fungicides. This major part of the project was funded by the Swiss Government. Partner 13
also helped to co-ordinate the laboratory work for the consortium. (Core tasks 1 (a), 1(b) and 1.2).
P14. Bundesforschungsanstalt für Forst-und Holzwirtschaft (BFH) Germany
Partner 14 (BFH) was solely responsible for the work on the lap-joint and weathering tests with regard to
composites. (Sub-task 2.3).
P15. SHR Hout Research (SHR) Netherlands
Partner 15 (SHR) was responsible for carrying out critical moisture content studies of the lap-joints and relating
these to actual profiles in use. (Sub-task 2.6).
5 Core task 1 part A: weathering cycles (EUC 1, 2 and 3), superficial treatments
5.1 Introduction
The aim within Core Task 1 was to find accelerated artificial ageing procedures for EUC 1 to 3, which can replace
the long natural weathering time prior to the biological test.
The results of Core Task 1 will be described in three parts, entitled "Model Compounds" (P2: Sub-task 1.1.1),
"Superficial Treated Wood" (P13: Task 1 A, Sub-Task 1.1 and 1.2) and ”Pressure Treated Wood” (P5: Task 1 B).
This new classification of Core Task 1 has been chosen to allow the logical assessment and interpretation of the
different treatments and ageing procedures.
Both reports by P13 and P5 will refer to the Sub-tasks, previously known as 1A, 1B, and to Sub-task 1.2.
For the development of an artificial ageing method it is expected that it is only a model procedure for homologation
and approval of wood preservatives in Europe, analogous to EN 73 and EN 84. It can never be a representative
pattern of the different climatic zones in Europe. It needs to be validated and calibrated subsequently in every
single climatic zone. If a factorial difference exists between the biological data after artificial and natural ageing in
defined climatic zones, the factor, which determines the application level of the wood preservative or of the content
of active ingredients (a.i) should be taken into consideration.
In the following project two terms are distinguished: "Artificial ageing" is a generic term for all the procedures, which
aim at accelerated ageing of the wood treatment. It includes all the methods for climatic simulations in the different
hazard classes (EUC) 1 to 5. "Artificial weathering" includes only the methods, which aim at accelerated ageing
combined with sprinkling. They are destined to simulate the weathering conditions in EUC 3.
5.2 Aims and objectives
The aim within Core Task 1 was to find model methods which allow the accelerated ageing of superficial and
pressure treated wood prior to the biological test and to simulate outdoors conditions in EUC 1 to 3.
According to the Technical Annex of project CT96 2135. The detailed aims of Core Task 1 are:
a) establish a suitable dry weather cycle for insecticides in EUC 1 and 2. This tasks involves the establishment of
dry accelerated cycles with specific regard to the loss of insecticides in EUC 1 and 2, prior to biological testing
according to EN 46 (Hylotrupes bajulus). The loss of insecticides will be related to loss under natural
conditions and the existing preconditioning procedure EN 73 (Task 1A);
b) establish the importance of hydrolysis and photo-degradation of insecticides and fungicides in EUC 1 and 2 in
service and related it to what happens in artificial procedures. (Sub-Task 1.1);
c) establish the fate of model compounds subjected to light, heat and moisture under conditions relevant to EUC
1 and 2. (Sub-task 1.1.1 Model compounds study);
d) develop "wet" artificial weathering cycles for fungicides and insecticides for EUC 3. The task involved the use
of wet artificial weathering cycles with respect of EUC 3 prior to both insect (EN 47) and fungal tests (EN 113)
with pressure treated wood. After weathering the appropriate biological tests will be performed and if
necessary chemical analysis of the active ingredients. The chemical changes and losses of fungicide will be
directly related to studies of the lap-joint field test (Task 2). Different partners will study different active
ingredients (Task 1(B));
e) establish the justification to apply the same approach to superficially treated wood in EUC 3 in an additional
national programme (Sub-task 1.2). Since superficial treatments are used in certain parts of Europe and
extremely sensitive to the various weather influences, the preservatives will be applied to the wood by
brushing or by means of a short-time dipping process. The fungicides and insecticides will be studied on wood
blocks treated superficially prior to decay testing and using the newly established weathering cycles. The
influence of the ageing on the active ingredients will be studied on the basis of the mass loss of the wood
samples (fungi) and the mortality of the insects, if necessary, on selective analysis of the active ingredients.
5.3 Deliverables
On planning the project CEN/TC 38 expected the following deliverables from Core Task 1:
a) data on the role of heat, light and moisture on the longevity of active ingredients in wood will be presented. A
statement on the suitability of the proposed EUC 2 artificial weathering cycle for simulating conditions and
losses in real exposures, such as the construction phase;
b) artificial weathering cycles (dry) suitable to EUC 1 and 2;
c) artificial weathering cycles with additional leaching and photochemical degradation for EUC 2 exposed during
the construction phase to the natural climate conditions;
d) artificial weathering cycles with leaching and photochemical degradation for EUC 3 (long term weather
exposition).
5.4 Material and methods
a) Model compounds (Sub-task 1.1):
The suitability of the EMPA standard cycle for artificial conditioning (Table 1) at recreating the conditions in EUC 2
and allowing degradation processes to occur has been assessed.
Wood preservative ingredients that are susceptible to losses by evaporation, hydrolysis and photolysis were
selected as the model compounds. Treated timber samples were exposed to light of known intensity and
wavelength, and to known relative humidity, temperature and hydrolysing conditions. The laboratory tests, which
simulated conditions in the EUC 2 artificial weathering cycle, were also compared with replicate samples that were
exposed for 2 months in a 'natural' weathering exposure.
Table 1 — EMPA Standard cycle for artificial conditioning EUC 2
QUV accelerated weathering apparatus, with spray option, manufactured by the
Apparatus
Q-Panel Company, Cleveland, Ohio, USA.
UV light installation UVA-340 (12 to 88) tubes (l » 340 nm)
Temperature of chamber 40 °C during light exposure
Deionised water, with an electrical conductivity of < 5 mS/cm (hydraulic pressure at
Wetting water
entering the QUV device:+ 0,3 MPa (3,0 bar))
Water flow rate 3 l/min
Cycle 15 min spraying (dark) and 30 min light (without spraying)
Duration of the
7 days » 2 months natural weathering
weathering test
In all experiments Scots pine sapwood (Pinus sylvestris) panels were treated with model compound containing
wood preservative formulations and the analytical zone was 0,0 mm to 0,5 mm from the surface. Full details of
these exposures are recorded in Technical Annex 2.
1) Photolysis
The potential for photolysis to occur in treated timber was monitored by the extent of conversion of tri-butyl tinoxide
(TnBTO) to di-butyl (DBTO) and mono-butyl (MBTO) tinoxide. Panels were treated with a 1 % TnBTO solution in
white spirit and exposed to accelerated weathering in QUV chambers. The zone 0,0 mm to 0,5 mm from the
surface were analysed for TnBTO and its breakdown products (DBTO and MBTO) using a polarographic method.
2) Hydrolysis
The potential for hydrolysis to occur in treated timber was monitored by the extent of conversion of trihexylene
glycol diborate (THGBB) to boric acid. To recreate the conditions of EUC 2 panels treated with a 5 % THGBB
solution in white spirit were exposed in alternating cold cabinets and conditioning rooms at 90 % r.h , to create
condensation. The analytical method includes extraction of the THGBB from the wood samples in hexane followed
by a thorough washing of the hexane with water to hydrolyse the glycol to boric acid, transferring it to the aqueous
layer. The aqueous layer was then analysed quantitatively for boron.
3) Evaporation
The potential for evaporative loss to occur in treated timber was monitored by the extent of loss of lindane during
exposure. Extensive research has been conducted on the loss of preservative active ingredients due to evaporative
loss and the connection with the actives vapour pressure. A review of the literature is presented in Technical
Annex 2. A summary of findings highlighted that evaporation of lindane, our chosen model compound, in dry and
wet conditions needed investigating. Panels treated with a 0,5 % lindane solution in white spirit were exposed in
two vacuum ovens set at 40 °C (the operating temperature in the EUC 2 weathering cycle), one at a relative
humidity of less than 60 %, and one at a relative humidity greater than 90 %. Panels treated with lindane were
exposed in both conditions for one week as well as being cold stored for reference material. The samples were
extracted by methanol reflux and analysed by gas chromatography.
4) Natural 'weathering trials'
Samples of treated timber prepared with TnBTO, trihexylene glycol diborate and lindane and were exposed inside
the window joinery tests facility at BRE to simulate a 2 month exposure during the construction phase. Conditions
are warm but variable (5 °C to 22 °C), moist (70 % r.h to 95 % r.h and weekly misting with de-ionised water) and
light (exposed at 45° behind south facing glass). These conditions would allow losses to occur. The information
from these 'natural' weathered panels has been compared with the model compound studies to assess the
suitability of the artificial weathering cycle at simulating losses during the construction phase.
b) Surface treated wood
The wood preservatives, ageing methods, organisms and biological tests used within the project are described in
the Technical annex of Core Task 1. The biological tests have been carried out according to EN standards and to
an institution method of P13.
With the extensive tests, carried out within the frame of Core Task 1, it has been shown that the concentrations of
active ingredients (a.i) in wood preservatives, determined at the beginning, were not chosen within the most
suitable range. Due to the long test periods of ageing procedures and biological tests, the concentrations of the
active ingredients could, however, not be changed in the course of the project, as the different ageing methods
would have been even less comparable. As a consequence, no draft of a method for artificial ageing according to
EUC 1 to 3 can be presented to CEN/TC 38.
5.5 Results and discussion
a) Model compounds (Sub-Task 1.1):
A comparison of losses in the simulated artificial weathering conditions and the 'natural' weathering conditions
appears in Table 2. This is a synthesis of the data that appears in Technical Annex 2.
Results indicate rapid losses of TnBTO and the appearance of the degradation products DBTO and MBTO within a
day of exposure to photolytic conditions. Rapid hydrolysis of glycol diborate under artificial weathering was
observed and significant losses of lindane due to evaporation occur during the 7 days exposure.
Table 2 — Summary of losses due to degradation processes
Losses in artificial
weathering Losses in 'natural'
Type of EMPA weathering
simulation in weathering test
Model compound
degradation cycle for EUC 2
laboratory
(1 week) (2 months)
Photolysis TnBTO 40 % conversion of 10 % conversion of suitable
TnBTO TnBTO
Hydrolysis Trihexylene glycol Total loss 50 % suitable (severe)
diborate (THGBB)
Evaporation Lindane 30 % 50 % probably suitable
b) Surface treated wood:
In general it is to be stated that natural weathering and also the different artificial ageing methods can have a
varying influence on the biocidal protection of the treated wood, depending on the active ingredient (a.i), the
formulation of the wood preservative (water - or solvent-based) and on the wood species.
The influence of the different ageing methods varies according to the wood species. In comparative tests with
insecticides on Pine and Spruce, the chosen a.i concentrations on Spruce allowed a better differentiation of the
ageing methods. That can be due to the lesser penetration of the a.i into the wood and, consequently, to a more
intensive ageing exposition.
EN 73: it is suitable for the artificial ageing of treated wood, used in practice under dry conditions (EUC 1) and not
exposed to weathering during the construction phase respectively protected by that time with a top-coat. If the a.i
degradation is not a consequence of evaporation only but also of hydrolysis and/or photochemical processes,
EN 73 cannot simulate the real conditions in EUC 1 and 2 (Figure 1).
Key
1 water based permethrin
2 solvent based permethrin
3 water based farox
x mg A.i. / kg wood
WW without weathering
NW2 Two months natural weathering
SG 7 7 days artificial weathering according to the EMPA-cycle
UV BRE Ageing 7 days under BRE condensation conditions
SN SN 198890: 14 days ageing by 70 °C / 50 % relative air humidity
Figure 1 — Influence of the ageing method on the insecticide degradation on surface treated pine wood
EN 84: it is suitable for simulation of the environmental conditions in EUC 3 in which the a.i can be leached by
water only. It is not suitable in situations in which the a.i are also degraded by light, hydrolysis and evaporation (see
situations in the field). A method for artificial weathering should include all these parameters.
The artificial weathering procedures of BAM or EMPA SG, tested within the project can be taken as a basis for the
further development of the method (Figure 2). In opposition to the BAM method, the EMPA SG method shows an
acceleration of the ageing around factor 2. Independently of the method to be chosen, the different test parameters
need to be optimized. The same weathering cycle can be used for both simulations, the construction phase
previous to the exposure in EUC 1 or 2 and the climatic conditions in EUC 3. The difference consists merely in the
number of weathering cycles, which should be carried out to simulate real conditions in the different EUC's. The
factor between the two ageing times respectively number of ageing cycles in EUC 2 and EUC 3 should amount to 3
at least.
Key
Treatment
*Brushing
** Steeping
BAM 7 BAM cycle, 7 days
SG 7 EMPA SG cycle, 7 days
Figure 2 — Relative influence of different ageing on the loss of efficacy of the fungicidal
wood preservation after treatment by brushing respectively steeping (criterion:
superficial attack by basidiomycetes; rating 1 to 6)
To evaluate the suitability of the chosen artificial weathering method in EUC 3, the weathering method with
6 months exposure time and a 45° inclination of the treated wood samples is appropriate, as described in EN 152-
1, subclause 7.2.1. A 90° inclination would prolong the required ageing time by a factor of approximately 2.
It should be taken into account that different types of active ingredients and also different wood preservative
formulations (e.g. water and solvent based preservatives) have to be used for the further development by
CEN/TC 38 of the EMPA SG or the BAM artificial weathering method. They show varying behaviour under different
weathering influences. In tests combining ageing and biological test it is important that the individual a.i are tested
in three concentrations at least, as for the individual ageing methods – especially in tests with fungi – mass losses
caused by fungi respectively mortality rates of insects can be reached only within a very close range of
concentration, which is required for the differentiation of the ageing methods.
As a rule, a statement with the biological test can only be made about "effective or ineffective" – without any closer
differentiation. With the chemical analysis the influence of the different ageing methods on the degradation of the
a.i can be studied continuously, from the initial active substance content up to the concentration of the detection
limit. In opposition to the biological test one a.i concentration respectively application rate is in general sufficient.
The data of the chemical analyses are available within shorter time than those of the biological tests. The
evaluation of the ageing methods based on chemical analyses implies that a validated analytical method is
available and that a sufficient number of random samples per test are analyzed. Subsequently it is possible to
analyze mixed samples of the different random samples.
If an artificial weathering method is developed by means of chemical analyses, it should be validated in the end
with a ringtest combined with a biological test, before it can be submitted to the final vote of the different countries
as a European Standard. Tests within the project have revealed that the data of the chemical analyses and those
of the biological tests do not always correspond.
5.6 Conclusions
a) Model compounds (Sub-task 1.1):
The results show that the EMPA artificial weathering cycle for European Use Class 2 reproduces the losses in a
'natural' EUC 2 exposure environment. The photolytic degradation of the model compound TnBTO in the
weathering cycle is greater than in two months 'natural' exposure as is the loss of the model compound THGBB
due to hydrolysis. The evaporative losses of lindane are comparable in both exposures, as the data in Technical
Annex 2 show.
Overall, the EMPA weathering cycle is concluded to be suitable for simulating the effects of two months exposure
of, for example roofing timbers, during the construction phase.
b) Surface treatment:
The aim of Core Task 1 to submit artificial ageing methods ready for standardization to CEN/TC 38 could not be
reached. But the methods tested in the project represent an excellent starting point for the further development.
Both the EMPA SG and the BAM cycle for surface treated wood can be taken as a starting point for EUC 1 and 2
with construction phase and EUC 3.
The development of the processes can be accelerated and cheapened if, at the evaluation, an increased number of
chemical analyses of the a.i are carried out in the place of the biological tests.
c) Pressure treated wood:
See special Progress Report to pressure treated wood in EUC 3 (Task 1B) from P5.
6 Core task 1 Part B: Weathering cycles (EUC 3), impregnation treatments
According to the test requirements of EN 599 for efficacy evaluation of wood preservatives two preconditioning
methods for basidiomycete testing are included. A evaporative ageing test according to EN 73 is intended to detect
decrease in efficacy when preservative test specimens are exposed to an air flow at 40 °C in a wind tunnel. The
leaching procedure according to EN 84 intends to prove sufficient leaching resistance of the preservative to be
used under conditions with permanent moisture impact as in use classes 3, 4 and 5 as mentioned in EN 335. Both
preconditioning methods are developed to cover the impact of specific physical phenomena: evaporation and
leaching.
Under outdoor circumstances the impact of weathering is more complex. This study envisaged therefore to
evaluate artificial ageing to provide in alternative preconditioning while acting in a similar way as natural
weathering. Three partners were involved in this sub-task P5 (RUG), P4 (BAM) and P3 (TNO). They all proposed
artificial weathering systems in an UVS apparatus (UV-cabinet either QUV from Q-Panel or UVCON from Atlas with
a spray option) or cycles for this purpose and compared them with the ageing cycle from EMPA as used in other
tasks. A summary of the most important parameters of artificial ageing cycles are given in Table 3. The EMPA-SG
(Sankt Gallen) cycle differs from the EMPA-Dü (Dübendorf) cycle as it uses primarily spraying over a longer time in
stead of condensation. All ageing systems used by the partners are detailed in Technical Annex A: UVS-RUG,
UVS-BAM, UVS-TNO and UVS-EMPA-SG. UVS-EMPA-Dü is listed for comparison while WOM-RUG is the same
ageing system but performed in a Weather-O-Meter (WOM) using Xenon light in stead of UV. The WOM system is
regarded as potentially better with correlating with natural weathering but the equipment and test costs are
considerably higher.
All partners used a common test set up and added some specific parameters. The common set up was based on
three preservatives: triazoles, TBTO and Cu-HDO. Pine sapwood blocks according to EN 113 having dimensions
15 mm by 25 mm by 50 mm were vacuum impregnated with diluted treating solutions to attain active ingredient
concentrations at low, sub-optimal, optimal and high level with regard to the expected toxicity levels. An example is
given in Table 4.
The EMPA-SG cycle was used alongside specific cycles for each institute while non-aged material and
preconditioned specimens according to EN73 (triazoles and TBTO) or EN 84 (triazoles and Cu-HDO) were
included for comparison. To a limited extent some specimens were also exposed under outdoor conditions. All
artificial weathering experiments were performed in UVS cabinets using UV light with 340 nm lamps and had a
water spray capacity of 3 l/ min, all specimens were fixed to an identical rack produced for this purpose.
Fungal testing according to EN 113 was carried out using one common fungus for each preservative: Poria
placenta for the triazole preservative and Coniophora puteana for both the TBTO and Cu-HDO preservatives. At
BAM (P4) both test fungi were used for all preservatives and additional fungal test were performed using as
second Coniophora strain and an Antrodia fungus. At RUG (P5) also Gloeophyllum trabeum was included.
Table 3 — Summary of most important parameters of artificial ageing cycles
Cycle Lamps Water flow Duration Cycle
UVS-EMPA-SG 15 min spray
30 min light
3 sub cycles
A: 15 min wet (1/3 spray) + 10 min light
21 days B: 30/60/120 min light,
UVS-BAM each + 1 min spray,
all + 120 min condensation
3 l/min C: 30/60/120 min light,
UVA each + 1 min spray, all + 3 x
340 nm (120 min light + 60 min dark)
2 sub-cycles of 1 week each
A: 24 h spray + 4 x
UVS-TNO (8 h light + 3 h spray + 1 h dark)
B: cyclic
102 min light + 18 min spray
UVS-RUG 2 sub-cycles of 1 week each
A: 23 h light + 1 h dark +
WOM-RUG Xenon 4 weeks 4 h spray + 2 h dry + 10 h spray + 2 h dry + 6 h dry
B: cyclic: continuous light and
102 min spray off + 18 min on
UVS-EMPA-Dü 24 h condensation,
then cycles of
UVA 3 l/min 21 days 5 h light + 1 h spray
UVS-TNO-2 340 nm 24 h spray,
then cycles of
14 h condensation + 8 h light + 1 h spray + 1 h
dark
Table 4 — Common set up of preservatives and solvents used
Preservatives Solvent Dilution (%) Retention a.i (kg/m³)
4,5 0,125
6,75 0,190
Triazole (0.45 % a.i)
Xylene
9,0 0,250
13,5 0,375
2,5 0,125
3,5 0,175
TBTO (1 % a.i)
Xylene
7,5 0,375
10,0 0,500
1,75 12,5
3,5 25,0
Cu-HDO conc. Water
5,25 37,5
7,0 50,0
Based on all information derived from the fungal test executed it can be concluded that ageing systems can be
ranked according to their impact from low to high:
1) for the triazole preservative:
EN 84
< EN 73
< UVS-EMPA-SG / UVS-RUG / WOM-RUG / Natural weathering / UVS-TNO
< UVS-TNO-2 / UVS-BAM
2) for the TBTO reference preservative:
UVS-BAM
< UVS-EMPA -SG
< UVS-RUG
< EN 73
3) for the Cu-HDO preservative:
EN 84
< UVS-TNO
< UVS-EMPA-SG / UVS-RUG
< UVS-BAM
An overall conclusion on the best suitable ageing system should be based on two criteria:
 mimic as much as possible the natural weathering results;
 as close as possible to expected impact of EN 84 on Cu-HDO and of EN73 on TBTO.
Based on both criteria the UVS-BAM cycle and the second UVS-TNO-2 are not as suitable as the other artificial
ageing systems. Relative to the importance of the TBTO reference the UVS-RUG gives a possibility to allo
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