EN 839-2014 pdf download.Wood preservatives – Determination of the protective effectiveness against wood destroying basidiomycetes -Application by surface treatment.
7.5 Number and distribution of test specimens The test specimens are divided into:
a) e treated test specimens:
— These are the treated test specimens subjected to attack by the wood destroying fungi. Use at least six test specimens for each combination of preservative, quantity to be applied, preservative concentration, test fungus and for each timber species.
— In case of dipping select at least 6 test specimens within a range of 10 % from the target retention. Supplementary samples shall be treated, in order to have a sufficient number of correctly treated specimens to put in test.
The treated test specimens are assessed by visual examination for decay of their surfaces and/or interior by the test fungi. If optional tests for colonisation of the test fungi are required as an additional method of assessment, this should be carried out on a parallel series of treated test specimens (Annex C).
b) c2 untreated test specimens:
— t’21 untreated control test specimens: these are untreated test specimens, equal in number to the treated test specimens and of the same wood species, which are placed one in each culture vessel together with a treated test specimen:
— e2. virulence control test specimens: these are untreated test specimens which are subjected to attack by the test fungi to monitor vigour. Use six of these for each combination of test fungus and timber species used in the test.
c) e3 treated check test specimens for calculation of the correction value:
These are test specimens treated in exactly the same way as the e1 test specimens. Use at least six test specimens for each combination of preservative, quantity to be applied and preservative concentration and of the same wood species. They are placed, after drying, conditioning and any appropriate ageing in uninoculated culture vessels, two in each vessel. Variations in mass of these test specimens make it possible to determine the correction factor (C) of the variations in mass of the treated test specimens e1 resulting from factors other than attack by the test fungi. At a given treating concentration. factor C is the mass fraction change of the e3 test specimens.
Mark each specimen so that it can be identified throughout the test.
8 Procedure
8.2.1 Preparation
Place the numbered test specimens to be treated (Cl and e3) in the oven at (103 ± 2) °C (5.3.2) and leave them there for 18 h to 24 h1. Cool to room temperature in a desiccator (5.3.3) and weigh to the nearest 0,01 g to determine the initial dry mass (in0). Place the test specimens in the conditioning chamber (5.3.4) until they need to be end-sealed (8.2.2).
8.2.2 End-sealing
Apply the end-sealing compound resistant to the penetration of the test wood preservative (5.2.4) to both end- grain surfaces of each test specimen to be treated fri and e3). Allow to dry in the conditioning chamber (5.3.4) for at least 24 h after the last application.
Since variation in end seal amount can create errors on mass loss careful operation in applying the end seal as evenly as possible is required. As quality control guideline a variation within a 10 % limit should be envisaged and additional absolute mass correction to all specimens could be useful.
8.2.3 Treatment with the test wood preservative
Treat the test specimens e1 and e3 on the unsealed longitudinal faces. If application is by brushing or by pipette, calculate the amount of test product required to treat each face, Apply the amount evenly to each face individually and weigh the test specimen before (in1) and after (ma) each application to the nearest 0.01 9. Allow to dry between applications. Calculate the uptake of wood preservative solution for each face of each test specimen (in2 – mi). Calculate the total uptake for each test specimen and express it in grams of wood preservative per square metre of treated surface,
NOTE If the balance has a tare facility, it is easier to tare the balance with the lest specimen on it, apply the test wood preservabve, and then record the uptake directly.
If application is by dipping, weigh each test specimen to the nearest 0,01 g (m1), dip for the required time then remove any excess l,quid with absorbent paper. Reweigh each test specimen immediately and record the mass after treatment (in2).
Calculate the uptake of wood preservative solution for each test specimen (m2 – in1) and express it in grams of wood preservative per square metre of treated surface.
8.2.4 Drying
Following treatment (8.2.3), place the treated test specimens on drying supports (5.3.5) in the conditioning
chamber (5.3.4). Invert the test specimens twice each week. Dry the test specimens until weighing at 24 h
intervals are within ± 0,01 9.
NOTE The length of the drying penod will vary with the nature of the test wood preservative.EN 839-2014 pdf download.