EN 73 Durability of Wood and Wood-Based Products - Accelerated Ageing of Treated Wood Before Biological Testing - Evaporative Ageing Procedure

The European standard "EN 73 Durability of wood and wood-based products - Accelerated ageing of treated wood prior to biological testing - Evaporative ageing procedure" describes an evaporative ageing procedure that can be applied to test samples of wood and wood-based products that are subsequently subjected to biological testing. The method can also be used for preconditioning untreated wood, modified wood and wood-based panel products, whether or not they have undergone preservative treatment.

In principle, test samples are prepared for biological testing against fungi or insects using appropriate standard methods. The test samples are exposed to a dust-free air flow at a defined speed and temperature for a defined period of time.

The equipment used in these tests includes:

• A wind tunnel equipped with compartments and air heating and distribution devices: The air must be dust-free and free from contamination by chemical products that could affect the results of biological tests. The heating and distribution devices must be such that the temperature and air velocity are maintained constant and uniform in each compartment. The air exiting the tunnel must be removed so that it cannot re-enter the tunnel.
• A device that controls temperature within defined limits specified in this standard and measures and records air temperature within defined limits.
• An anemometer that can measure air speed to 1 plus/minus 0,3 m/s.

The test samples and their preparation are defined in the standards relevant to the biological tests to which they are intended. The evaporative ageing procedure should be carried out no later than 3 months after the completion of the preparation of the test samples for the test described in the relevant biological test standard. This includes any processing and subsequent conditioning periods where relevant. An alternative period may be used if specified by the product supplier. This should be stated in the test report. Before testing, the samples may be stored at 20 degrees plus/minus 2 degrees and 65 percent plus/minus 5 percent relative humidity. Any deviation from this should be stated in the biological report.

The number of test samples should allow the relevant biological tests to be performed in accordance with the instructions in the relevant standards. It should be borne in mind that in some tests the evaporative ageing procedure will be applied to both control and test samples.

Control samples may be of the following types, if required by the relevant test standard:

• Control test samples that will not be subject to attack by biological agents after the evaporative ageing procedure. These serve as controls for mass changes in tests where this factor is taken into account.
• Untreated control or reference species samples subjected to biological agents to check for any changes in the behavior of the reference species after evaporative ageing.

When performing the test, test specimens are placed in compartments on grids made of metal or other inert material that can be decontaminated, and placed with one face down on the bottom, with no other surfaces less than 10 mm from the side compartments. Faces parallel to the grain of the wood should be parallel to the general direction of the air flow and should be at least 10 mm away from corresponding surfaces of adjacent test specimens. Test specimens of different species, specimens treated with different products or with different concentrations or loadings of the same product, wood specimens modified using different treatments or to different sizes, or both test and control specimens should not be placed in the same compartment:

Test specimens whose surfaces perpendicular to the wood grain have been sealed before treatment are arranged as above. However, the sealed surfaces may be brought closer together. Test specimens with only one treated surface are placed on the opposite side of the treated one.

During startup and setup of the device, with the test samples in position, an air current is created that enters the chambers at a speed of 1 plus/minus 0,3 m/s and is controlled at a temperature of 40 degrees plus/minus 2 degrees.

In the arrangement and under the conditions specified in this standard, test specimens shall be stored for two weeks (14 days). In order to obtain uniform evaporation from all treated surfaces of a test specimen, test specimens shall be rotated 14 degrees about their minor horizontal axis every two weeks (180 days). Test specimens with only one treated surface shall be rotated 14 degrees about their vertical axis every two weeks (180 days).

If there is more than one test sample in a chamber, the position of the samples within this chamber is changed at the same time as rotating the test samples. The method depends on the number of test samples included and the duration of the procedure.

Among the numerous tests, measurements, analyses and evaluation studies that our organization has carried out for businesses in various sectors, it also provides testing services defined in the standard “EN 73 Durability of wood and wood-based products - Accelerated aging of treated wood before biological testing - Evaporative aging procedure” with its trained and expert staff and advanced technological equipment.