EN 84 Durability of Wood and Wood-Based Products - Accelerated Ageing of Treated Wood Before Biological Tests - Infiltration Procedure

A European standard “EN 84 Durability of wood and wood-based products - Accelerated ageing of treated wood prior to biological testing - Infiltration procedure” describes a leaching method that can be applied to test samples of wood or wood-based products that are subsequently subjected to biological testing.

This method can be applied to:

• Preconditioning of test samples before subjecting them to biological testing
• Evaluation of loss of efficacy by comparing the performance in the biological test of treated test samples subjected to this procedure with others that have not undergone any leaching procedure.

This method can also be used to precondition untreated wood, modified wood and wood-based panel products, whether or not they have been preservative treated.

The principle of this method is based on the impregnation of samples prepared for biological tests against fungi or insects with water under vacuum using appropriate standard methods and then immersion in water for a certain period of time.

The water used in these tests complies with class 3696 as described in the standard “ISO 3 Water for analytical laboratory use - Specification and test methods”. This water is suitable for most laboratory wet chemistry work and for the preparation of reagent solutions. It should be produced, for example, by single distillation, deionization or reverse osmosis. Unless otherwise stated, it should be used for ordinary analytical work.

The equipment used in these tests includes:

• Conditioning chamber controlled at 20 degrees plus/minus 2 degrees and 65 percent plus/minus 5 percent relative humidity for conditioning test samples.
• Test vessels made of material that does not react with the preservative product being tested (especially vessels made of glass for organic solvent products or of plastic materials for products likely to attack glass). The capacity of the test vessels shall be such that they can contain the volume of water specified in this standard in addition to the test samples.
• Vacuum dryer with faucet attachment.
• Vacuum pump with pressure gauge installed and capable of maintaining a minimum pressure of 4 kPa.
• Machined blocks for ballasting test samples, weights made of material that does not react with water or the test vessel.

Test samples and their preparation are defined in the standards for the biological tests to which they are intended. The leaching procedure should be carried out after completion of the preparation of test samples for the test described in the relevant biological test standard. This includes any processing and subsequent conditioning processes where relevant.

The number of test samples should allow the relevant biological tests to be performed in accordance with the instructions in the relevant standards. In some tests, the leaching procedure may be applied to both control samples 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 leaching 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 change in the behavior of the reference species after leaching.

Leak tests are performed using two different methods:

• Impregnation with water: Test samples are placed in test containers. Test samples of different species, samples treated with different products or with different concentrations or loadings of the same product, wood samples modified using different treatments or of different sizes, or both test and control samples are not placed in the same container. They are balanced with weights to prevent them from floating. Sufficient water is poured into the test containers to cover the groups of test samples and to ensure that the test samples remain covered during impregnation. The test containers are placed in a vacuum dryer, a vacuum corresponding to a pressure of 4 kPa is created and maintained for at least 20 minutes before release. The test samples are left in the containers for at least 2 hours.
• In the water immersion method, each container is filled with fresh water in a ratio of approximately five volumes of water to one volume of wood (e.g. 50 ml of water per test sample of 25 mm × 15 mm × 100 mm). It is not necessary to continue ballasting the test samples after the impregnation procedure, as they will not float. This cannot be the case, for example, if test samples of wood-based panel products are being processed. The test samples are allowed to be immersed in water at the specified temperature for 14 days, and the water is changed nine times (the water is changed at the end of the first and second day of immersion and seven more times at intervals of at least one day and no more than three days in the remaining 12 days).

The test specimens are placed on one of their narrow edges on a non-absorbent backing material that will not react with the treated specimens, leaving a gap of at least 10 mm between each test specimen to allow free air flow around the test specimens. The test specimens are held for at least two weeks or until they reach constant mass, i.e. two successive weighings made 24 hours apart are the same.

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 84 Durability of wood and wood-based products - Accelerated aging of treated wood before biological tests - Infiltration procedure” with its trained and expert staff and advanced technological equipment.