EN 152 Wood Preservatives - Determination of the Preservative Effectiveness of a Preservative Treatment Against Blue Stain on Wood in Service - Laboratory Method

The European standard EN 152 Wood preservatives - Determination of the protective efficacy of a protective treatment against blue stain in wood in service - Laboratory method describes a method suitable for testing preparations and systems intended to prevent the formation of blue stain fungi in wood in service. However, this method is not suitable for assessing the temporary preventive efficacy of stain preservatives in roundwood or freshly sawn wood. The method is not intended for determining the fungicidal properties of surface coatings applied to wood after a primer coat.

This European standard provides a method for determining the effectiveness of a preparation applied by brushing, spraying, spray tunnel, immersion or vacuum and pressure processes, which results in equivalent product retention in preventing the development of blue stain fungi in wood in service. It is also applicable where a primer is used in combination with a preservative system.

This method is valid for the following types of preparations or systems:

• Type A: Pigmented or unpigmented fungicidal preparations used in conjunction with unspecified varnishes or paint coatings
• Type B: Pigmented or unpigmented fungicidal preparations for use with specified varnishes or paint coatings.
• Type C: Pigmented or unpigmented fungicidal preparations used without any subsequent paint, varnish or other coating.

It is also possible to test the effectiveness in preventing blue stain in the service of a combined protective system consisting of the application of one preparation by a penetrating treatment technique followed by the application of a different preparation by a superficial treatment method.

For the purposes of this standard, the following terms and definitions apply:

• Representative sample refers to a sample having physical or chemical properties identical to the volumetric average properties of the total volume sampled.
• Supplier refers to the test sponsor (the person or company that provides the wood preservative sample to be tested)

The basic principles of the test method are to provide conditions for the infection of the treated surface and the cut surface behind the treated surface with blue spot fungi and to observe the development of infection on the treated surface.

In testing, a series of blocks of a given type of timber are treated with the preparation being tested on all surfaces except the end grain surfaces. The blocks are then sawn in the direction of the grain to produce two samples. The process varies according to the type of preparation and the characteristics of use:

• Type A preparations are tested using a standard test varnish designed for use with unspecified varnish or paint coatings, at an application rate appropriate to the preparation, or as otherwise specified by the supplier.
• Type B preparations are tested using a surface coating designed for use with the specified varnish or paint coatings, at an application rate appropriate to the preparation or strictly in accordance with the supplier's specification as otherwise specified by the supplier.
• Type C preparations are designed for use without subsequent varnish or paint coatings, tested using the application rate appropriate to the product or as otherwise specified by the supplier, but without subsequent coating application.
• Machined test specimens are subjected to preconditioning (natural or artificial abrasion).
• The corroded test samples are then exposed in the laboratory to a mixed culture of the two fungi that cause blue stain in service.

Preparations intended for use in use class 2 only may be preconditioned using the evaporative ageing method in EN 73 instead of the natural or artificial weathering procedures in this standard.

Among the numerous tests, measurements, analyses and evaluation studies that our organization has carried out for businesses in various sectors, our organization also provides testing services defined in the standard “EN 152 Wood preservatives - Determination of the protective effectiveness of a protective treatment against blue stain on wood in service - Laboratory method” with its trained and expert staff and advanced technological equipment.