Environmental influences such as rain, moisture, and fire affect the stability of OSB boards. In view of these challenges, the SMS group has applied its expertise in zinc coating of metals on wood materials in a test. The aim is to offer the construction and wood industry new solutions for optimized wood surfaces.
In this context, the SMS group has investigated the advantages of a zinc coating with its PERFECT spray® wire arc spraying system for OSB boards in terms of moisture and fire resistance and obtained promising test results. For a detailed overview of the test procedure, please refer to the corresponding application report.
Increased surface protection standards for wood building material
OSB boards, otherwise known as oriented strand boards, have an irreplaceable function in interior and exterior finishing, especially in the construction sector. The boards are highly resilient and can therefore be used in a variety of ways for cladding the exterior walls of buildings. Further, OSB boards can be combined with other materials and are suitable as a substrate for tiles and other floor coverings. Due to the basic material of wood, the building sector must overcome the challenges of moisture, rain, and fire resistance when using OSB boards. For example, traditional particleboard, such as OSB boards, must be resistant to moisture, particularly when it contacts the ground.
The test setup for the zinc coating of OSB boards with wire arc spraying
Zinc is a common surface coating used to protect metals against corrosion and/or to increase fire resistance. This raises the question of whether such effects also increase the surface resistance of wood products. The assumption is that these are only partially effective on wood, as the conventional corrosion that occurs with metals does not apply to wood.
In investigating the coated OSB board’s resistance to moisture and rain, coated samples were exposed to standing water in a 24-hour comparative test. The test samples were weighed and filled with water at regular intervals to measure whether water was entering the material.
To test the resistance to fire, three OSB boards with sprayed-on zinc coatings of different thicknesses were continuously flamed locally with a burner. In accordance with fire resistance class F30, the test was limited to 30 minutes.
Promising test results for higher surface protection of OSB boards
In the test procedure, increased resistance of the zinc-coated OSB boards was found compared to uncoated ones. In terms of resistance to standing water, it was determined that a zinc coating with low porosity can prevent or at least delay water entering the material. The effect is enhanced by applying additional sealants to increase longevity despite external moisture effects.
OSB boards with a thermally sprayed zinc layer also showed good results in terms of resistance time to flammability. In this test, a coating thickness of 100 µm was sufficient to protect the sample from further burning for 30 minutes.
Optimizing the surface protection of OSB boards with SMS group
Following the positive results, the coating specialists at SMS group are interested in further advancing the process with partners from the construction and wood industries, or in putting it to use under practical conditions. Thomas Hohnen, Head of Sales Coating Equipment, at SMS group: "We look forward to discussing this with the relevant experts and are happy to exchange ideas on which variants are suitable and which solutions we can tailor for our customers to meet their individual requirements with our PERFECT spray® wire arc spraying system."