LOSP Treatment

Nathan Taplin
Posted in Timber - Jun 01, 2016

LOSP, or Light Organic Solvent Preservative is a form of treatment that offers similar resistance to weathering and termites as CCA treated pine, using a lower impact preservative.

Most of the LOSP timber is easily identifiable as it is coated with a coloured primer and is machined to an exceptionally smooth and flawless finish. Our LOSP timber is all plantation grown and is both environmentally friendly and 100% sustainable.

The process for making such precisely machined timbers is complicated and involves removing any natural defects from the timber. To do this, the lengths of timber require cutting, so once the defects have been removed, lengths of timber are then finger joined and glued back together to form a perfectly straight defect free product. This has the benefit of ensuring that there will be no leeching of sap or resin through the primer or paint for the life of the product, and that the boards are far less likely to bow as they are generally made up of a few shorter lengths.

The glue and finger joining on these boards has approval for use up to Durability Class 3 standards, which allow for its use outdoors and uncovered. Further to this, the primer used on LOSP timber acts as a UV resistant layer and a great undercoat, so no preparation is needed for painting and a top coat can be immediately applied for an excellent finish.

LOSP timber is used in a lot of outdoor applications; it is use primarily in Pergolas as its smooth finish make for a great clean looking structure. As it is slightly more expensive than CCA treated pine we would recommend the use of CCA in non-appearance situations such as for the sub floor of a decking. LOSP is also suitable for high contact use as per the APVMA guidelines as it’s preservative has no heavy metals and won’t leech.

When working with LOSP timber it’s recommended that you spray cut ends with a suitable sealant, to preserve the integrity of the primer and make sure that there is no uneven uptake of moisture into the timber. Despite this LOSP is treated to H3 levels and the preservative contains waxes and resins that slow the uptake of any moisture, so this is largely precautionary advice.