LOSP Treated Pine
The other main form of timber treatment is known as LOSP or Light Organic Solvent Preservative. LOSP is a treatment that is usually a white spirit based solvent which contains copper naphthenates and synthetic pyrethroids as well as other chemicals to provide protection from insects and decay.
LOSP treated pine is usually machined to the required lengths and shapes before the treatment is applied. As a result of this less pressure is used in the treatment process and a little less penetration of solution is achieved. This does not affect the longevity of the timber, however it means that LOSP timber must not go in ground and if the timber is cut the cut ends must be resealed with a suitable sealant.
LOSP timber is frequently coated with a protective oil based primer which is usually pink. This primer is applied to stabilise and protect timber during storage and installation, not as a paint primer. As a result it is recommended that LOSP primed timber be sanded down to remove the primer before painting.
Unprimed LOSP timber is natural in its appearance as the solution used is clear and hence causes no discolouration of the timber. Like CCA the timber will weather and discolour if not stained or painted.
LOSP treated timber is occasionally treated with an oil based protective primer. This is called a Pink Primed (as the primer is usually pink) and it is always applied on kiln dried DAR finished LOSP. The Primer is intended as a protective coating only and should be sanded down before painting of the timber.
Alternative treatments
A few other treatments are currently available, they are both water based solutions and are quite similar to CCA in their potential uses. They are called ACQ and Tanalith E (or copper Azole)
ACQ or Alkaline Copper Quartenary is a relatively new treatment which is a water based solution which uses Copper to protect against rot and fungal attack and Ammonium Quartenary as a pesticide. ACQ treated timber possesses most of the same qualities as CCA timber in that it can be used in inground applications.
Tanalith E or Copper Azole treatment is another new water borne solution which again uses Copper as a fungicide and Azole as a pesticide, it too can be used in inground applications and has most of the same properties as CCA treated timber.
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