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Pre-treatment preservatives and processes

Copper-organic (water-based)

Use class suitability: UC1, 2, 3 and 4.  
Application process:  high-pressure

Suitable for situations were risk of bio-deterioration is high e.g. ground and fresh water contact components, fencing, decking, timber embedded in masonry.  Treated wood has no smell and does not discolour or taint adjacent materials.  Treatment imparts a greenish colour to the timber making it easy to identify.  A dye can be added to impart a brown colour.  Treatment will cause timber to swell, raise the grain and may cause some distortion.

Organic (water-based)

Use class suitability: UC1, 2 and 3 (uncoated and coated)
Application process: high-pressure

Ideal for external, out of ground contact landscape and cladding timbers.Treatments is clear and does not colour the timber. A colorant can be added to aid indentification. Treatment will cause timber to swell, raise the grain and may cause some distortion.

Microemulsions (water-based)

Use class suitability: UC1, 2 and 3 (coated).
Application process: low pressure (double vacuum)

Ideally suited for internal construction timbers. Although water based, the treatment has little effect on dimensions of timber but may raise the grain. Can be used on joinery items where surface appearance is not of prime importance.

Organic solvent (also known as light organic solvent products LOSP)

Use class suitability: UC1, 2 and 3C (coated)

Application process: low pressure

Organic solvent preservatives do not change the dimensions of timber or raise its grain; they do not change the colour of the timber (unless tinted for the purposes of identification), making them particularly suitable for joinery products.

Boron compounds

Use class suitability: UC1, 2 and 3C (coated).
Application process: high-pressure processes to seasoned timber alternatively, by diffusion processes to timber before seasoning.

Boron treatments do not change the colour of the timber. Treatment may raise the grain and, if applied using a high pressure process, may cause the timber to swell.

Creosote

Use class suitability: UC3u (uncoated), 4 and 5
Application process: high pressure

Creosote is suitable for extended service life components to be used externally, above and below ground and in water contact e.g. railway sleepers, utility poles, piles, fencing, landscaping and earth retaining walls

Treatment with creosote reduces moisture movement in timber. It can be difficult to paint over and can stain absorbent materials with which it comes into contact.

The use of creosote is restricted to products produced using an industrial application process. The use of products treated with creosote is also restricted to specific applications.

For more detailed information about creosote click here.

Applications Gallery

Treated Wood Applications

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  • Does wood need preservation treatment?
  • The benefits of pre-treatment
  • British Standards Use Classes
  • Risk and consequences of failure
  • Preservative types and processes
  • How to specify
  • Wood preservation on-line learning
  • Re-use, recycling, disposal
Wood Preservation
Check out our Wood Preservation pages for useful information on the application and treatment of timber.
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