Shaping the perfect ornamental tree

How Different Types of Preservative are Used to Treat Pine

Timber is a widely accepted product used throughout the building industry. It's environmentally friendly and is harvested from sustainably-managed forests. However, in its natural state once harvested it will be subject to degradation. This is why any timber used in outdoor environments is treated to survive attack from weathering, insects or fungal infestation. What types of treatment are used and for what final applications?

Three Categories of Preservative

Treated pine is injected with special chemical solutions to guard against insects and fungi. The process used injects these preservatives far into the wood, giving the product long-term resistance. There are three different categories of preservative used in the industry – water born, oil borne, and light organic solvent preservatives.

Water Borne

The most commonly used preservatives are waterborne, due to their relatively low cost and good availability. These include Alkaline Copper Quarternary H3, Chromated Copper Arsenate H3-6 and MicroPro, H3–4.

  • Alkaline Copper Quarternary is a composite made from quarternary ammonium and copper. The treated timber has a light greenish appearance and will change in colour over time to brown and then grey. The timber, which can be used for decking, playground equipment or most outside furniture, can be stained or painted with a variety of different colours.
  • Chromated Copper is one of the oldest solutions in the marketplace and is made of copper as a fungicide, arsenic as an insecticide and chromium as a binding agent. This type of treated pine wood is largely maintenance free, very cost-effective and is often seen in landscaping, bridges, outdoor decks, carports and fencing projects.
  • The Micropro technology is in widespread use in the USA, but still represents a new approach in Australia. It is used in very concentrated formats and results in the creation of a much smaller amount of copper as compared to the other processes. This wood has a more natural timber appearance and is very receptive to staining and painting. It is commonly seen in playgrounds, public parks, boardwalks, decking, and pergolas.

Oil Borne

Oil borne preservatives are far less common. They include a mixture of creosote and sometimes fuel oil and the preservative is administered without solvents. Specifically, this approach is used to treat wood being used for railway sleepers.

Light Organic

Light organic solvent preservatives contain fungicides designed for protection against decay and insecticides specifically designed to control termites. It is applied using a vacuum pressure process. More specifically, the process used to inject the solution causes no swelling of the wood, and the timber maintains its aesthetic shape, size and strength. This type of treated wood is particularly good for structures in areas prone to termite outbreaks.

Learn more by talking to professionals such as Australian Treated Pine.