The objective of this technology was to find a way to protect the wood without chemicals and regardless of species, while improving its dimensional stability and its durability.

The solution did not come from new technologies or from biotechnology, but came from our ancestors, grandparents and prehistoric men, who subjected the tips of their lances to a flame to harden them and to get better durability. Our grandparents exposed their fence posts to a flame before planting them in the earth. They had observed that by doing so, the wood resisted much better to rotting at the interface zone between the ground and the air where wood rotting by mould is more concentrated.

This empirical approach of improving the wood had to be reproduced by a modern industrial process.

However, since the 1940's, several persons had tried to solve this problem. Unfortunately, the technology then did not allow to achieve an industrial production scale process. Since a few years, laboratory research was carried out with ovens using various temperature increase rates.

The advent of computers allowed us to complete this phase and we are now able to offer industrial heat treatment equipment for wood since a few years.

The Perdure technology consists in subjecting the wood to high temperature by a unique pyrolysis process under controlled atmosphere. The wood is heated to the core to over 200°C and no chemicals are applied. This process strengthens the molecular bonds of the wood and improves the natural physical-mechanical properties. The treatment creates the new Perdure building material that is naturally superior to wood.

The Perdure technology does not produce any atmospheric emissions. It only generates a very limited volume of liquid residues.

The treatment cycle consists of several phases:

• elimination of free water;
• elimination of bound water;
• actual heat treatment.

The elimination of free water is the easiest phase. The free water is lodged in the wood’s channels that move the elaborate sap and it is easy to remove.

Eliminating the bound water is more difficult because it is contained in the wood cells and must cross the cell walls before release.

However, these two operations are more or less lengthy depending on the percentage of initial humidity. For example, wood with 12 % humidity will have a relatively short water elimination phase, while freshly cut wood will require much longer time.

The third phase, the actual treatment, consists of modifying the macromolecular structure of the wood. This modification is achieved only by subjecting the wood to high temperature whereby alcohols, tars and resins migrate from the cells to the walls of the wood. These various products then form a protective layer that stops or slows down rotting when wood is exposed.

Perdure wood has very good dimensional stability. It has a relative humidity of around 0 % to 1 % at the end of the treatment that stabilizes at around 2.9 % to 3.5 % when left outside. Swelling and shrinkage are low. The coefficients of heat and acoustic insulation remain stable, regardless of the ambient humidity.

Biological characteristics

Lignin eating microorganisms (mushrooms in particular) need a certain humidity level to develop. Since Perdure wood has poor water retention, it is no longer a preferred medium for microbial action. Tests carried out at Forintek (research institute on wood products in Canada) and at Laboratoire d’Études et de Rercherches sur le Matériau Bois at Université de Nancy I, demonstrated the durability of Perdure wood by its resistance to cubical and fibrous rot attack. While mushrooms degrade untreated wood by 30 % to 70 % on average, they cannot degrade Perdure wood significantly. This wood may then be considered as exterior, non-sheltered and above ground grade.

The static bending strength of Perdure wood was measured by Forintek and revealed that it was not significantly lowered.

The National Testing Laboratory demonstrated that Perdure spruce strip cladding has a fire resistance of one (1) hour like untreated spruce.

Perdure wood can be manufactured and marketed right after thermal treatment, thereby avoiding numerous stocking and management problems.

Perdure wood may be planed like traditional wood and no additional abrasion was detected on the tools. However, given the hardness of the surface, it is sometimes necessary to adjust the cutting speed. A good vacuum system is recommended since the dust is very fine.

Wooden profiles are easy to nail, screw and staple, thereby allowing multiple uses.

• Jack (grey) pine: patios, may replace red cedar
• White spruce: desks, flooring
• White birch: furniture, flooring