Fences produced from autoclaved wood: combining robustness with beauty
Autoclaved wood fences are incredibly long-lasting. They enjoy long-term protection against biological attacks including insects and fungus. According to the treatment applied, these fences can have a life expectancy of up to 20 years.
Why choose autoclaved wood fencing?
Wood needs to be protected. This is particularly the case if it is constantly exposed to bad weather or in permanent contact with the ground, or even with water and frost. Local tree varieties such as spruce are particularly subject to biological attack and sensitive to weather conditions. Treating a fence in an autoclave protects it over the long term.
Each wood variety is comprised of a hard part and a much softer sapwood part. This second part can be impregnated. The percentage of sapwood varies according to the variety. This is why some types of wood can be impregnated more deeply than others.
What is autoclaving?
The structure of the wood can be likened to a sponge. It’s comprised of cells, namely cavities and walls. By impregnating the wood, you’re treating the wall with a protective product preventing fungus and destructive insects from causing harm.
Unlike dipping, the use of autoclaving makes it possible to act deeply inside the wood by treating it in a vacuum and under pressure. For salt impregnation, the wood is placed inside the machine, which creates a vacuum. This makes it possible to extract the surface humidity and to open up the pores, rather like a sponge crumpled up in a person's hand. The wood treatment product is then injected into the autoclave and pressurisation begins. In doing so, the product penetrates the sapwood under high pressure. The wood recovers its usual form, just as the sponge would when you release it. A final phase, also performed in a vacuum, makes it possible to avoid any surface stains, to start the drying process and to remove any surplus wood treatment products.
For a creosote treatment, the tank and the wood are both heated beforehand to prepare the wood to the high temperature and to open its pores. The wood treatment product is then inserted into the tank which is pre-pressurised. The goal is to get the wood used to the product. The tank is pressurised, and the product penetrates into the wood’s fibres. At the end of this pressurised phase, a vacuum is once again applied to remove any excess creosote and to ensure the wood is not "greasy" when it comes out of the autoclave. Once the treatment process is finished, the excess creosote is pumped from the autoclave into the reservoir and the wood can drain off.
After a period of 24 hours for the product to "fix", the wood enjoys long-term protection against insects, fungus and rot even if it is in constant contact with the ground or with water.
How can the effectiveness of an autoclave treatment be further improved?
Not all autoclave salt treatments are the same. Different factors can directly influence the quality and effectiveness of the treatment:
- The concentration of the product used for impregnation: the concentration of the product must match that recommended by the manufacturer. A concentration just a few tenths of a percent below the required dose can significantly affect the effectiveness of the treatment and consequently can drastically reduce the life expectancy of the wood.
- The treatment time: a treatment performed too quickly will not allow the product to penetrate to the required depth, which also affects the wood’s life expectancy.
- The drying of the wood: when the wood is dry, the creosote adheres better to the cell walls comprising the wood. Drying therefore significantly improves the treatment’s effectiveness.
Some companies are holders of a technical approval. Peter Müller has such an approval for salt impregnation. This confirms that the wood has been impregnated in accordance with trade practices and that the company complies with the usage instructions issued by inspection bodies such as Wood.be and SECO. The company Peter Müller is approved for salt impregnation.
What are the available treatments?
- Salt offers the perfect solution when users are regularly in contact with the wood, for example show rings or paddocks. The treatment gives the treated wood a pale green colour. Being chrome-free, the product will not harm the environment.
- Coloured salt is obtained by adding pigments to the saline solution. These give the treated wood a brown tint. This treatment offers all the same benefits as conventional salt impregnation.
- Creosote offers longer-lasting protection for the wood than salt or coloured salt. However, it is recommended that direct contact with the skin be avoided. These days, companies like Peter Müller use type C creosote, which has a less pronounced smell and which is more environmentally friendly than other types of creosote.
- Partial impregnation through dipping makes it possible to treat the most critical part of a post, its base, with creosote. The rest of the post remains untreated or is treated with salt (coloured or otherwise). This additional protection considerably improves the post’s life expectancy.
You can trust Peter Müller, a specialist in autoclaved wooden fencing in Belgium
The company Peter Müller is a specialist in wooden fencing in Belgium. It has its own impregnation equipment. Being independent of any outside supplier, it offers short lead times and a high degree of flexibility.
Its DURAfence equestrian fences are produced on a bespoke basis according to the specific needs of each client. They are manufactured on-demand in Belgium. Assembly is performed by a team of qualified workers. Perfectly adjusted, they are therefore highly resistant to the weather and meet even the most demanding requirements.