Why is timber preserved?

We sell, amongst other things, impregnated spruce and pine garden timber. In other words, we preserve the spruce and pine timber. We do this because spruce and pine are naturally not very durable and the timber will start to rot after a few years without treatment. In addition to spruce and pine, we also sell Douglas fir and hardwood. These types of timber are naturally more durable and we therefore sell them untreated.

How does the preservation process work?

The preservation of spruce and pine timber begins with the (artificial) re-drying of the timber to a moisture content of around 20%. The timber is then placed in so-called vacuum-pressure impregnation vessels to add the impregnating fluid. This fluid is forced into the timber under high pressure, ensuring that the timber is subsequently protected for longer against natural degradation caused by fungi, insects and bacteria.

Is treated timber dangerous?

The answer is no. We treat our timber in accordance with the strict requirements of the KOMO Institute. KOMO is an independent institute that has carried out numerous studies to assess the impact of treated timber on people and the environment. The results have shown that treatment under the KOMO standard is not harmful to people or the environment. The chemicals we use are harmless to humans.

So, can preservative-treated timber be used and processed without any issues?

Yes. Various studies show that preservative-treated timber bearing the KOMO quality mark can be used without any issues for garden applications, such as play equipment, sandpits, vegetable and ornamental gardens, fences, compost bins, and so on. This is also evident from the fact that KOMO-certified treated timber can simply be disposed of with untreated timber at local waste collection points. When handling impregnated garden timber, you do not need to take any additional protective measures beyond those required for handling untreated timber.

If wood is preserved, does it last much longer?

Basically, it can be said that preserved wood lasts approximately five times longer than untreated wood. For spruce and pine, it can be said that after treatment they have an average lifespan of five to ten years. This does, however, depend on external factors such as the use of the correct fasteners (e.g. stainless steel fasteners), any subsequent treatments, the climate, etc. In addition, factors such as the proportion of sapwood also play a role. Sapwood is the outermost core of the wood; the so-called most recently grown part. This part is naturally less durable. If a type of wood has a high proportion of sapwood, it will be less durable.

So I don’t need to maintain treated wood?

As a rule of thumb, treated wood is low-maintenance. Once the wood has been treated, it no longer needs to be re-treated against damage caused by fungi, insects and bacteria. Please note: all types of wood (treated and untreated) remain susceptible to ultraviolet radiation. All types of wood will discolour (grey) over time under the influence of sunlight. This can be prevented by treating the wood with various colour-retaining finishes, such as stain and paint.

What is the aim of the staining process?

Some of our timber is anthracite-stained. The aim of the staining process is to achieve an opaque anthracite finish. Anthracite-stained products are not the same as black-sprayed products.

How exactly does the dipping process work?

The timber is immersed three times for 10 minutes in liquids that are circulated in a large dipping tank. The dip tank contains a mixture of ingredients, also known as additives. The dip liquid leaves its pigments, along with a number of other additives, in and on the wood. The pigments in the liquid give the wood its anthracite colour. The wood is dipped three times to ensure optimal adhesion of the anthracite pigments.

What colour does the wood take on after dipping?

Dipping is not a process that extends the lifespan of the wood; for that, the wood must be impregnated. For this reason, we first impregnate the wood to make it durable. We then dip the wood to achieve the attractive anthracite colour. The colour should be regarded as a base coat. After all, wood is not a ‘closed’ system; it breathes and reacts to weather conditions. Furthermore, knots, resin or other imperfections in the wood may turn whitish after dipping. Wood is a natural product and we cannot prevent this.

Staining

We advise consumers to stain pressure-treated timber with a coloured stain for outdoor use, which is available at DIY stores. Our advice is to stain the product within two years of installation, and to repeat this at least once every two years. This is to preserve the colour of the pressure-treated product as much as possible, protect the wood from the elements and extend its lifespan. The colour of the stain should be chosen by eye. The frequency of staining depends on the product’s location in the garden; for example, in full sun, in the shade or constantly exposed to rain.

RAL colours

When staining our pressure-treated garden timber products, the wood grain of the product remains visible. For this reason, and those mentioned above, we cannot specify a match between a RAL colour and our pressure-treated garden timber products.

Striping caused by stacking battens

Our garden timber products are treated as a complete batch. It may happen that a small section of the timber is visible where a batten is positioned, as the treatment solution could not reach that area completely. Consumers can remedy this with an outdoor wood stain. For the best result, it is best to apply the stain to the entire product.