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Designed to give a weathered look without the wait. SiOO X is a wood treatment product, originating in Sweden, that uses a patented technology, to accelerate the weathered look of timber and provide a uniform finish.


SiOO X Mid Grey
Surface Finish – Structured


SiOO X Mid Grey
Surface Finish – Sawn Face


SiOO X Light Grey
Surface Finish – Planed


SiOO X Light Grey
Surface Finish – Sawn Face


SiOO X Clear
Surface Finish – Planed


SiOO X Clear
Surface Finish – Sawn Face

What is SiOO X?

Consisting of a unique combination of silicon and potassium – two natural substances found all around us and which, together, create a natural shield similar to nature’s own wood protection. SiOO X Wood Protection is inspired by how nature protects itself using silicon.

Trees and plants absorb silicic acid from the soil, which dissolves in water and is then transported in trunks and stalks, precipitating out in the organisms and making them stronger.

This is a treatment which uses a patented two-part system to give timber an attractive silver-grey patina. SiOO X can be used for a wide range of applications such as decking, cladding, boat docks and boat decks. It’s very durable and can be enjoyed for years to come.

The SiOO X Story

In his book “Wood Modification”, Callum Hill refers to the enormous potential in the new industry that has emerged from the development of wood modification technologies. Read the book here:

How does SiOO X work?

SiOO X is a two-part system which uses silicon technology to protect a timber substrate. SiOO X Wood Protector (Step 1) is applied twice, and contains potassium silicate, which can easily penetrate the timber. It opens up the surface structure of the timber and forms a barrier of silica crystals at the wood cells which are bonded to the timber.

SiOO X Surface Protector (Step 2) is then applied, and this envelops the system, binding with the SiOO X Wood Protector to form a barrier to prevent water penetration. It also works as an open system which allows for vapour diffusion, allowing the timber to breathe and react to the natural environment.

The two products work in unison to toughen the surface of the timber and effectively protect the timber from insects and rot. Once the SiOO X coated timber is fitted, SiOO X will immediately begin to react with carbon dioxide and moisture in the air. Over the next three to four months, you will see your timber weather at a uniform rate to an even and consistent finish.

SiOO X Colours

The original SiOO:X (Clear) can take between three to four months to begin developing a silver / grey appearance.  The rate of weathering depends on factors such as elevation and exposure.  For projects requiring a more immediate weathered effect, SiOO:X Light Grey and Mid Grey have been developed.  Light Grey SiOO:X gives an elegant silver/grey appearance while SiOO:X Mid Grey gives a deep grey finish.

The Benefits of Factory Finishing

The operation of our vacuum coating machine means we achieve a flawless and consistent finish. Factory finishing offers a range of benefits to end users. Primarily , a reduction in preparation and clean up time as timber arrives fully coated, ready to install.

Timber is coated in our purpose-built factory, which is temperature controlled, meaning the weather doesn’t affect the application of coatings, and coating can be carried out year-round.

All the timber we coat is sanded as standard using our in-line sanding machine prior to it being coated. This means each length of timber has been processed in exactly the same way from start to finish.

SiOO X can also be applied to sawn and structured boards dependant on the customer’s design criteria. Boards are coated on all four sides as a 3-coat system in accordance with SiOO X approved applicator criteria. This seals the timber all the way around, whereas when applied on-site, only the face is coated.


SiOO X Wood Protection products are water-based and made from non-toxic, natural ingredients which are biocide and emission free.


Wood is a natural material and, even when treated with a wood protection or a preservative, it can be impacted by dirt and atmospheric fallout including fungal spore. Urban environments are particularly prone, but rural environments are not immune as agricultural pollutants and airborne particles can be carried over considerable distances. Dirt and pollution can lead to the formation of algae and fungal growth.

Although the SiOO X treatment provides protective resistance to the penetration of algae and fungi, in humid climates such as in the UK and Ireland, they can, in some locations, take hold on the surface and have a negative aesthetic effect. The key is to understand that timber surfaces, no matter how they are treated, need to be cared for and maintained.

Early removal of accumulating dirt and any early-stage algae or fungal spore, through a regular care and maintenance programme, will lead to a sustained beautiful appearance. The majority of projects see no impact – it is a matter of particular environments. For more information or support with maintenance please contact us.


What are the most important factors for achieving long project life?

Good design detailing is crucial; for-instance with cladding avoiding ground contact, achieving a design which sheds water at eaves level and ensures adequate airflow behind the cladding and orientating the cladding vertically rather than horizontally as this allows water to dissipate more effectively. 

For decking ensure positive falls to allow water to shed off the surface, avoid ground contact and allow for good airflow around the supporting structure and the deck itself. 

The selection of good quality, high grade, durable timbers will also assist in maximising the life of your SiOO X coated product. 

Good preparation of the timber surface is vital, sawn surfaces give the best penetration of SiOO X, planed boards are to be sanded correctly prior to application and factory application is always the preferred method of application. 

In service maintenance is a factor that should be built into your design, planning how maintenance will be carried out at the design stage can save large amounts of time and money later down the line when service maintenance is required. SiOO X treated surfaces need to be kept clean by removing any dirt and surface fungi that forms at an early stage.

What do I do if there is damage to the timber?

For light surface damage such as a scratch apply the SiOO X Premium Surface Protection locally. Where the integrity of the surface has been breached apply both the SiOO X Premium Wood and the SiOO X Premium Surface Protector locally. The surface will evenly grey again after a period of time.

The wood surface is really nice but it grows a little green in the corners where there is shade. On the cladding, there are some little black spots. How do I remove them and why does this occur?

SiOO X Wood Protection forms a protective and dirt-repellent layer in the wood surface. When it gets wet and dirt washes off the surface, a little green or black algae can grow on the surface. Black dots are usually dirt which can be washed off. There is usually much less of this on SiOO X treated timber. The wood is protected from algae penetration but it should be cleaned off periodically. It should also be understood that green and black algae can grow on almost anything, even metal and stone, look at road signs on a country lane near trees for example. When you maintain your SiOO X treated timber the algae very easily washes off the surface. Avoid using a power wash, strong cleaning agents or stiff bristle brushes as this can remove the SiOO X treatment and therefore require re-application.

Why is the surface speckled and mottled after SiOO X is applied?

SiOO X requires being exposed to rain and moisture to activate the silicon technology. 

The silica networks which forms are what makes the surface a beautiful velvety grey appearance over time. The activation takes place over a period of around 4-8 weeks depending on the weather and other factors such as elevations etc. During this process any surface speckling will disappear.

How do I apply SiOO X?

On new projects the best option is to have your timber factory treated with SiOO X. Factory application has numerous benefits over on site application and is always the preferred method of application by SiOO X. Factory application by SiOO X approved coaters ensures excellent quality control and these applicators are audited annually.

Want to discuss your project with one of our Timber Coating Experts?

We provide every customer with the best possible solution to achieve the desired finish for your project.