Weathering to silver-gray

Weathering to silver-grAy

Once the SiOO:X impregnation system has been applied, when exposed to moisture the mineral silicate in the impregnated timber substrate begins to cure by reacting with atmospheric carbon. During this curing reaction a network of silica crystals starts to be formed and this process continues for up to three years. The result is that the timber surface is toughened and an even accelerated weathering takes place. This is a permanent change.

The cure rate is timber species and temperature dependent and will proceed very slowly in cold exterior conditions.

Regarding timber species, in warm exterior conditions with sufficient exposure to moisture the curing process can proceed rapidly in engineered timber such as ThermoWood and its variants. This is also the case with Kebony and the beginnings of a silver-grey lustre can be seen within a two month period. Below is shown a DuraWood (Thermo Ayous) vertical louvres factory treated project a short while after construction.


Natural timber species show varying rates of curing to the point where a silver-grey nuance developes.

Cedar, in good curing conditions, will develop to a silver-gray appearance in a six to twelve month period. Examples of cedar projects that have developed in this timescale can be seen in the cladding gallery. One such example is this English cedar clad house on the Somerset levels at the two month curing stage and well on the way to a silver-gray surface


An example of a Western Red Cedar clad house located in Northumberland where the curing has reached a mature stage is shown below.


Siberian Larch cures very gradually to a fully developed silver-gray lustre. The following south facing sawn surface samples sited in the highlands of Scotland, courtesy of Russwood Limited, show a typical progression over a seven month period from the point of application of SiOO:X.

Image up to the right. At a project scale the following pictures show a Siberian Larch clad house at the one month after treatment stage and at the seven month after treatment stage.

Siberian larch clad house one month after treatment

Siberian Larch clad house 7 months after treatment

Siberian Larch projects where the curing has advanced to give a well-developed silver-gray appearance can be seen in the cladding gallery.

For the natural durable timbers, the expectation is that the curing process will have developed at the one-year point to a stage where a silver-gray appearance is noticeable.