The SiOO X Story – Protecting the Planet - Book - Page 35
Chapter 5
Wood and the Weather
Although wood is an incredibly versatile and beautiful material it
does suffer from some problems. For exterior applications in Use
Classes 3.1 and 3.2 (EN 335 Part 2) wood in exposed conditions
will weather to give a silvery grey driftwood appearance. However, when wood is sheltered (such as under overhanging eaves)
then the wood will retain its original colouration. This leads to
the very unsightly appearance of uneven weathering, examples
of which are, unfortunately, not hard to find. The weathering of
wood has been researched for over 100 years and although we
understand very well why it happens and what causes it, there
has never been a solution developed.
penetrates the wood where it gradually forms an inert glassy
polymer, by reaction with atmospheric carbon dioxide. The second component acts to seal and protect the first application
until it is fully cured, but it also forms an inert water-resistant
envelope which penetrates the wood and gradually creates a
grey surface appearance. It does not stop the lignin from degrading, but it takes the same role by keeping the wood cells
glued together, essentially using the strength of glass. Just as
important, the wood now has an even weathered appearance
once the protection system cures. This means that the unsightly
patchy weathering of exterior wood cladding is no longer a
problem. SiOO:X Wood Protection locks in the beauty of wood.
The SiOO:X polymers that form in the wood have silicon-oxygen
bonds, the same as in glass, and are completely UV stable.
Conventional wood coatings rely on adhesion to the wood surface for their integrity. Over time, the movement of the wood
under the coating due to the effects of wetting and drying result
in localised failure of the coating, usually at the early-wood/
late-wood boundary. Once this happens, liquid water is able to
penetrate below the surface of the coating, which is then forced
off due to hydrostatic pressure. The only way to stop this from
happening is to use more flexible coatings, but this is not feasible because the coating would then be tacky and collect dirt
very rapidly in service. Conventional paints and varnishes also
use carbon-based chemistry which, are susceptible to UV degradation when exposed to sunlight. Clear coatings suffer from
the additional problem that the wood underneath is degraded
by UV light and failure occurs because the surface layers of the
wood start to lose their structural integrity. Putting UV stabilisers
and filters in the coatings may slow down this degradation to
some extent, but it is the wood that is the Achilles heel in the
clear-coating system.
The SiOO:X Wood Protection System is different; it is not a coating, but an envelope which interacts with the surface layers of
the wood. The protection system has two components; the first
Restoration of badly weathered oak statue in Scotland (2013).
Photo: Alan Coultas.
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