chartek spec 2019 - chartek – nz's only commercial
TRANSCRIPT
But it’s not actually a new
product, it is an ancient Japanese
technique of preserving and finishing
wood by charring it with fire. There are many
examples of charred timber farm buildings in Japan that
are hundreds of years old and still going strong.
Surface treatment;
Charring is considered a surface treatment in New Zealand and has been approved
by councils across the country. The integrity of the timber is not impacted, as such, the
warranty offered by the timber supplier remains valid.
* We are frequently asked about a light char, but we would not recommend this as a product as the cellulose will not have been degraded enough to provide adequate protection. To achieve a similar look, we would recommend the charred and brushed product with a black stain included in the oil.
chartek.co.nz | [email protected] | +64 (0)27 274 6103
CHAR OPTIONS
Shou Sugi Ban is a rapidly growing modern trend in Western architecture, particularly with energy conscious and sustainable house builds.
LIGHT*
(BRUSHED)MEDIUMHEAVY
• Resistant to rotting.
• Hardening oil is used to lock in the charcoal. This reduces flaking and particulate release. White shirts can rub against surface without marking!
• Historical data shows that charred timber can last 80 years or more, and in the right environment potentially much longer.
• Chartek uses durable timber species or products to ensure its timber is approved for use as exterior cladding in its own right and therefore no special certification is necessary.
• Councils in the major New Zealand cities have approved this product which sets a precedent and provides confidence for customers.
• The main characteristics which contribute to increasing the durability:
• Surface thermal modification The micro structure of wood is made up of a lattice of material called lignin which supports a soft cellulose material within its structure. Lignin is a natural polymer which is resistant to rot and indigestible for insects, while cellulose is a sugar, which is both digestible and susceptible to rotting. When timber is subjected to flame, the soft cellulose is degraded, leaving the hard lignin exposed to the surface, which is less reactive to water & resistant to digestion!
• Barrier formed by charcoal layer Charcoal is more hydrophobic than timber, but porous. This means water can be held within the porous macrostructure but will not penetrate into the microstructure of the charcoal, therefore is likely to be able to evacuate and dispel the moisture quickly.
• Oiling of charcoal barrier A hardening oil can be applied, which soaks through the full depth of charcoal and into the timber surface, then hardens and sets like a resin.
• The oil fills the porous cavities of the charcoal and sets, thus removing the ability to hold water at all (waterproof).
• The hardening oil sets the charcoal lugs in place, locking in any friable particles and creating a more durable, hard surface which doesn’t rub off on clothing.
• Charred timber requires significantly less maintenance when compared with standard timber. This may be as simple as a light yearly wash down to remove dust.
• Maintenance schedules will vary depending on the environmental conditions at unique installations and depending on what each customer wants from their product (refer to visual expectations over).
• Current testing indicates reapplication of oil (to maintain the charred look) may only be necessary every 5-10 years (this is subjective).
DURABLE
MAINTENANCE
• Superior alternative to petrochemical stains or paints.
• Sustainable, natural process.
• Patina • If this product is charred, erected on a house and left, it will change and
evolve over time. It will in time, fade, pockmark and the charcoal lugs will fall off (we’re talking decades).
• Some people celebrate the patina, the changing colours and imperfections which comes with the age of this product. The earthy, organic effect does create a beautiful juxtaposition with clean, precise modern materials like steel and glass.
• Precision • Some people decide they want the product to remain looking like it did
when new. Chartek have successfully developed a method to slow the effects of ageing by applying a hardening oil which is absorbed through the depth of char and into the timber. This sets hard like a resin, locking it all together. We anticipate that the way a customer wants their product to remain looking will come down to varying degrees of maintenance by reapplying new coats of oil intervals. Testing has exhibited promising results.
• The NZ standards authority currently haven’t formally tested and validated charred wood, however this was one of the very reasons why the Japanese developed this technology to protect their valuables.
• In most conditions charcoal is less likely to ignite than standard timber. When it does, the flame propagation rate is slower.
• Charcoal has a lower ignition temperature than standard timber, but a higher resistance to ignition from low density energy sources (eg. sparks which have high temperature, but low energy density).
• Charred timber has been certified in the United states to achieve a Class B flame spread rating.
• Timber species currently offered by Chartek are Siberian Larch and thermally modified NZ pine (sourced from Abodo), but we are aware that there are other species which also present plausible products. Each distinct species presents a unique visual effect and we are happy to test custom requirements.
• We can also provide a charred and brushed product from Siberian Larch. This provides the surface durability of the charring process and presents a beautiful textured relief with raised growth rings.
chartek.co.nz | [email protected] | +64 (0)27 274 6103
VISUAL EXPECTATIONS
FIRE RESISTANCE
TIMBER RECOMMENDATIONS
EVIROMENTALLY FRIENDLY
