timber finishes | timber treatment
Preschem has recently re-released it’s Radial Timber Sealer product. However, it’s a new high tech formulation from the ground up! This wood finish was originally designed for Radial Timber* projects, where the architect or customer wished the timber to weather off to that silver-grey look, while protecting it from the elements. As far as timber finishes go this is a specialist product and as such, may not be very well understood. Hopefully this post will explain clearly the features of Radial Timber Sealer. We’ll start at the beginning which means a quick lesson on timber and dimensional stability.
All wood has a natural moisture content. This moisture content varies significantly depending on a number of factors such as is it “green” meaning unseasoned through to being properly processed and dried such as kiln dried. Typically Australian Eucalypt timber that’s “green” has a moisture content (MC) as high as 80%. Kiln dried timber will be between 11-15%.
The significance of this is when timber changes MC it shrinks if it’s drying, but expands if it takes up moisture. Rapid changes in MC can cause issues such as warping, cupping, splitting and checking. What happens is the outer surface shrinks or expands rapidly, but the timber under that surface takes longer to change MC, so internal stresses are created. This is dimensional instability and is to be avoided where possible. When timber is processed from green to kiln dried, it is done slowly and carefully to avoid this. However, even timber that has been properly kiln dried can still have splitting and checking occur when its placed in a weather exposed situation, especially without any finish applied. The wood will still adjust it’s MC to its environment and this process is called seasoning. Seasoning will also cause dimensional stability issues.
Where the ultimate goal is to have the timber weather off to a pleasing silver-grey but prevent the issues of splitting, cupping and checking. You thus need a timber finish or wood treatment such as Radial Timber Sealer. Its key features are:
- Once off application for newly installed durable timber, where the desired result is to weather naturally
- Unpigmented and contains no UV agent so allows the timber to turn silver-grey
- Clear finish formulated to control moisture and even stops wetting for around 6 months
- Highly effective moisture control for 12 months allows the timber to completely season naturally
- Contains a powerful mouldacide that prevents sapstain or bluestain moulds during seasoning
If you wish to maintain the timber’s “new look” rather than allow it to go grey, then the timber finish product to use is Aussie Clear for mid to dark toned hardwoods, or Aussie Clear Light for blond and lightly coloured timber. Exterior Pine Clear is the recommended product for Treated Pine.
* Radial Timber Sales is the wholesale/retail arm of Radial Timber Australia. Both companies are part of our wider business group. The Radial technology of cutting sawlogs is unique technology that allows very high yields from smaller plantation or new growth logs, while improving dimensional stability. Visit radialtimbers.com.au for more information on the technology and product profiles.