Australia’s Timber Products Specialist
Western Red Cedar – Grade Data
TIMBECK Products – Select Appearance Grade
The specific grade applicable to the range of TIMBECK Western Red Cedar products is stipulated along with other data for each individual product or category. Predominately, it is Select Appearance Grade.
SELECT APPEARANCE is graded according to the particular product and for mainstream items like cladding and panelling it requires material to be free of all knots, defects and similar blemishes on the primary face. Traces of the dis-allowed characteristics may appear on the back face.
Interesting Insight into WRC Grades at Source of Supply
The following information provides an insight
into what many regard as uniquely characteristic of Western Red Cedar
and several other West Coast U.S. & Canadian species.
It does not relate to any specific TIMBECK product and is included for general information value only.
The specific grades applicable to Western Red Cedar at time of initial milling are all based on US/Canadian Grading Rules. They are:
Cut from the outermost area of the log which is generally free of knots and produces Clear grades of timber. Typically, this timber yields high quality appearance fibre in long lengths.
There are basically two different grades of Clears.
No. 2 clear
The highest grade, is virtually void of any defects although some pieces may have a limited number of imperfections. Widely used where long length clear cuttings are required such as for panelling and cladding. When remanufactured, it will yield a very high percentage of full length clear timber.
No. 4 clear
The second grade contains some small defects but of a type that does not impair the product for recovery of appearance quality fibre. A lower, more economical clear grade which permits more imperfections but is still suitable for high recovery of clear cutting by ripping and cross cutting.
Also suitable for interior and exterior trim, cabinet work, doors, mouldings and other joinery applications, especially where shorter lengths and smaller end sections are required.
Shop & Factory Grades
Cut from the middle zone of the log and tends to have larger knots, which are well spaced. This produces what is known as re-manufacturing grade timber. This type of timber is graded specifically for remanufacturing and is evaluated on the basis of the percentage of clear wood that can be recovered by ripping and cross-cutting to remove the knots. A high percentage of clear fibre can be recovered but with some shorter lengths. These grades are particularly well suited for manufacturing products where some short lengths can be utilized such and windows and doors.
Yields a minimum of 80% of total volume in clear wood cutting after ripping and cross cutting to remove defects.
No. 1 Shop – Yields not less than 50% cuttings which are clear on both faces.
No. 2 Shop – Yields a minimum of 33% clear cuttings.
Factory and Shop Grade Timber is produced for remanufacture
into short length, clear components by the user
and is graded according to the amount and size of clear wood that can be recovered.
Grain Pattern Options
While the appearance characteristics of all timbers are closely aligned to the initial cutting pattern, Western Red Cedar exhibits striking appearance contrast between back sawn and quarter sawn milling patterns. Sourcing upply of stock specifically selected to yield maximum recovery of either of these is another area in which TIMBECK specialises.
Growth rings are parallel to the short face. The long face of every board is close to a radial face. A large number of growth rings can be seen on this face.
Very large logs are required to saw large boards if they are to be quarter sawn, as the maximum depth of board is less than the radius of the log.
- best grain shows on face
- good wearing surface
- radial face preferred for coatings
- lower width shrinkage on drying
- less cupping and warp than other cuts
- can be successfully reconditioned
- slower seasoning
- nailing on face more prone to splitting
Many appearance products are backsawn. Backsawn timber is characterised by the wide face of each board being close to a tangential face, and the narrow face close to a radial face. The wide face does not intersect many growth rings and growth rings appear to be very wide apart. Some interesting patterns can be seen.
This cut offers more flexibility in that quite large boards can be backsawn from the wings of logs.
- seasons more rapidly
- prone to splitting when nailing
- wide sections possible
- few knots on edge
- shrink more across width when drying
- more likely to warp and cup
- collapsed timber more difficult to recondition
The natural characteristics of
Western Red Cedar
allow it to display startling contrasts
between Quarter Sawn faces and Back Sawn faces
Quarter Sawn Back Sawn
The traditional method of seasoning timber is to stack it in the open and let the heat of the atmosphere and the natural air movement around the stack remove the moisture. Each piece is separated from the next by regularly spaced “stripping sticks” or “stickers” which between them, provide the void which allows air movement. The process has undergone a number of refinements over the years and air seasoning is now regarded as the best method of removing excess moisture from timber.
The two locations of the TIMBECK manufacturing facilities are ideal for air drying of timber. TIMBECK uses only accurately dimensioned “stickers” to eliminate board distortion during the drying process.
A number of commercial processes for seasoning timber are available, the most common of which is kiln-drying. Kiln drying accelerates the process of seasoning by using external energy to drive the moisture out. The timber is stacked in much the same way as it is for air drying, and is placed inside a chamber in which the conditions can be varied to give best seasoning results. Air is circulated around the charge (stacked timber) and the temperature and humidity can be varied to give optimum drying. Each species has different cell characteristics and therefore requires different drying schedules. Typically the timber may be in the kiln for a period of between two days to one week, largely dependent on the moisture content at the commencement of the kiln drying process.
Shipping Dry is the term used to loosely describe the state of moisture content of Western Red Cedar (and other West Coast species) which is anywhere between Green and Seasoned. It’s origin is a reference to the natural loss of some moisture which occurs during the shipping period.
Green or Unseasoned timber is material where the moisture content is at or close to the level that prevails at the time of original sawing from the log.