quarter sawn timber (lumber)
The above images show how a log is converted to quarter sawn timber.
The image below shows a quarter of an actual log, which has been quarter sawn as described above.
Image above is of a quarter sawn Ned's plat in London Plane. Note the growth rings perpendicular to the broad faces; indicative of pure quarter sawn timber.
indeco choose to use quarter sawn timber for their Ned's plats as it provides greater stability and better wearing properties. And the best way to quarter saw timber is as follows: firstly, the log is cut into quarters. Then the quarter is rotated 90 degrees back and forth to saw off one board at a time.This process does take more time hence the higher cost of quarter sawn timber but the big advantages are: a more stable timber as already stated plus it is easier to dry and it will highlight certain desirable characteristics such as ray fleck (as per this piece of banksia), fiddleback grain, ribbon grain, interlocked grain etc. And this method of quarter sawing also produces little waste.
The best way to check whether a board is quarter sawn is to look at the end grain and view the orientation of the annual rings which should be approximately perpendicular to the wide faces.
In order to get a size 23 (230mm wide) Ned's plat, for instance, one would probably need a log of approximately 650-700mm diameter, allowing for shrinkage and by the time one cuts off the sapwood/bark and the juvenile wood around the pith (centre of the log).
Definition of quarter sawn: True quarter-sawn boards are those which have growth rings at an angle of 80-90 degrees to the broad face. Anything between 45-80 degrees can be classed as quarter-sawn, but not "true" quarter-sawn. In the photograph above; boards A, B, 1 & 2 would be true quarter-sawn, the rest would qualify as regular quarter-sawn apart from the triangular section F6.
Whilst the definition of back-sawn is: a term used in Australia to describe a board which is cut such that the growth rings are approximately parallel to the broad face.
The other main method of timber conversion is known as Live Sawing; which means the sawing of boards in a series of parallel cuts without re-orienting the log. A simple and economic method for rapid mass production.
See back-sawn article here.
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