Quarter sawing is a way of converting a tree so that all the planks have all the annular rings at 90 degrees to the widest face and there are many benefits in doing this. This technique is called quarter sawing because all methods involve first cutting the tree from the round into 4 quarters.
The main benefit is that a much more even rate of moisture extraction is possible as all Oak is ring porous, Black Oak particularly. When an Oak plank dries the annular rings always want to straighten out, this would result in cupping if the annular rings were parallel to the widest face. When drying a quarter sawn Black Oak plank it will just contract in its width, (by up to 1/3rd). Similarly when a fully dried out a quarter sawn plank is subjected to significant changes in temperature and relative humidity it will only expand and contract in its width without a lot of distortion. In short a quarter sawn plank of Oak is more stable.
When quarter sawn, Oak displays a section through a medullary vessel across its width. We call this medullary ray figure and this is particularly beautiful in Black Oak as the medullary vessel is very wide. Medullary vessels carry nutrients from the sap to parts throughout the diameter of the tree.
The Jubilee Oak has been milled so all the planks are sequential and they are either rift or quarter sawn.
When the first two planks from The Jubilee Oak came off the saw mill and were laid side by side on pallets, we knew exactly how this top should be put together. Not only did we know how it should look but we also resolved there and then the fundamentals of how to achieve it.
I have never been more certain of a design concept either before or since and this was dictated almost entirely by the planks themselves. There is beauty in the plank edges and the spaces they leave between them. We also realised when developing this that the joints were reminiscent of rivers which are integral to the fenland landscape.
As woodworkers we join timber in its width all the time to make panels and tops etc, but they are almost always straight joints. This is partly due to the way commercially available time is supplied and also because of the way woodwork machinery is designed to be used.
We had a fundamental challenge with the sheer scale of these planks in that it would be very difficult to manhandle planks of this length through and over standard woodwork machinery. The concept of the river joint completely changed the way we thought about how to dimension these planks and this ultimately led to resolving these construction challenges.
The river joint is an unexpected detail that also allows us the opportunity to beautifully demonstrate the lack of a growing taper, thereby giving a unique insight into the astonishing scale of this ancient tree.
For 25 years I have been trying to evaluate the viability of Black Oaks either as they are being dug up from the peat or immediately after. The very large ones are usualy broken up into random size pieces due to exposure before they were preserved. The longest one I have been able to piece together had an astonishing branchless length of 115 ft. However when these very large trees are trimmed to manageable lengths of no more than 12 ft it is possible to see the growing taper and so establish which way up they were. The stagering fact about The Jubilee Oak is that even though it was 44ft long we had no idea which way up it was. This could only mean that what we were looking at was only a small section of a much, much larger tree.
When faced with these huge trees emerging from the peat it always makes me wonder what it must have been like for nomadic family groups to wander through forests of such vast trees. The Jubilee Oak is giant amongst giants and so it was an opportunity to try and share this tantalising glimpse into the atmosphere of the ancient past. This is why we didn’t cut it into more sensible and manageable lengths.