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.