Interwood Forest Products – Shelbyville Kentucky

Cathedral Grain Structure in Flatcut Logs

The Cathedral is the resulting grain structure after a log has been flat-sliced or “flatcut”. It’s called this due to its resemblance to a cathedral. As pictured, the log is sliced in half and then further sliced into veneer starting from the outside of the trunk moving inwards.

A diagram showing a flatcut log and it's resulting "cathedral" grain structure.

The size and shape of the cathedral will depend on the size and shape of the trunk and not all trees grow perfectly straight. In fact, it’s rare for a tree to ever be perfectly straight. There is usually some bend each growth period.  The diagram below shows a tree trunk being sliced into three sections. Each section will be fashioned onto the slicer seperately. Due to the irregular growth of the tree, each section will result in a different type of cathedral structure.

A diagram of a tree trunk being sliced into three sections, each section resulting in a different type of cathedral grain.

The three types of cathedral are:

One-Directional Cathedral

Flatcut Walnut veneer with one-directional cathedral grain structure.


Island or “Football” shaped cathedral

Flatcut Walnut veneer with island or "football" shaped cathedral grain structure.


Non-Descript cathedral

Flatcut Walnut veneer with non-descript cathedral grain structure.


While the One-directional cathedrals is most desired there are spectacular projects which utilize all parts of the cathedral coming from one log. Below is a project by Indiana Architectural Plywood in which an entire Teak log was used in a cluehouse corridor, creating visual interest with its variety as well as driving the visitor forward with the horizontal application.

A Teak veneer project using flatcut Teak and all types of its cathedral grain structure.