Tempered wood it's a ancient Japan technique to toughen surface against decay. The higher temperature of a process the higher ratio of carbonization at the same time more even surface of a shingle.
Texture of charred spruce particularly interesting when observed from side angle. Then its reflect light glistening like lizard's skin.This effect especially can be seen after rainfall when surface is wet starting to shimmering the surrounding.

Charred spruce shingles-specifications

Despite unique of each shingles main measurements parametrs could be summed up in following sizes shown on drawings bellow.
Lengths 30-40-50 allows to select shingles depending on designed plan and anticipated divisions.

Widths 6-16,5 cm helps execute tights surfaces use technique to lay shingles doubled lap or triply lap.

Smaller thickness a the end of a shingles covered another layer reduce use of raw material doesn't reducing durability or protecting features of a whole surface.
It's make them more elastic which give a chance to shaped them in more organic way if there is such a need.

Chamfer of a edge (seen on picture) ease escape water from the surface of a shingles.