Siding gets chard and reveals natural texture and shine.  Thie charcoal layer is naturally insects resistance.  The black color will not fade away unless the top layer is scraped.

It is hard to find chemical-free wall/wall finishes today.  One rare method to achieve that is mud clay wall.  Mud and clay are often dug up near construction sites and mixed with organic fibers such as straws so the wall does not crack.  Colors change depending on the mud and clay.

Lime is a produced from line stone or anything with high calcium content such as seashells.  When the lime is mixed with organic fiber and water, it becomes lime plaster.  Its alkaline chemistry resists mold, insects, and rodents. Lime is naturally white or creamy white.