We mainly work with 2 species of wood : spruce and siberian larch.
Spruce can be installed inside without any treatment. If it has to be installed outside we recommand you order treated boards (autoclav Classe IV or D) against humidity and bugs.
Siberian larch do not need usually any treatment because it has a very high ability to withstand water. It has as well a very good capacity to resist fire and has the Euroclasse C-s2, d0 grade. This species has very few, or not at all sapwood. Thus the risk of financial loss is drastically reduced. Plus, most of european countries ban sapwood for outside installation.
Some competitors may recommand douglas species which can be easely found in western Europe. This is really a bad idea. This species has pretty bad fire resistance grad ( Euroclasse D-s2, d0), lot of sapwood and most of time, result after charring is quiet ugly. Douglas is clearly adapted to construction, not so much to decoration, especially wood charring.
Lot of houses in Venice are carried by posts made of siberian larch. Not douglas.

Boards we propose respects SF 1-4 quality grad. This means that some boards have knots, even sometimes big knots, which give a wonderfull aspect after charring. We manage to not sale boards with black and/or falling knots and no missing material on the visible side.

Regarding “Crocodile” charred finishing we recommend spruce species. Result is really gorgeous and spectacular.
Siberian larch is suitable as well, but do not give a so impressive effect as spruce. In another hand, you may have no choice and have to use siberian larch which is specifically adapted to humid areas.
Both spruce and siberian larch are perfectly suitable to “Dark Burnt” and “Light Burnt” charring.

“Crocodile” and “Dark Burnt” finishing charring do not result naturally in a uniform black color, especially with boards with profils which have corners or trough. To overcome that we propose black tinted specific product (CWT – Charred Wood Treatment) or stain without any extra cost. In case of rectangular profiles, this may be not suitable and you may prefer colorless resin or stain.
Black tinting prevent as well a later possible color alteration of the stain and the CWT.

Stain : we use a stain (CWT) wich is an elastic product, scraches and blows resistant. We recommand 2 coats for an inside installation and 3 coats for an outside installation.
This CWT is a very special product which is specifically dedicated to charred wood. It is not a resin, nor an oil, nor a lasure, this is really a specific product. It is adapted to any weather conditions and is blow resistant. This is an elastic product which respects the dimensions variation of the boards over time, mainly to humidity variation.
We recommand CWT for outside, 2 coats.
Important note : some salers propose acrylic resin. This is definitively a bad choice. Acrylic resin, after drying, is very rigid and can not follow boards dimensions variations. Result will be ugly cracks and crevices.

We are using the very best products to protect the wood, but this will not prevent the wood to suffer the consequences of weather contraints. Aspect of the charring and color of the wood can evolve, mainly due to UVs effects.
As we are using siberian larch, there will be no problem regarding resistance and durability of the boards, at least for the next 50 years. It is mainly the general aspect which may change.