Richard wrote:

O.K. I understand.
Just one additional question: and UV? If it needs painting to be
protected then I'd prefer teak veneer.
Daniel

Which will also require protection from UV...

Is it so? I admit I did not imagine such problem and your advice is very
welcome.
Do I need to glue properly shaped closing planks/veneer with thickness
greater than a minimum?
The other possibility I can envisage is to have the open end of the
fibers deeply impregnated by thinned epoxy so that at least the inner
resin will not suffer from sun exposure.
As I wrote before I would like to have my artifact appear as untreated wood.
You have been very convincing about not using polyurethane and I will
appreciate your additional input.
Daniel