Is this Sibast ?  

I was recently asked about another one and some preliminary inquiries suggested that Norden Møbelfabrik might have been the maker and again the Koppels designers.  

It’s a sort of lacquered layer on wood, not sure what wood is that. To me it's not teak, but rather a lighter sort of wood (birch ?)

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And i agree that there are many elements that are shared with the construction of the butterfly chair.

I would be happy if someone could speculate about the wood type, sorry for bringing up this discussion once more.

@andersen,

If I guess stained beech (or beech with toned lacquer), perhaps someone else will follow shortly to correct me...

I think it is indeed stained, as on the side rails you can see that in some parts the stain is a bit lighter. And yes, it looks like there is laquer as it is very shiny and there are marks on the laquer that would not exist on exposed wood

It does not look like beech to me at all.  Beech has rays or ray flecks visible anywhere you look.  This looks more like mahogany to me.  

Not that I can see anything on the blurred photo of the underside but could it be that they used different wood types for the visible and the not so visible parts? The back post indeed looks like mahogany to me (or something vaguely similar) but the construction underneath the seat  could be stained beech.

Close up underseat frame

Is there any recipe for fixing scratches on the lacquer?

Again that looks very much like mahogany or maybe one of its substitutes.