Featured age, origin and decor name ?? glass carafe / decanter ?

I'd wait a while. It won't hurt the glass and will eat the gunk.

 

Agreed. Give it half an hour or so.

 

Simply said, Secessionism is Austrian Art Nouveau.
Secessionist designers were among the ones who experimented beyond the usual Art Nouveau and Jugendstil (German Art Nouveau) shapes. Often combining the linear designs of Jugendstil with organic designs without the 'whiplashes' you see in French, Belgian, and Dutch Art Nouveau.
Secessionism also spread to Vienna's 'sister city' Prague in nearby Bohemia, so Bohemian is certainly a possibility.
These more experimental styles evolved into Art Deco, which, contrary to popular belief, had its beginnings in the early years of 20th century Europe.

Maybe more familiar: A related type of "Art Nouveau Plus" can be seen in the art of the Glasgow Four, with Charles Rennie Mackintosh as most famous name.

 

I first used 1 tablet and waited 1 hour. it helped a bit but still didn't get clean enough.

then 1.5 tablet used again waited an hour ... but still that label is not gone and i still see some dirt at the bottom.
now i have used 2 tablets and want to wait 2 hours. maybe then it dissolves.

And thanks @Any Jewelry for the additional info. Its very helpfull

 

Try one of those long thin bottle brushes, along with the denture tablets.
There are bottle brushes with soft tips, they are the kind you need. Some of the others have nasty wire ends that scratch the glass.

 

Could it be limescale in there?
I regularly have to use Viakal on the inside of vases to get rid of it as we live in a very hard water area. It also destroys pipes, washing machines and dishwashers given half a chance but that’s another story.
Don’t do it without checking with the experts up there ^^^ and don’t let it get near any paint or decoration

 

In that case maybe try vinegar first? @Ownedbybear ?

 

It might be limescale, worst case is glass sickness. I'd try vinegar first, doesn't matter if it's brown or white. If you can get them, there are llittle copper balls you can swirl round which help remove crud. If all else fails, then limescale remover gel, very very carefully so it doesn't get on the outside.

If neither of those work, it's glass sickness and not a lot to be done.

 

OTOH if some of it came off there's a good chance it's just crud. If you don't have copper balls, there's always pie weights. (small balls or a chain of same used to keep an unfilled pie crust in place while baking)