This might sound a little strange, but we have some new French doors that
I've just put in...all fine, apart from the fact that the doors are just a
little too keen to swing open, and I'm nervous that someone will give it a
push and it'll swing merrily into the wall.

I'm therefore looking for a simple (but not ugly) way to create a little
additional friction in the hinges such that the doors stop naturally without
whacking into the wall.

Is there such a thing as 'friction grease'? Or maybe something else that I
haven't thought of...? I'm not keen on adding any additional mechanical
devices as these would be obtrusive in this position.

Your thoughts are appreciated!

Phil