Picked this up, the sticker indicates "West Germany" which dates it to 1945 - 1990 or thereabouts. It is unused and mint. What would you do, put it on the shelf or use it?
Use it. If it doesn't work then put it on a shelf. Maybe in a vintage mug for display. But brushes were meant to be used first and foremost. Nice brush by the way!!!
I would keep it also. If it's a vintage brush that's been used, I have no problem continuing to use it. When something is old and has never been used, it's more of a collector item for me.