When framing a poster make sure you tell your framer that your tastes may change and you might want to re-frame your poster in the future so you may need to take the poster out of the frame and you don’t want any nasty surprises.
I was personally burned once. I asked for acid free matting and several years down the road I decided to take the poster out of the frame, only to discover that the poster had sever acid burns around the borders.
This resulted in to a nasty tear in the upper left corner and him with a bad taste for Framers.
It was sent to me for tape removal, linen backing and restoration. It’s all good now!