>I have used 3M double coated foam mounting tape for over 20 years to mount
>small exhibit labels to painted walls, but am increasingly impatient with the
>cleanup necessary.

Believe it or not we go through a somewhat convoluted process of attaching
our matboard (or foam core) labels to the wall using double-sided foam tape.
We attached the double sided tape to the back of the label and then put
heavy duty masking tape over the foam tape and use the masking tape to
attach the label to the wall.  It's worked for years!