What's an alternative to blue tack that won't stain the walls?

Question

I heard white tack is just as bad...is there some sort of temporary fixative for sticking photographs up that won't mark the walls in any way?

Answer 1

I have used hot glue in my classroom (cement walls).  I put it on the back of my posters, put them up, let the glue dry.  When I take them down, I just peel the dried glue off and everything is fine.  You can't move the picture until it is dry.  If you try to move it with hot glue, then the paint will peel.  I do not know if this works on dry wall or not.