I'm building a simple shelf that will hold something weighing 5–10 kg. One thing I haven't decided yet is what I should use to attach it to the wall.
I have two surfaces made of different materials. Look at picrel, surface A is metallic and painted, while surface B is a painted concrete wall. I need something like double‑sided tape, glue, or any other adhesive that can support that weight but can also be removed or dissolved with a chemical without damaging the paint after 6 months.
What should I look for? I don't want to use screws left holes.