Dust off the cinder block wall with a dry dust mop. Start at the ceiling and wipe the mop down over the wall, shaking cobwebs and dust into a garbage can between sweeps. If the dust mop head becomes caked with dirt, take it outside and knock it vigorously against the porch or sidewalk.
Spray the wall with cleaning spray and wipe off residual dust with a rag. Double-sided tape works best on completely clean walls, so make sure there is no trace of dirt left on the surface. If you don’t have any spray cleaner, squirt the wall with a little white vinegar before wiping.
Hold the poster up against the wall and place a small “X” over each upper corner of the poster with a pencil. These marks will serve as a guide for hanging the poster.
Peel the back from one 2-inch strip of tape and place it 1 inch to the right of the leftmost “X.” Press it firmly against the wall, holding it down for 15 seconds for a secure seal. Apply a piece of tape 1 inch to the left of the “X” on the right, even with the first hanger.
Lay the poster over the adhesive strips, pushing it firmly against the wall with your palms. If the bottom of the poster curls, add another strip of tape to each bottom corner.