Once fully dry (no cold spots), sand lightly with the sponge. Keep the sanding block flat so you don't dig a trench. Wipe dust.
Vertical cracks usually follow the straight vertical seams where two drywall panels meet. vertical crack in drywall
Homes near busy highways, railways, or construction sites are subject to constant micro-vibrations. Over time, these can loosen the bond between drywall panels. Assessing the Severity Once fully dry (no cold spots), sand lightly with the sponge