Power washers, sand blasters, chemical solvents and commercial paint removers can remove spray paint from brick walls. Since brick is a porous surface, which means that liquids can penetrate it, commercial cleaning agents should be sufficient for this type of surface.
It is always easiest to remove spray paint from brick right after it is applied. When spray paint is accidentally aimed at a brick wall or when vandals graffiti a brick structure, it is important to react quickly.
In some cases, spray paint will come off brick walls when a pressure washer or sand blaster is aimed at the paint. The strength of the water or sand stream peels off the spray paint until it is no longer visible. However, soda blasters or sandblasters might leave behind a visible shadow that can ruin the appearance of the brick.
Commercial solvents and cleaning agents are the best option if pressure washers or sandblasters do not work. Apply a solvent that is intended for use on porous surfaces based on the manufacturer's instructions. Always wear appropriate safety gear when working with harsh chemicals. A respirator might be necessary, for example, especially when the user is not working in a ventilated area.
Brick features numerous small divots and holes in the surface. If it is impossible to remove the spray paint completely, there is always the option of painting the entire wall or surface to disguise the graffiti or accidental paint spray.