Cleaning white mortar residue from brick?

Brick masons use a solution if Muriatic acid and water. About a 50/50 mix of acid and water. Be careful when mixing and using the acid and be sure to use gloves. Use a wire brush dipped in the solution and scrub the hard to reach places. For the brick faces, just use a piece of brick dipped in the solution and rub the other bricks. After cleaning, spray off with water hose so the acid doesn't keep eating away at the mortar. You can by Muriatic acid at any pool and spa store by the way.