Limewash depends on the brick drinking it in, so the wall has to be clean, sound and absorbent. Dirt and loose material are washed off. White salt crust gets noted, since it means water is moving through the brick, and a spray of water shows whether an old repellent or sealer will block the lime. Glazed or very smooth brick may not take it at all.
Leaks, open joints and sprinklers that soak the wall are dealt with first; a breathable finish helps a wall dry but does not stop new water. For the few Cedar Park homes built before 1978, removing old paint is lead-safe work under the EPA renovation rule and has to be done by a certified firm.