The checklist starts with absorbency: a few drops of water show whether an old water-repellent sealer will block the lime. Next comes efflorescence, the white salt bloom that means moisture is moving through the wall. Last, moss, dirt and loose material are washed off so the brick is clean and sound.
Anything that keeps the wall wet, from open mortar joints and split caulk to overflowing gutters or earth piled up against the brick, is repaired or pointed out before finishing, since breathable limewash lets moisture out but does not cure a wet wall. Paint disturbance on a pre-1978 house, whether scraping or stripping, is work Washington’s renovation rules reserve for a certified firm using lead-safe practices.