How can I remove the white effervescent stains that are appearing on my brick pillars?
Without seeing the stains, I can not be certain, but it sounds as if you are experiencing “bloom”. This is a situation where some of the lime contained in the mortar is leaching out and being deposited on the surface of the columns. If this is what it is, the easiest way to clean it is with muriatic acid. You can spray it on, let it sit for a while and scrub with a stiff brush. Make sure you use gloves, and wash it down with plenty of water afterwards.
