Light stuff can sometimes be removed with muriatic acid (hydrochloric acid). Thick concrete would have to be chipped off first. Test an area.
http://search.yahoo.com/search?ei=utf-8&fr=slv8-hptb6&p=46202 roof cleaning&type=Actually the only difference between Portland concrete and Portland mortar is the aggregate. That's coming from an old construction guy not an experienced PW contractor so I could be wrong. Muriatic acid reacts with the calcium in both. I'm talking fired red brick. You can cause a mess if you don't know what you're doing.
That being said I highly recommend you listen to Celeste. Don't ask someones advice and then ignore it. You waste your time and more importantly another persons time that has nothing to gain.
Andy - Main reason I'm going to tell you NOT to do that is that we have spoken multiple times on the phone. You don't need to be putting muriatic on brick at this point in time.
Concrete and mortar are different compositions.
Muriatic when used improperly can RUIN brick.
Considering your experience, applying muriatic to an unknown brick (you didn't say what color or type brick it is) could be disastrous at best.
Do you know if what you're dealing with is concrete or residual mortar?
Andy - Main reason I'm going to tell you NOT to do that is that we have spoken multiple times on the phone. You don't need to be putting muriatic on brick at this point in time.
Concrete and mortar are different compositions.
Muriatic when used improperly can RUIN brick.
Considering your experience, applying muriatic to an unknown brick (you didn't say what color or type brick it is) could be disastrous at best.
Do you know if what you're dealing with is concrete or residual mortar?