This may not be the right place to post this so I will post it in the home build board also, but I need some advise about acid cleaning the stone columns I just built.

I have a bottle of acid. The back of the bottle says dilute it 1:20. I saw some directions on the web that says 1:4 dilution! 1:20 does practically nothing. It removes the haze, but the not the excess spilled mortar and mortar fingerprints. I have not grouted the joints yet either, but there is a lot of mortar between many of the joints anyway just from the process of sticking the rocks to the columns. If I mix the acid 1:4, can it damage mortar and make the rocks come loose? I mean can it soak in and weaken it....or will it only eat away at the exposed mortar? I don't want to damage anything....but I would love to get the excess mortar off without having to resort to a grinding wheel. There isn't that much....but the rocks are black and every little speck of mortar really shows. thanks for the help.