We are removing some pretty heavy rust on concrete with an oxalic based rust remover. It’s doing a great job on the concrete. The concrete has brick border. The job also has some larger brick areas with rust stains. We did test spots on the brick, the rust was removed but the concrete color was changed. The red of the brick was…I guess you could say dulled. It is not as red as the rest of the brick. I have read not to use the cleaner on brick with iron oxide pigment. I don’t know if the brick has iron oxide pigment or not-not sure how to tell, but maybe this could be the discoloration cause. Does anyone have another option for removing rust from brick other than oxalic, or know the reason for the discoloration.