How to Clean old bricks?
I use an air chisel to clean bricks when saving for projects. There are usually 2 kinds of bricks in chimneys an inner layer that is fire brick, this brick can be hard to save as it is porous and not as strong as structural brick they hold the fire clay better but also are easy to crack. The structural bricks are heavier and stronger usually just a few taps at a sharp angle with an air chisel pops the mortar off, the same could be done by hand with a chisel and hammer.