Mortar residue cleaning
Both bricks and tiles have to be cleaned of mortar residue after they have been salvaged. For elements installed up until the 1970s, lime or bastard mortars were used which are relatively easy to remove. This is much less the case for the cement mortars that became common afterward. Bricks are almost always (manually) cleaned before they are offered for sale. For tiles, the treatment is sometimes optional and can be done manually, mechanically, or (if they are not porous) chemically.