Materials to use Muriatic Acid with
The harmful effects of muriatic acid highly depend on the concentration of HCl in the solution. Once diluted in water, its acidic properties become less intense.
As soon as the muriatic acid comes into contact with concrete, it reacts and produces calcium carbonate, a powder residue. Once the residue is removed, it wil reveal a porous and roughened surface underneath, suitable for any kind of coating adhesion (acid etching). The surface should not stay as it is, because the opened pores will make the surface susceptible to damage.
The washing of masonry with muriatic acid neutralizes the alcalinity of masonry and makes it suitable for accepting paints on its surface. The reaction with a strong acid makes masonry rough, or "etched," and paint adhesion becomes far easier. Similar to the case of concrete, a powdery residue is left on the surface that needs to be cleaned in order to be able to paint or coat it.
Muratic acid can be used to clean a ceramic tile floor although it isn't recommended since it dissolves some of the carbon minerals in the tile (another good solution is white vinegar). After cleaning, you should neutralize the acid first and then rinse before the floor is safe to walk on.
Muriatic acid, however, will attack most of the materials it touches, including varnish, fabrics, metals, plastics (there are some exceptions), and most paints. As mentioned above, the damage caused depends on the concentration of the solution. Even for masonry and concrete, the use of muratic acid should be the last choice, since there are better cleaning solutions such as phosphoric acid, which is less harmful. Other methods may include mechanical cleaning- sandblasting and abrasive wheels.