There’s no need to resort to expensive, strong products to attack limescale. Much better to stick to homemade remedies, which are just as effective, and a lot cheaper. If your chrome showerhead is caked with scale, unscrew it, and steep overnight in a bowl containing half clear vinegar and half warm water. In the morning the scale will flake off and the head will only need a little rub with a cloth. Note: don’t use on special metal finishes, as vinegar can damage. For scale in an enamel bath or porcelain sink, dampen a pumice stone and rub away at the mark. Don’t worry about scratching: the pumice is hard enough to deal with the scale but soft enough not to damage the surfaces