The two commonest effects are efflorescence and spalling. Efflorescence can often be removed from concrete using phosphoric acid. It occurs as colorless to white, soft isometric crystals and efflorescence coatings. Further, the efflorescence due to salts in water reduces the life of the concrete filter. Secondary efflorescence is akin to osteoporosis of the concrete. If the water evaporates, the minerals remain as the so-called efflorescence. The effect of saltpetre is to leave a white efflorescence. However, if the source of the water penetration is not addressed efflorescence may reappear. Surrounding groundwater forms efflorescence used by many antelope as salt licks. In some instances, the resultant efflorescence obscured painted images. The resulting white deposits are referred to as "efflorescence" in this instance. The Habsburg years also ushered in the Spanish Golden Age of cultural efflorescence. And while it will help to protect against efflorescence, it cannot permanently prevent the problem. It is found only as an efflorescence in very dry environments. At the age of over seventy obtained a method for [making] "efflorescence of vermilion" pills.