Preservation
Due to the instability of Han purple, it shows significant signs of weathering on archaeologically excavated artifacts. The copper(I) oxide formed in the decomposition of Han purple (see section on color) remains stable, but Han purple continues to deteriorate and so its purple color increases with time.
Han purple fades in acid, so colorless particles found in pigments containing Han blue and Han purple may be particles which were originally purple but which faded in acidic conditions in burial. In addition, Han blue has fungicidal properties and so preserves better. Han purple reacts with oxalic acid to form BaCu(C2O4)2. The light blue color of this salt may explain the light blue color of some of the Terracotta Warriors' trousers - the color resulting from the presence of oxalate-excreting lichens.
Read more about this topic: Han Purple And Han Blue
Famous quotes containing the word preservation:
“There is something to be said for jealousy, because it only designs the preservation of some good which we either have or think we have a right to. But envy is a raging madness that cannot bear the wealth or fortune of others.”
—François, Duc De La Rochefoucauld (1613–1680)
“I do seriously believe that if we can measure among the States the benefits resulting from the preservation of the Union, the rebellious States have the larger share. It destroyed an institution that was their destruction. It opened the way for a commercial life that, if they will only embrace it and face the light, means to them a development that shall rival the best attainments of the greatest of our States.”
—Benjamin Harrison (1833–1901)
“The bourgeois treasures nothing more highly than the self.... And so at the cost of intensity he achieves his own preservation and security. His harvest is a quiet mind which he prefers to being possessed by God, as he prefers comfort to pleasure, convenience to liberty, and a pleasant temperature to that deathly inner consuming fire.”
—Hermann Hesse (1877–1962)