Adrianne’s Reviews > The Brilliant History of Color in Art > Status Update

"Pompeian red" was popular in the 18th century. "But red ocher is actually a dehydrated form of yellow ocher, meaning that extreme heat, say, from a volcanic eruption, could drive off the water in yellow ocher and turn it red. In 2011 scientists ... presented a paper suggesting that up to half of the 246 apparently red ocher walls in Pompeii & nearby Herculaneum were actually yellow ocher before the volcano erupted."