L'Italo-Americano

THURSDAY, AUGUST 6, 2026 www.italoamericano.org 18 L'Italo-Americano Y o u n o t i c e t h e red before any- thing else: walk into one of the great houses of Pompeii, out of the white southern glare and into the cool of a painted room, and the walls come at you in a deep, saturated, blood-and- wine red so distinctive that the world has simply named t h e c o l o r a f t e r t h e p l a c e . Pompeian red, or rosso pompeiano, as they say in Italy, is a shade you can still order today by that name from a paint chart, the color of the buried city and the ground on which its most f a m o u s f r e s c o e s s e e m t o float, from the dancing fig- ures of the Villa of the Mys- teries, to garden scenes, and little floating cupids. Across the Roman world, the deep red panel became a fashion- able backdrop for any wall w o r t h s h o w i n g o f f , b u t n o w h e r e i s t h e c o l o r s o bound up with a single place as it is here. For more than two centuries it has been one of the first things visitors carried home from Pompeii in their memory. M u c h o f w h a t w e c a l l Pompeian red is exactly that: a r e d t h e R o m a n s c h o s e , mixed and brushed on with great skill, but a surprising amount of it, it turns out, was never meant to be red at all. In recent years, scientists have combined portable X- ray fluorescence instru- ments with Raman spec- troscopy, which identifies a pigment by its molecular fin- g e r p r i n t , a n d c o n t r o l l e d heating experiments on frag- m e n t s o f p a i n t e d p l a s t e r . Their work has uncovered something remarkable: some of the Pompeian walls that glow red today were origi- nally painted yellow. The eruption itself was responsible for the transfor- m a t i o n b e c a u s e y e l l o w ochre, the inexpensive earth pigment used widely by the R o m a n s , o w e s i t s c o l o u r largely to a mineral called goethite which, when heat- ed to around 480–570°F, loses the water bound within its chemical structure and turns into hematite, a red iron oxide. The two miner- als belong to the same chem- ical family, and the differ- ence between yellow and red comes down largely to the amount of heat the iron has endured. When Vesuvius buried P o m p e i i i n A D 7 9 , t h a t heat was neither evenly dis- tributed across the city nor c o n s t a n t t h r o u g h o u t t h e eruption; yet the scorching clouds of ash and gas that swept over the town (recent estimates place successive s u r g e s a t r o u g h l y 6 0 0 – 1 , 0 3 0 ° F ) w e r e , i n s o m e places, hot enough to bake the pigment directly on the walls, turning Roman yellow into the red we see today. At nearby Herculaneum, w h e r e r e s e a r c h e r s h a v e attempted to quantify the transformation, one widely reported survey counted 246 walls that appear red today against 57 that appear yel- low. It proposed that the original balance may have been closer to 165 red and 1 3 8 y e l l o w . A n a l y s e s o f Pompeian fragments have likewise confirmed that vol- c a n i c h e a t a l t e r e d y e l l o w ochre on some painted sur- faces, although the precise extent of the change across the city remains difficult to establish. The disaster that entombed Pompeii, in other w o r d s , a l s o c h a n g e d t h e colour of some of its walls, sometimes to an even red, s o m e t i m e s t o o r a n g e o r brown. The living city may t h e r e f o r e h a v e c o n t a i n e d considerably more yellow than the excavated site sug- gests, and part of the red we now consider quintessen- tially Pompeian was created by the eruption itself. None of which is to say the Romans did not love red for its own sake, because they did. The everyday red was red ochre, an iron-rich e a r t h c o l o r e d c h i e f l y b y h e m a t i t e , d u g f r o m t h e g r o u n d a l r e a d y t h e r i g h t color and affordable enough f o r w i d e s p r e a d u s e . T h e grandest red, however, was cinnabar, the brilliant ver- milion ground from mercury ore mined far away in Spain, so costly that Pliny the Elder recorded its selling price being fixed by law at seventy sesterces a pound, and that the workers who prepared it covered their faces to keep from breathing its danger- ous dust. Cinnabar was tem- p e r a m e n t a l , t o o , p r o n e under certain conditions, light among them, to darken or blacken so that Vitruvius r e c o m m e n d e d s e a l i n g a c i n n a b a r w a l l w i t h a warmed wax preparation, afterwards heated and pol- ished, to shield it, a labour w o r t h t h e t r o u b l e o n l y w h e r e t h e p i g m e n t w a s . E x t e n s i v e u s e o f g e n u i n e cinnabar advertised both expense and status: that's why the deepest, most lumi- nous reds belonged to the finest houses. What makes the volcano's a c c i d e n t a l h a n d i w o r k s o uncanny is that Roman pig- ment-makers already knew the trick it performed: Vitru- vius describes how a painter could heat yellow ochre, in his account a lump roasted u n t i l i t g l o w e d a n d t h e n quenched, to turn it a dark- er, reddish color, and the discussions of earths and pigments gathered by Pliny show the same close knowl- e d g e o f h o w m i n e r a l s behaved. Roman workshops did on purpose, on a small and careful scale, the miner- al change the eruption later worked by accident on some walls of the buried city. The eruption, you might say, was simply the largest and least controlled kiln that pigment ever entered. To stand in a red room at Pompeii, then, is to stand i n s i d e a c u r i o u s p u z z l e . Some walls are red because a painter chose the color and l a i d i t o n t w o t h o u s a n d years ago; others because a wealthy household paid for cinnabar; and some, as pig- ment analysis has revealed, b e c a u s e t h e h e a t o f t h e eruption transformed yellow ochre already on the wall. Which of the three you are looking at, the eye alone can seldom tell. GIULIA FRANCESCHINI P o m p e i a n R e d : h o w a n e r u p t i o n repainted Pompeii An imagined reconstruction of a Pompeian interior alongside the pigments that created the reds now associated with the buried city (Image generated using Adobe Illustrator AI) LA VITA ITALIANA TRADIZIONI STORIA CULTURA

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