The enigma of "dead-leaf yellow"

"Dead-leaf yellow." In the listed colors of his photographs, Frenchman Gustave Le Gray (1820-1884) found three precise words to define the sepia tone of some of his landscapes. But how do you return that hue to 150-year-old photos, which, until around three decades ago, nobody was interested in preserving?

And, above all, where is "dead-leaf yellow" in the Pantone color-matching guide? Gray was worried about the preservation of his works - that's why he made his lists - but what he couldn't have imagined is that a century and a half later his worry would be shared by a Texan millionaire, who last Saturday acquired his Bateaux quittant le port du Havre , taken in 1856 or 1857, in a Paris auction for 917,000 euro.

Photography restoration and preservation experts were gathered in Logroño this week to address such worries at the FotoConservación conference. The discipline is little more than 30 years old, having begun in 1975 with the opening of George Eastman House in Rochester (New York), and curators have yet to standardize their criteria.

"There are a multitude of photographic materials and processes; it is a young science," explains the conference's scientific director, Ángel María Fuentes. "There was an urgent need to standardize, to clarify protocols and to reconsider exhibition and conservation approaches."

The conference is divided into an international section, which closes on Thursday - where what is agreed "will serve as a working base for the future" - and a national part, which continues through Friday and Saturday. "We divide it because Spain has its own identity," says Fuentes, "and because in these times of crisis we are going to anticipate the cuts and decide the minimum scientific criteria for preservation."

The curators have a response at the ready for when the politicians arrive: "Maybe I can do without changing the covers of some photos, but there will be unavoidable preservation processes, and without them our cultural legacy will disappear."

All the big names in photography preservation are in Logroño, including Grant Romer, who worked at Eastman House at the start. Many of them put forward ideas, including Nora Kennedy of the New York Met, who urged her colleagues to talk with the artists. "We will never know how Walker Evans or Alfred Stieglitz's photos originally looked, but I could still chat to Richard Avedon about the preservation and exhibition [...] of his work. What the artists actually intended is fundamental, and even more so in contemporary photography, where many times the work is unique and there is no prior negative."