揭开蒙娜丽莎微笑的秘密

THE Mona Lisa’s lure is so strong that Louvre Museum officials find it wise to keep her safely stowed behind bulletproof glass. She is let out of her protective cage once a year, for a whiff of fresh air. And this is when many a researcher would love to get their hands on Leonardo da Vinci’s most famous muse, in order to find out more about how she was painted.

蒙娜丽莎的微笑具有如此强烈的诱惑力，卢浮宫博物馆的管理人员认为明智的做法是让她安全地躲在防弹玻璃后面。每年会让她离开防护笼一次，呼吸一下新鲜的空气。而每年此时，也是许多研究者梦寐以求的与莱昂纳多·达芬奇最著名的缪斯女神直接接触的时候，进而从中了解这幅画作是如何绘制而成的。

For a long time, scientists and curators have wondered how da Vinci created shadows on her face with seemingly no brushstrokes or contours. Art experts call this shadowing technique sfumato—like the Italian word for smoke, fumo. Experts have long suspected sfumato shadowing has something to do with the glazes that da Vinci used above the paint layer. But proving this has been difficult because snatching a sample of the Mona Lisa’s face for chemical analysis is, unsurprisingly, frowned upon.

长期以来，科学家和博物馆馆长们一直想搞清楚一个问题，那就是达芬奇是如何在几乎不使用笔触或轮廓线的情况下，在蒙娜丽莎的脸上创造出阴影的。艺术专家称这种阴影技术为sfumato，取自于意大利语中的fumo，意为烟雾。专家早就怀疑sfumato阴影与达芬奇在颜料层上面使用的釉料有关。但是，要证明这一点很困难，因为从蒙娜丽莎的脸上取下一小块样本进行化学分析，毫无疑问是不可取的。

Instead, Louvre scientists led by Philippe Walter tried to solve the mystery using a hands-off technique called X-ray fluorescence, which can divulge details about the thickness and chemical composition of a painter’s individual brush strokes without damaging artwork. Focusing X-rays on faces in seven of da Vinci’s masterpieces, including the Mona Lisa, Dr Walter’s team found that the artist would first paint in the basic flesh tones. Then da Vinci applied up to 30 incredibly thin strokes of glaze above the flesh tone—many just a few micrometres thick.

由菲利普·沃尔特为首的卢浮宫科学家们试图另辟蹊径，使用无接触的技术即X-射线荧光解开这个谜题，这种技术可以在不损坏作品的情况下，揭示出画家个人笔触的厚度和化学成分等细节。使用射线对达芬奇7幅名作中的人脸——包括蒙娜丽莎进行仔细分析后，沃尔特博士的研究小组发现达芬奇会先画好基本色调。接着使用非常薄的釉料刷在基本色调上，最多可达30次，许多釉料层只有几微米厚。

Glaze is mostly translucent, but da Vinci would also slip in small amounts of pigments, such as manganese and lead oxides. By applying many thin coats of this adapted glaze, he achieved the smoky shadowing he became famous for.

釉料大多是半透明的，但达芬奇也会添加少量色素，如锰，氧化铅。通过使用多次调整过的薄釉层，达芬奇获得了这种让他闻名于世的朦胧阴影效果。

A paper describing da Vinci’s shadow science, published in Angewandte Chemie International Edition, also suggests that the artist was picky about his glaze recipes. For example, in the painting “The Virgin and Child with St Anne”, the virgin’s face is shadowed by glaze that contains different pigments to those in the shadowing glaze on the child. Da Vinci might have selected different glaze recipes on purpose—or he may have tweaked the painting over years during which time his taste in glaze ingredients could have changed.

一篇论文阐述了达芬奇的阴影技术，刊登在《德国应用化学国际版》（Angewandte Chemie International Edition）上，同时也指出这位艺术家在釉料配方上也是非常挑剔的。例如，在油画《圣母子与圣安妮》中，用来创造圣母脸上阴影的釉料，和孩子脸上阴影使用的釉料中包含不同的色素。达芬奇可能是故意选择不同的釉料配方，也可能是他几年时间里一直在调整这幅油画，而在此期间，他在釉料成分上的口味有了变化。

Few of the tourists strolling around the museum grounds realise that beneath them are 60 scientists, a particle accelerator and a battery of research equipment dedicated to soliciting secrets from the vast collections of French museums. The scientists who were lucky enough to get close to the Mona Lisa for this work did not have far to travel, as they work in the Centre for Research and Restoration of Museums of France—a subterranean laboratory that lies beneath the Louvre.

漫步博物馆的游客很少意识到他们脚下有60名科学家、一个粒子加速器和为研究设备供电的电池，致力于揭开法国博物馆收藏品中的秘密。这些从事这项工作，能有幸接近蒙娜丽莎的科学家并不需要走很远的路，因为他们在法国博物馆研究与修复中心工作——一个地下实验室，就在卢浮宫下面。

All, however, is not happy underground. The French Ministry of Culture wants to relocate this laboratory, as well as the Louvre’s storerooms, to a site about 50km (30 miles) outside Paris in a new facility to be built in Cergy-Pontoise. To judge from the blog started by some of the centre’s disgruntled staff, their mood is decidedly sfumato.

然而，有喜也有忧。法国文化部希望将实验室同卢浮宫的储藏室一起，搬迁到巴黎城外约50公里塞日蓬图瓦兹即将兴建的新设施中。从中心心怀不满的一些工作人员开设的博客中判断，他们的心情现在是绝对的sfumato。