Cotte said: "That could explain why the eyebrows have disappeared – they have faded because of chemical reactions or they have been cleaned off. ""
柯特说：“这可以解释为什么眉毛不见了，可能是由于化学反应褪色了，或是被擦掉了。”
2
"I do not say that he was successful, in reproducing a stereo-vision effect, but if you want to achieve that this is the best way to do it," said Cotte.
柯特说：“我并不是说他在制造三维效果上做得很成功，但如果你想达到这种效果，这是最好的办法。”
3
Pascal Cotte said Leonardo built the painting up in layers, the last being a special glaze whose optical properties increased the illusion of a three-dimensional face.