“Even though the ancient Egyptians were probably the first to gild artwork with it, the Japanese have long been credited as being able to produce the thinnest gold leaf in the world.”
Via R&D 7/02/2014
Ancient Japanese gold leaf artists were truly masters of their craft. An analysis of six ancient Namban paper screens show that these artifacts are gilded with gold leaf that was hand-beaten to the nanometer scale. Study leader Sofia Pessanha of the Atomic Physics Center of the University of Lisbon in Portugal believes that the x-ray fluorescence technique her team used in the analysis could also be used to date other artworks without causing any damage to them. The results are published in Springer’s journal Applied Physics A: Material Science and Processing.
Gold leaf refers to a very thin sheet made from a combination of gold and other metals. It has almost no weight and can only be handled by specially designed tools. Even though the ancient Egyptians were probably the first to gild artwork with it, the Japanese have long been credited as being able to produce the thinnest gold leaf in the world. In Japanese traditional painting, decorating with gold leaf is named Kin-haku, and the finest examples of this craft are the Namban folding screens, or byobu. These were made during the late Momoyama (around 1573 to 1603) and early Edo (around 1603 to 1868) periods.
Pessanha’s team examined six screens that are currently either part of a museum collection or in a private collection in Portugal. Four screens belong to the Momoyama period, and two others were decorated during the early Edo period. The researchers used various x-ray fluorescence spectroscopy techniques to test the thickness and characteristics of the gold layers. The method is completely non-invasive, no samples needed to be taken, and therefore the artwork was not damaged in any way. Also, the apparatus needed to perform these tests is portable and can be done outside of a laboratory.
The gilding was evaluated by taking the attenuation or weakening of the different characteristic lines of gold leaf layers into account. The methodology was tested to be suitable for high grade gold alloys with a maximum of 5% influence of silver, which is considered negligible.
The two screens from the early Edo period were initially thought to be of the same age. However, Pessanha’s team found that gold leaf on a screen kept at Museu Oriente in Lisbon was thinner, hence was made more recently. This is in line with the continued development of the gold beating techniques carried out in an effort to obtain ever thinner gold leaf.
“This simple comparison allowed establishing a timeline between the manufacture of two pieces attributed to the same period, proving that X-ray fluorescence techniques can be an important asset in the dating of artworks,” says Pessanha.
Read the full article at Springer: Comparison of gold leaf thickness in Namban folding screens using X-ray fluorescence Pessanha, S. Et al., (2014) DOI 10.1007/s00339-014-8531-z Excerpts follow:
“In this work, the thickness of the gold leaf applied in six Japanese folding screens is compared using a nondestructive approach. Four screens belonging to the Momoyama period (~1573–1603) and two screens belonging to the early Edo period (~1603–1868) were analyzed in situ using energy dispersive X-ray fluorescence, and the thickness of the applied gold leaf was evaluated using a methodology based on the attenuation of the different characteristic lines of gold in the gold leaf layer. Considering that the leaf may well not be made of pure gold, we established that, for the purpose of comparing the intensity ratios of the Au lines, layers made with gold leaf of high grade can be considered identical. The gold leaf applied in one of the screens from the Edo period was found to be thinner than the gold leaf applied in the other ones. This is consistent with the development of the beating technology to obtain ever more thin gold leafs. …
Gold was one of the ﬁrst metals manipulated by men Because of its remarkable malleability, which makes it easily beaten to form the desirable shape . Its noble metal stability and resistance to tarnish gives durability to The objects on which it is applied to. Its suitability to adorn small or larger areas renders it an excellent material and the ﬁnest among metals for use in the decoration of artworks.
Two different terms have been employed to deﬁne metal sheets of varying thickness: foil and leaf. The former is generally used to describe a sufﬁciently thick sheet that can support its own weight while the latter, which mainly
applies to gold, refers to a very thin sheet that has almost no weight and that can only be handled by specially designed tools.
With modern technology, the gold leaf can be obtained as thin as 0.1 lm ; however, the thickness of the leaf used in ancient artworks could be as thick as the 5–10 lm applied in an Egyptian 50 BC ceramic masque, or as thin as
0.2–0.5 lm used in the gilding of medieval Islamic glazed ceramics . According to Koyano , the Japanese gold Leaf is said to be the thinnest in the world. …
The gold leaf applied to six Nanban screens was compared, and the leaf applied to the screen kept at Museu Oriente was found to be the thinnest. … Considering that the thickness of the gold leaf tends to decrease significantly with the advent of gold beating technological development, these results are indicative that this specimen from Museu Oriente is the most recent. This comparison allowed establishing a timeline between the manufacture of two pieces attributed to the same period–from 1603 to 1868, proving to be an important asset in the dating of artworks.” End of excerpt.