In this episode, we will return to the topic of “seals.” In the previous episode, we mentioned that emperors had their own unique seal systems, with two of the largest collectors being Emperor Huizong of the Song Dynasty and Emperor Qianlong of the Qing Dynasty. Emperor Huizong had the “Xuanhe Painting Academy,” while Emperor Qianlong had the “Shiqu Baoji” series. This episode will primarily focus on the seals themselves, which are important tools related to artwork. The materials used for seals can also help in distinguishing genuine from fake items. For example, if a certain dynasty had stopped using metal seals, but a work is found with a metal impression, it can be inferred that it is a forgery.
During the Han Dynasty, seals were made from various materials such as gold, silver, bronze, jade, amber, agate, wood, and more. In terms of carving techniques, gold, silver, and bronze are typically cast, while amber and agate, being relatively softer, are easier to carve with a knife. Jade, on the other hand, is harder and much more challenging to sculpt compared to amber and agate.
The function of seals is not merely to stamp artworks; they are also used for identifying individuals. For instance, official government letters use official seals, personal correspondence has private seals, and racehorses are identified with animal seals. By the Five Dynasties and the Tang and Song Dynasties, the technique of making copper seals became popular, typically produced by casting rather than carving. During the Yuan Dynasty, the use of stone seals became prevalent. The forms of seals include circular, square, bas-relief, and intaglio. Materials used during the Song Dynasty included honey seals and water seals, with water seals being a mixture of ink and water, resulting in a thinner texture. Honey seals are made by mixing pigment with honey, giving a thicker and stickier consistency. The tactile feel of seals varies significantly with different types of paper and materials used. During the Song Dynasty, honey seals were less common, with most seals being water seals. It wasn’t until the Yuan Dynasty that a balance was achieved, with both water and honey seals being used, and later, honey seals evolved into oil seals, resulting in denser impressions that included a mixture of various minerals and plants.
Starting from the Ming Dynasty, chemical materials became more complex, and oil seals became widely used, facilitating easier color mixing, with the main colors being red combined with a hint of yellow.
In the Ming Dynasty, oil seals were classified into “thick, thin, deep, and light.” This kind of craftsmanship has its own nuances. Regardless of the material used for seals, such as jade or bronze, wear and tear inevitably occur with time. For instance, there may be surface blemishes or even fractures. Part of the authentication process for seals involves comparing the wear on the seal with that of other artworks. Different seals applied to various types of paper produce different effects, which is something to pay attention to during the appraisal of seals.
“Poetry, calligraphy, painting, and seals” are unique elements of Chinese culture. To create a perfect forgery, a seal is also an indispensable part. In addition to the common practice of manufacturing replica seals, some may also speculate and imagine seals based on pure conjecture. Another method involves metallurgical techniques, where after stamping, acid materials are used to erode the gaps. Finally, there are 3D laser seals, which can perfectly replicate even the smallest damage, but the downside is that they cannot fully reproduce the textural layers and colors of the original seal. These are also important considerations when authenticating artwork.