Eobo Through Records and Analysis

Symbolizing the royal authority of Joseon and position of the royal family, the eobo (御寶) is a royal seal used in royal successions, honorific name creations or changes, and posthumous granting of honorific titles. 

It consists of a square block (보신, 寶身; body)

with an engraved surface and top (보뉴, 寶鈕; handle) decorated with a sculpted figurine.

Eobo are categories depending on the material, whether gold, silver, or jade.

At a glance, an eobo may appear to be made entirely of the outer material. However, analysis is required to verify the actual construction. When historical records written at the time of creation are examined and eobo are analyzed using modern equipment, certain truths emerge that were previously hidden to the naked eye.
The Annals of the Joseon Dynasty (조선왕조실록, 朝鮮王朝實錄) as well as other archives and manuals contain records of the entire production process of eobo.

The Annals of the Joseon Dynasty (조선왕조실록, 朝鮮王朝實錄) as well as other archives and manuals contain records of the entire production process of eobo.

Among them, the Records of the Supervising Office for the Funeral of Queen Consort Jangnyeol (장렬왕후국장도감의궤, 莊烈王后國葬都監儀軌; 1689) contains details regarding the materials, size, and weight of the Injobi Golden Eobo of Queen Consort Jangnyeol (인조비장렬왕후금보,仁祖妃莊烈王后金寶).

To confirm this data, the National Palace Museum of Korea used X-ray fluorescence (XRF) spectroscopy to analyze the materials used in the eobo. Non-destructive XRF analysis was selected to analyze the eobo without causing damage to the artifact.

As a result of the composition analysis, gold (Au) accounted for a high percentage at about 80%, and smaller amounts of copper (Cu), silver (Ag), zinc (Zn), and mercury (Hg) were detected. Although limited to surface analysis due to the characteristics of the analytical equipment, an assumption can be made that the core base metal is brass based on the detection of copper (Cu) and zinc (Zn).