Mr Chai was explaining and demonstrating seal engraving.
Seal engraving is a unique art form of Chinese characters which has more than two thousand years of history and went through dozen dynasties. Artists, scholars, collectors and intellectuals possess their personal seals. Seals can be divided into :
Name seals - Denotes the person's name.
Leisure seals - are the equivalent of today's email signature, and can contain the person's personal philosophy or literary inclination. These can be any shape, ranging from ovals to dragon-shaped.