Han dynasty officials often carried seals with them to seal documents while on official business. These were usually diecast in metal, but in an emergency they could be carved directly into other material, making what became known as an "emergency seal."
漢時官吏為行使職權，經常得把印信帶在身上作簡牘封泥之用，印章則多用澆鑄法鑄造，但如遇軍中緊急須用，不及澆鑄，就用刀直接在印材上鑿刻，後世稱為鑿印或「急就章」。