Method for manufacturing glass panel unit

A method for manufacturing a glass panel unit, the method comprising:

• a glue arrangement step including arranging a hot glue on either a first panel or a second panel, the first panel including a first glass pane, the second panel including a second glass pane;
• an assembly forming step including forming an assembly including the first panel, the second panel, and the hot glue and having an exhaust port provided through at least one of the first panel, the second panel, or the hot glue by arranging the second panel such that the second panel faces the first panel;
• a first melting step including heating the assembly to melt the hot glue, bonding the first panel and the second panel together with the hot glue thus melted, and thereby forming an internal space surrounded, except the exhaust port, with the first panel, the second panel, and the hot glue melted;
• an evacuation step including reducing pressure in the internal space by evacuation that involves exhausting a gas from the internal space via the exhaust port;
• and
• a second melting step including creating a hermetically sealed evacuated space by heating the assembly and thereby melting the hot glue while maintaining a reduced pressure in the internal space to close the exhaust port and seal the internal space up,
• the first melting step including:
• a temperature raising step including raising a temperature of the assembly to a temperature equal to or higher than a softening point of the hot glue;
• a temperature maintaining step including maintaining the temperature of the assembly at the temperature equal to or higher than the softening point;
• and
• a temperature lowering step including lowering the temperature of the assembly to a temperature less than the softening point,
• the temperature raising step, the temperature maintaining step, and the temperature lowering step being performed in this order,
• the temperature lowering step including:
• an anterior temperature lowering step including lowering the temperature of the assembly;
• a middle temperature maintaining step including maintaining the temperature of the assembly;
• and
• a posterior temperature lowering step including lowering the temperature of the assembly,
• the anterior temperature lowering step, the middle temperature maintaining step, and the posterior temperature lowering step being performed in this order.