The heat-resistant lower edge of a hot-air balloon’s envelope, near the burner flame, is called the skirt.
The skirt hangs below the main fabric envelope and surrounds the mouth, where heated air enters. It is made from heat-resistant material to protect the balloon fabric from the burner’s flame and hot exhaust. The skirt also helps guide the rising hot air into the envelope during inflation.
The skirt should not be confused with the envelope’s crown or parachute valve. The crown is the top area of the envelope, while the parachute valve is a controllable opening used to release hot air during descent. “Gore” has a different meaning: it is one vertical fabric section making up the envelope.
During inflation, crews often hold the skirt open while the burner fills the envelope. Once the balloon is upright and buoyant, the skirt remains a visible protective transition between the burner system and the fabric body.