halfballoon

A halfballoon is a hemispherical inflatable object produced by partially inflating a balloon to create a domed, half-sphere form. The term is used in decorative and educational contexts to describe a balloon that is inflated to a limited volume and secured along its rim to maintain a stable, curved cap rather than a fully extended balloon.

Construction typically uses latex or flexible polymer balloons, with the opening sealed around the rim to form a closed dome. The inflation level is controlled to produce approximately a hemisphere rather than a full sphere. Because the shape relies on the pressure of the contained gas, options include filling with ambient air, helium, or hot air, with buoyancy depending on the gas type and total volume.

Applications and variations: A halfballoon is used in classroom demonstrations to illustrate buoyancy, surface tension, and geometry. It is also featured in decorative displays and stage props, where multiple halfballoons can be arranged to form arches, lanterns, or sculptures. Some artists explore variants such as color-coated halves, translucent materials, or magnetic or weighted rims to attach to structures.

Limitations and safety: Limitations include susceptibility to punctures, dependence on volume for stability, and potential allergen concerns with latex. Storage should be cool and away from sharp objects. They are not intended for children under three without supervision.