Bulb dipping

Bulb molds being dipped in latex during the manufacturing process.

A bulb mold is a balloon mold which is smoothly spherical or oblate, and which narrows through the neck and lip. Bulb-molded balloons, when fully inflated, have a shape resembling an incandescent light bulb.


Three bulbs

Three uninflated bulb-molded balloons. From left to right: Unique 12, Tuf-Tex 11, and Qualatex 11.

Nearly every round balloon 16" in size and smaller is made on a bulb mold. By contrast, most balloons 17" and larger manufactured in the United States are made on fluted molds. Notable exceptions to this are the bulb-molded Qualatex 18- and 24-inch balloons.

As the picture at left illustrates, bulb-molded balloons may still vary in shape; the notable differences are the body-to-neck diameter ratio and the severity of the body-neck transition. The Unique 12 has a wider body and narrower neck than the decorator Qualatex and Tuf-Tex alongside it, which both gives it a larger rated size (12" compared to 11") and gives it a "bumpier" neck when inflated.