Fluted molds

A pair of four-flute molds.

A fluted mold is a balloon form which is designed to produce a perfectly spherical balloon by increasing the amount of latex available around the balloon's girth. Fluted molds have four (or sometimes six, eight, or more) waves, or flutes, running down the length of the balloon's body. Uninflated fluted balloons have a shape that can resemble a bell pepper.


Tuftex flutes

Perspective of an uninflated red Tuf-Tex 17. Note the four-fluted "X" shape.

Fluted molds are typically used to produce spherical balloons 17" in diameter and larger. Nearly every American-produced balloon sized 24" and larger uses a fluted mold (with the exception of the Qualatex 24). Punch ball balloons frequently use eight-flute molds.

Balloons produced on fluted molds typically inflate to a perfectly spherical shape, as opposed to the oblong teardrop shape of balloons produced on bulb molds. Body-neck transitions on fluted balloons are typically quite sharp, making fluted balloons typically very difficult to fully inflate into their necks.

Flute lines

Inflated Tuf-Tex 17, viewed from the drip point. Notice the flute lines.

During manufacturing, latex cohesion means fluted molds collect more latex in the "valleys" of the flutes. This creates a small thickness variation along the ridges of the flutes that is visible in the inflated balloon as flute lines, shown at left.
Qualatex 3 foot types C

The older 40 inch flat paddle version of the Qualatex giant and its 4 flute replacement just filled with air.

Here is an example of a pair of Qualatex balloons.  The flat paddle version of their giant in light blue and a red 36 inch fluted version that replaced it filled with just enough air to shape it but not start to inflate it.

Notice how boxy the fluted version seems at this point.  The stopper is an empty 35 mm plastic film can which is an ideal stopper for many of the larger necked balloons since it is light and has a rim.  The flat paddle balloon was said to be a 40 inch balloon and would inflate that large but it was suggested that 36 inches was closer to its rated size. Notice how fat the neck is on the paddle balloon to facilitate removal of the form and the rounded transition into the neck of the paddle balloon. The light blue grid is 1 inch.