Pumps, viscosity and dip tubes

The mechanism

Foamer, lotion pump, disc top or flip top. Foamers need a thin liquid, lotion pumps tolerate a wide range, disc tops suit anything squeezable and flip tops suit a controlled pour. The product decides, and for a foamer the dispenser decides back.

The viscosity range

Published for a pump and routinely ignored. A product outside it doses inconsistently, which the customer experiences as a bottle that sometimes gives too much and sometimes nothing. Measuring viscosity rather than judging it is what makes this reproducible.

The dip tube

Cut to the bottle height so it reaches the base without kinking. It is the specification most often carried over when a bottle size changes, and the result is either a bottle that cannot be emptied or a tube bent against the bottom.

Output per stroke is a product decision

A generous dose feels luxurious and empties the bottle faster; a small one lasts and can feel mean. For a dish soap that is about how much goes into a sink, and for a hand soap about whether one press is enough.

Venting matters for squeeze bottles

A bottle squeezed hard and released draws air back in, and if it cannot the bottle stays collapsed. Wall thickness and the closure both affect it, and a bottle that will not recover its shape is one customers dislike immediately.

Test the assembled unit

Real formula, real bottle, real closure, used through a whole container including the last doses. Every failure on the previous pages shows up in that one test and almost none of them shows on a bench.

References