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A mascara wiper lip may open as the brush passes through and then move back toward its resting shape. For a buyer, the useful comparison is the shape it reaches after a defined wait and whether that result changes after repeated passes.

Measure the installed lip

Seat each wiper in a production-representative neck. Take a baseline image of its opening with a scale, steady lighting, and a camera aligned with the opening. Keep the brush, stem, withdrawal direction, speed, and depth the same. If the test includes filled packs, use the same formula and conditioning. Prepare separate samples for a clean bench comparison and for formula contact where both are useful.

After the selected number of passes, photograph the lip at the same intervals for every sample. Record changes in opening size or shape, uneven edges, and any movement of the whole insert. A lip that looks open just after withdrawal may recover during the wait. A tilted or lifted insert needs a separate retention check. Inspect the lip without cleaning it first if cleaning could change the measurement, and use a separate sample for a clearer view when residue hides the edge.

Compare the images with the baseline and with an uncycled sample. Report the brush geometry, number of passes, and wait times with the results. If shape change coincides with a change in product pickup, measure pickup under controlled conditions in a separate check. Closure integrity also needs its own assessment on the filled pack. The recovery test gives you a way to compare the lip response without assigning a cause to every change in use. The SamBound packaging catalog is available at sambound.com.

sambound.com
SamBound New Material Technology Company Ltd.

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