Flounce can also refer to technique used in dress making:
NOUN:
A strip of decorative, usually gathered or pleated material attached by one
edge, as on a garment or curtain.

Perhaps such sewed places might be damaged by dry cleaning or laundering, as stitches might break, and so some type of test might be appropriate.

Incidentally, this is similar to two meanings of "cleave" in another thread. The dictionary gives two different etymologies for "flounce".