Leakproof Period Pants

Barrier design

Leakage in menstrual pants happens through three paths:

• Leg-cuff gap. The most common leak path. Caused by elastic tension that is too low, a chassis that is too narrow for the user's thigh, or movement that pulls the cuff away from skin.
• Rear overflow. Fluid travels along the backsheet and exits at the waistband. A longer chassis, wider rear core and hydrophobic waistband barrier reduce this.
• Side compression. When the user lies on their side, fluid can be squeezed out of the core laterally. A firm core wrap and side barriers prevent this.

Barrier materials

• Standing cuffs. Hydrophobic SMS nonwoven, 15–20 gsm, with two strands of spandex elastic. The cuff must stand at least 20 mm above the topsheet when relaxed.
• Backsheet. Impermeable PE film, 20–30 gsm, laminated to a soft nonwoven for comfort. Breathable film is acceptable only if the MVTR does not compromise liquid barrier performance.
• Core wrap. Tissue or hydrophilic nonwoven that contains SAP and pulp even when saturated. A poor wrap lets SAP escape through the leg openings.

Validation tests

Ask suppliers for the following test data:

• Rewet test. Measures how much fluid returns to the surface under pressure. Lower is better for skin health and leak confidence.
• Edge-leak test. A tilted or side-lying mannequin test that simulates nocturnal leakage paths.
• Strike-through and run-off. How quickly fluid enters the core and how much runs off the surface before entry. Fast strike-through reduces side pooling.

What to specify

• Standing-cuff height, material and elastic tension
• Backsheet type and thickness
• Core-wrap basis weight and wet-strength requirement
• Rewet and edge-leak test methods with acceptance limits
• Fit-test protocol on your target size curve

Where leakproof products fail in use

• Seam wicking. Liquid travels along the seam thread from the core to the outer edge. Ask for the seam seal method and the thread type.
• Cuff inversion. Cuffs fold outward and channel fluid straight to the leg opening. Ask for cuff height and how the cuff is anchored.
• Strike-through at the core edge. A core narrower than the pad outline leaves a wet margin. Ask for the core-to-edge margin per size.
• "Leakproof" with no test behind it. The word needs a defined test, usually hydrostatic head or strike-through under load. Ask for the figure and the method.

Writing the RFQ line

Leakproof is a test result, not a product feature. State:

• The barrier definition you will accept: hydrostatic head value, or strike-through under a stated load
• Seam seal method and thread type
• Standing cuff height and anchoring
• Core-to-edge margin per size
• Whether the product must hold under a lying-down protocol as well as a sitting one

What a leak test cannot tell you

A pass on a standard test does not mean the product will not leak in use. Three limits are worth knowing before you accept a report:

• The test posture is fixed; the user is not. Most lab protocols hold the sample in one position. A sleeping user changes position many times a night, and most side leakage happens during the turn, not while still.
• Hydrostatic head measures film, not openings. It tells you the backsheet resists water pressure. It says nothing about the leg opening, which is where the fluid actually escapes. A product can pass a very high hydrostatic head and still leak at the cuff.
• Capacity is not containment. Two products with the same millilitre figure can behave very differently at the edge. If a supplier only sends a capacity number, you have not been told anything about leakage.

Write the test condition down, not just the result: posture, volume, dosing rate, load applied and duration. A figure without those four is not comparable between suppliers, and it will not survive a retail customer asking how the claim was substantiated.