Lining Fabric Choices: Moisture Transfer and Skin Comfort
The lining is the layer nobody discusses and the layer the wearer feels most. It sits against skin for the whole workout, it decides whether sweat moves away or stays, and it is often the difference between a bra that feels cool on a rowing machine and one that feels damp by minute ten. Choosing it by price, or letting the mill choose it by habit, is a common and expensive shortcut.
What the lining actually has to do
A lining in a medium impact bra usually has two or three jobs at once: add containment under the cup, provide opacity in pale shades, form the pocket for a removable pad, and manage moisture next to skin. Those pull in different directions. A high-power mesh adds containment but does little for comfort. A soft brushed tricot feels good but adds no support. Decide which job is primary, and let the second requirement be a separate component rather than asking one fabric to do everything badly.
Fibre choice drives moisture behaviour
Polyester is hydrophobic and holds almost no water, so a polyester lining next to skin moves liquid quickly and dries fast, which suits high-sweat sessions such as spin and rowing. Nylon absorbs around 4 percent moisture, feels less clammy at first contact but dries more slowly. The classic push-pull solution is a hydrophobic inner face against skin with a hydrophilic outer layer, so moisture is transferred outward rather than held. Viscose and bamboo-derived fibres absorb well and feel cool but lose strength when wet and dry slowly, so treat them as a comfort option for low-impact styles rather than for medium impact training.
Test the assembly, not the swatch
Wicking tested on the lining alone will not predict what happens in the garment. Have the lab test the sewn or bonded shell-and-lining assembly to AATCC 195, which produces wetting time, absorption rate, maximum wetted radius and an overall moisture management capability grade, and request grade 3 to 4 as a minimum. Add AATCC 197 vertical wicking and AATCC 79 drop absorbency, and check air permeability to ISO 9237 on the composite, because a dense lining can cancel the benefit of a ventilated cut-out back if it sits directly behind it.
Skin comfort and compliance
Comfort is partly chemistry. Hold the lining to OEKO-TEX STANDARD 100 product class II, with pH between 4.0 and 7.5 measured to ISO 3071 and free formaldehyde below 75 ppm measured to ISO 14184-1. Construction matters just as much: flat seams reduce chafe in the underband and side wing, and the pad pocket should use a low-friction lining so a removable pad slides in and out without dragging. Where the bra closes with a hook at the back, keep the lining clear of the hardware area so there is no bulk between the fastener and the skin.
Matching properties with the shell
The lining must move at the same rate as the shell. Require both to sit inside the same plus or minus 3 percent dimensional change window to AATCC 135 after five washes, or the cup will pucker and the edge of a cut-out panel will wave. Check bursting strength to ISO 13938-1 on open linings and seam strength to ISO 13935-2 on the shell-to-lining join, then inspect to ANSI/ASQ Z1.4 at AQL 2.5.
Choose the lining for its primary job, test the assembly rather than the swatch, and match its shrinkage to the shell. Do that, and comfort complaints fall without touching the shell specification at all.
