Interlining is the layer that sits between the shell (outer fabric) and, when there is one, the lining. It is not lining. It is not wadding (the lofted fill in a quilt or puffer). Interlining is the skeleton: shape, support, crease resistance, reinforcement. Without it a collar collapses, a facings waves, a waistband rolls.
TrimGem samples fusible and sew-in interlinings as part of the accessories pack. The construction of the base cloth is the first decision. The adhesive is the second (next notes).
What the base is
GB/T 31903-type language splits apparel interlinings by base:
- Woven interlining — a woven base, usually then coated.
- Knitted interlining — a knitted base: weft-knit, weft-inserted warp-knit, biaxial warp-knit.
- Nonwoven interlining — a fibre web, chemically, thermally or mechanically bonded, then often coated. Includes some hot-melt film fusibles.
Sew-in haircloth (horsehair, “hair canvas,” mawei / charcoal canvas) still exists for tailoring. Chemical (fusible) interlining is the industrial default: a base plus a hot-melt (PA, PES, PE, and others).
Older encyclopaedias also split cotton canvas, linen canvas, haircloth and “chemical” fusibles. Useful historically. The mill SKU is woven / knit / nonwoven × sew-in / fusible × adhesive type.
Woven
The original support cloth: starch-stiffened cotton, then fusible-coated wovens. Plain weave is common; crepe, herringbone and twill appear. Strength and dimensional stability are the point. Belts, waistbands and tailored fronts that must not grow use woven. Hand is firmer. Cost is higher. Cheap casual shirts often skip it for a nonwoven.
Match colour and weight to the shell. A heavy flannel wants a heavier base; a silk wants a light one.
Knitted
Knits exist because wovens can feel boardy. A weft-insert warp-knit (the workhorse “knit fusible”) gives stretch in one direction, recovery, and a softer drape while keeping stability in the other. Fine textured filaments keep mass down. Price is higher. Suits, jackets and better womenswear pay it.
Weft-knits are used on wool and light shells; fusing temperatures in mill sheets often sit around 165–175 °C — always overridden by the adhesive’s window and a trial.
Stretch shells need stretch interlinings. A stable woven on a four-way stretch is a delamination waiting for the first lift of an arm.
Nonwoven
No yarn interlacing: viscose and polyester staple (and others) made into a web. Weights from about 10 g/m² to 200 g/m² and beyond. Light, soft or quite stiff, little grain, easy to cut in any direction. Shirt collars, cuffs, pocket mouths, plackets, and many facings on wool programs. White is the stock colour; dyeing exists.
Nonwovens are not “fake wovens.” They are the right article for small, stiff, cheap zones. They are the wrong article for a full coat front that must drape (see woven vs nonwoven).
How a mill writes the product
Marking examples (GB/T 31903 style) pack fibre, yarn count, density, width, gsm, weave, and the adhesive:
- Woven:
T/C 65/35 … 165 HDPE+PES-161 irregular— polyester/cotton, 165 g/m², mixed HDPE + PES powder, 161 dots/cm². - Nonwoven:
100%T … 17 PES-110 irregular— polyester, 17 g/m², PES, 110 dots/cm². - Film:
PES 60-120-50-140-005 film— copolyester film, thickness and melt midpoint named.
Adhesive codes you will live with: PES (copolyester), PA (copolyamide), TPU, EAA, EVA, HDPE / LDPE (polyethylene). The coating note explains how those dots get onto the cloth.
Spec line
Write woven / knitted / nonwoven, fibre, gsm, fusible or sew-in, adhesive family, and the garment zone. Pair the hand of the base to the shell. Pair the stretch to the shell. Interlining is not lining: lining slides; interlining shapes. It is not wadding: wadding lofts. Get those three words right and the rest of the series is details.