Leggings Manufacturing Process

Leggings are a clear example of a garment where the fabric is the product. Two pairs cut from the same pattern in two different knits behave nothing alike: one holds, stays opaque and recovers, the other bags at the knee and goes translucent when the wearer bends. This page covers what to specify so you get the first one.

Fabric: composition, weight and the two properties that matter

Legging fabric is a circular or warp knit with elastane. Two properties decide whether it works, and neither is weight. Recovery is the fabric's ability to return to shape after being stretched, which is what stops knees bagging. Opacity under tension is whether the fabric stays opaque when it is stretched over the body, which is the complaint that ends programmes.

Pattern: negative ease and how to specify measurements

A legging pattern is cut smaller than the body it is meant to fit, so the fabric is under tension when worn. That is negative ease, and how much of it a pattern uses depends on the fabric's stretch and recovery. The consequence for a tech pack is simple: measurements must be stated in the relaxed state, flat and unstretched, or they cannot be checked consistently.

Rise is the other measurement that decides how leggings are received. High rise, mid rise and low rise are three different patterns rather than a styling note, and the rise interacts with the waistband construction. State it as a measurement rather than a description.

Panels: how many, and why

• Two-panel construction. A front and a back leg with inseam and side seams. The simplest and most economical.
• Side-seam-free construction. The leg is cut so there is no outside seam, which removes a line down the leg and a potential irritation point. It uses fabric differently and limits where panels can be placed.
• Panelled construction. Additional shaped panels at the side, back or leg. This is how contour and colour blocking are created, and each panel is another seam to sew and align.
• Contrast or mesh inserts. Ventilation or design panels at the knee, calf or thigh, often matched to a tracksuit or training set. Each insert is a separate fabric that has to be approved for both colour and stretch, since a low-stretch insert restricts the whole garment.

The gusset

Where the two inseams and the crotch seam meet, four layers of fabric intersect at the highest-stress point of the garment. A gusset, usually a diamond or triangular panel, replaces that intersection with a smoother junction.

It improves freedom of movement, reduces the chance of seam failure and removes a pressure point in wear. It costs one extra small panel and one extra operation. For anything intended to be trained in, specify it.

Seams: flatlock and why it is used

Seams on stretch garments have to extend with the fabric. A conventional lockstitch will break under extension, so leggings are sewn on stretch-capable machines.

• Flatlock. Joins two panels edge to edge with no seam allowance standing proud, producing a flat seam that does not rub. It is the standard for performance leggings worn against the skin.
• Overlock with coverstitch. A conventional overlocked seam with the allowance topstitched flat. Slightly more visible than flatlock and generally more economical.
• Needles and thread. Ballpoint needles are used so the knit loops are displaced rather than pierced, and thread has to be chosen for extension. Why that matters on a knit is set out in thread and needles. Skipped stitches and seam grin on elastane fabric usually trace back to these settings rather than to the operator.

The waistband

The waistband is a common source of complaints alongside opacity, and there are several constructions.

Roll-down at the waist is the failure to watch for. It comes from a combination of rise, waistband height, elastic choice and fabric recovery, and it is assessed on a worn sample rather than flat.

Decoration: what works on stretch

Decoration options are narrower here than on most garments in this section, because whatever is applied must stretch with the fabric.

• Sublimation. The usual option for all-over designs on polyester-based fabric, printed before cutting so the pattern runs across panels. It adds no layer and cannot crack. It is not suitable on polyamide.
• Transfer printing. Works for logos and small placements, using transfer systems with enough elasticity for the fabric. A rigid transfer on a stretch panel will crack.
• Silicone or elastic prints. Designed to extend with the fabric, and often used for logos on activewear.
• Embroidery. Generally avoided on the main stretch panels, because stitching restricts extension and distorts the knit. Where it is used, it is placed on a stabilised or non-stretch area.
• Printed labels rather than woven. Woven labels at the waistband are a common irritation point, so a printed label or a heat-applied one is normally specified instead.

Assembly sequence

1. 1Fabric is relaxed and spread without tension, since stretch fabric spread under tension produces panels that shrink back.
2. 2Panels are cut, with any contrast or mesh inserts kept in register.
3. 3Decoration is applied where the method requires flat fabric.
4. 4Panels are joined: inseams, side seams where present, and any shaped panels.
5. 5The gusset is set at the crotch intersection.
6. 6The waistband is assembled with its elastic, drawcord or pocket, then attached.
7. 7Hems are finished, usually coverstitched or left as a clean-cut edge on fabrics that do not fray.
8. 8Labels are applied, the garment is inspected and packed.

Quality control: leggings-specific checks

What to put in a leggings tech pack

• Fabric: composition with elastane percentage, structure, target weight, and required stretch and recovery behaviour.
• An explicit opacity requirement, stated as a check under stretch in the actual colour.
• Rise as a measurement, and the waistband construction with band height.
• Elastic specification where used: width, type and quality.
• Panel layout: two panel, no side seam, or panelled, with any inserts.
• Gusset: required, with shape and dimensions.
• Seam type per seam: flatlock, or overlock with coverstitch.
• Hem finish and leg length, including any cropped or 7/8 length.
• Measurements in the relaxed state with tolerances.
• Decoration method, artwork and placement, with confirmation that it will extend with the fabric.
• Label type, with printed labels specified where a woven label would irritate.

Sampling

Leggings must be sampled worn. Flat measurements confirm the pattern, but opacity, recovery, waistband roll-down and seam comfort can only be assessed on a body in movement. Ask for the sample in the actual bulk fabric, since a substitute knit with different elastane content tells you nothing useful.

Where the programme allows, wash and re-check the sample. Recovery after washing is what determines whether the garment still fits in three months, and it is cheap to test before bulk. The general stages are covered in the sampling guide.