If your tee hems curl up, wave, roll under, or just look cheap on the rack, the fabric isn’t the whole problem. The hem is.

Jersey wants to curl. That’s physics, not a defect.

A finished tee looks finished because the hem construction fights that curl and wins.

Get the hem wrong, and even a beautiful 220 gsm loopback reads like a market stall.

Get it right, and a plain 180 gsm tee hangs like money.

This is the definitive, floor-level guide to tee hem finishing.

We run these operations every day in Sialkot, so this is written from the machine side, not scraped off ten other blogs.

Here’s what it covers:

  • Why jersey curls at the edge the knit structure behind the whole problem.
  • Single-needle vs. double-needle vs. coverstitch: the core stitch choice and which survives the wash.
  • Hem depth and fabric weight: how a hem is made to hang flat.
  • Raw, rolled, and lettuce edges the “unfinished” finishes that are actually design choices.
  • Blind hems and premium finishes the detailing that reads expensive.
  • Stabilizing lightweight jersey: the direct fix for curl and wave.
  • Matching hem to fabric and style the combined decision.
  • Specing the hem in your tech pack is the action step that locks it in so the factory can’t drift.

Read it top to bottom the first time. After that, jump to the chapter you need.

HEM-01

Why Jersey Curls at the Edge: the Knit Structure Behind Your Hem Problem

Before you can stop the curl, you have to know why it happens.

Almost every hem complaint traces back to one thing: a single jersey is an unbalanced knit.

Fix your understanding here, and the rest of the guide clicks into place.

A single jersey is one-sided by design:

Look at any tee body fabric. One face shows the smooth “V” columns (the loop legs).

The back shows the bumpy horizontal arcs.

The face and back are structurally different. That imbalance is baked into the loop.

A cut edge relieves that imbalance by rolling:

Inside a full panel, every loop is held in tension by its neighbors, so the fabric lies flat.

Cut the edge, and those loops have nothing pulling back.

They relax, and the fastest way to relax is to curl toward the side with less resistance.

The two axes curl in opposite directions; that’s your tell

On most single jersey, the crosswise edges (top and bottom, where your hem lives) tend to roll toward the face, while the vertical side edges roll toward the back.

You can confirm the exact direction on your own in ten seconds.

Balanced knits don’t curl, which is why ribbed hems exist

Interlock and rib are double-knit and symmetrical, so they lie flat off the cut.

That’s the whole reason cuffs, collars, and waistbands are ribbed.

A tee hem doesn’t get that luxury; it’s a single jersey, so the construction has to do what a balanced knit does for free.

What makes curl worse (so you can predict it):

  • Lighter GSM. Sub-160 gsm curls hardest with less fabric, less resistance. See lightweight jersey / fabric weight.
  • Finer gauge, tighter tension. More stored tension = more spring at the edge.
  • High-twist yarn. Twist is stored energy; it rotates the loop.
  • Under-relaxed fabric. Straight from finishing to cutting = curl and later shrinkage. Two problems, one cause.

The takeaway:

Curl isn’t the fabric being bad. It’s the fabric being a single jersey. Your hem’s job is to add enough structure, weight, and stitching to override that natural roll, and everything in the next seven chapters is a way of doing exactly that.

HEM-02

Single-Needle vs. Double-Needle vs. Coverstitch: The Hem That Survives the Wash

This is the core decision.

Get the stitch wrong and the hem either looks cheap or physically pops on the first stretch.

Here’s the honest breakdown of the three you’ll actually spec, including the one detail most blogs get wrong.

Single-needle: one line of stitching

A single row of topstitch, usually a lockstitch ISO 301. Clean, minimal, one thin line on the face.

  • The problem with knits: the lockstitch barely stretches. Pull the hem; the fabric gives and the thread doesn’t, so it snaps.
  • Where it works: stable, heavier fabrics, or an intentional minimal look. Not your default for stretchy jerseys.
  • Curl control: weakest. One line does little to hold a curling edge down.

Double-needle: two parallel lines on the face

This is what most people picture as a “proper tee hem”: two neat parallel rows.

The detail everyone misses:

On a knit tee, a “double-needle hem” is almost always made on a coverstitch machine with two needles on top and a looper thread interlooping underneath.

That looper is what gives the hem its stretch. A true two-needle lockstitch (the denim kind) does not stretch and will pop on jersey.

So when you say “double-needle,” make sure your factory means coverstitch. This one clarification prevents a lot of returned goods.

Coverstitch: the stitch class, not just a look

Coverstitch is the family that produces the durable, stretchy knit hem:

Two or three parallel needle rows on the face, a looper covering the raw edge underneath, and stretching with the fabric.

  • 2-needle coverstitch ISO 406: the standard tee hem.
  • 3-needle coverstitch ISO 407: wider coverage, activewear, and heavier-duty hems.
  • Top-and-bottom cover ISO 605: cover threads on both faces flat, sporty, and premium athletic in look.
  • Why it wins: it stretches and recovers with the jersey, so it survives wash and pull without popping.

Quick decision:

  • Everyday, stretchy, needs to last → 2-needle coverstitch (406).
  • Athletic / wider flat look → 3-needle or top-and-bottom cover.
  • Intentional minimal, stable fabric only → single-needle, eyes open on the risk.
HEM-03

Hem Depth and Fabric Weight: How to Make a Hem Hang Flat

Two tees can use the exact same coverstitch, and one still looks premium while the other flutters.

The difference is usually hem depth and how it plays with fabric weight.

This is the cheapest upgrade you can make to a hem; it costs fabric, not machinery.

Hem depth (allowance) is how much you fold up:

Typical tee hem depth runs 3/4″ to 1 1/4″ (about 20-32 mm), with 1″ (25 mm) as the safe default.

Too shallow → flimsy, curls more, reads cheap. Too deep → bulky, wastes fabric, and on heavy cloth it can flout.

Heavier hems hang flatter: this is the trick

A deeper fold puts more fabric weight at the very bottom edge. That weight pulls the hem down and counteracts the upward curl. It’s why a good heavyweight tee seems to “drop” cleanly and a cheap light one waves. You can buy flatness with hem depth.

Match depth to fabric weight:

  • Lightweight (≤160 gsm): go slightly deeper (up to ~1-1/4″) to add the weight the fabric lacks paired with stabilizing (HEM-06). 
  • Standard (170-200 gsm): 1″ is the sweet spot.
  • Heavyweight (210 gsm+): 1″ to 1 1/4″ hangs beautifully; don’t over-deepen, or the fold gets bulky at the side seams.

The needle gauge has to match the fold:

The coverstitch needle spacing (e.g., 3/64″, 1/4″) must sit within the hem allowance so both rows catch the folded edge cleanly.

Wrong gauge for the depth: one row missing the fold or an unbalanced hem.

Consistency around the sweep is non-negotiable:

A hem that’s 25mm at the front and 20mm at the side seam looks wonky even if nothing else is wrong.

This is a floor-control and marking issue, not a design one.

Bottom-hem consistency separates a real factory from a job shop.

HEM-04

Raw, Rolled, and Lettuce Edges: When “Unfinished” Is a Design Choice

Not every tee wants a clean coverstitch.

Streetwear especially plays with edges that look unfinished on purpose.

The line between “designed” and “sloppy” is intentionality plus a little hidden construction.

Here’s how to do the three most common ones right.

Raw edge: the deliberate unfinished hem

The cut edge is left unhemmed, allowed to curl and fray slightly.

Big in distressed and boxy streetwear.

  • Make it look designed: use it on heavier fabric that curls less and frays cleanly, keep the cut line dead straight, and often garment-dye afterward so the edge relaxes into a soft, uniform roll.
  • Optional hidden control: a single stay pass or a garment wash locks the curl at a consistent amount so every unit matches. Raw ≠ random.

Rolled hem: a narrow, tucked edge

A very thin rolled-under edge, made on a rolled-hem overlock or a rolled-hem foot.

Best for light fabrics where a full coverstitch adds too much bulk, or for a softer, more delicate finish.

Lettuce edge: the wavy, ruffled finish

An overlock (merrow) stitch is sewn while stretching the fabric, so the edge ripples like a lettuce leaf.

Retro / Y2K signature. The fabric is stretched under the overlock (or run with heavy differential feed), so it can’t recover flat.

  • Spec note: the amount of wave depends on stretch tension, so it must be sampled and sealed, or every unit waves differently.

The rule:

These are design decisions, not defaults, and not fixes for a hem you couldn’t finish cleanly.

If the brand aesthetic calls for it, own it and control it. If it doesn’t, don’t let “raw” become an excuse for a bad edge.

HEM-05

Blind Hems and Clean Premium Finishes: the Detailing That Reads Expensive

“Premium” at the hem is rarely an exotic technique.

It’s usually a cleaner version of a normal one, executed with more discipline.

But a few finishes are genuinely elevated.

Use this chapter when the brief says “elevated,” “luxury,” or “clean.”

Blind hem: the nearly invisible finish

A blindstitch machine catches only a thread or two of the outer fabric, so almost no stitching shows on the face.

  • The look: premium, tailored, quiet, with no topstitch lines interrupting the fabric.
  • The trade-off: less stretch and durability than coverstitch, slower and more skilled, finicky on very light or stretchy jersey. Reserve it for heavier, stable premium tees.

Bonded / fused hems: no stitching at all

A heat-activated film fuses the hem instead of sewing it.

Ultra-clean, no needle holes, very modern/athletic.

The trade-off: it needs the right fabric and equipment, and a cheap bond can delaminate in the wash.

Sample the wash test before you commit.

Most “premium” is just executional discipline:

  • Matched thread to the fabric color (or a deliberate contrast, never an accident).
  • Even, correct SPI with no loose, sloppy, or crowded stitching.
  • Zero skipped stitches and clean tension top and bottom.
  • Pressed hem: A steamed hem lies flat and looks twice the price of an unpressed one.
  • Consistent depth all the way around (back to HEM-03).

The honest truth:

A standard 2-needle coverstitch, matched thread, right depth, no skips, and pressed that already outclasses most of the market. You often don’t need a fancier stitch. You need a cleaner one.

HEM-06

Stabilizing Hems on Lightweight Jersey: Killing the Curl and Wave for Good

This is the chapter that solves the complaint that brought most people here:

The hem that curls up or waves and flutes on a thin tee.

Lightweight jersey is the hardest case to control the hem here, and you can control it anywhere.

Why is light fabric the worst offender?

The sub-160 gsm jersey has the least weight to resist curl (HEM-01) and the least body to resist the stretch of sewing itself, so it comes off the coverstitch wavy and fluted.

Two failure modes on one edge: it curls, and it ripples.

Fix 1: Relax the fabric before you cut

The single most underrated step. Let the fabric rest and relax off-tension before cutting and sewing.

Under-relaxed jersey curls harder and distorts after wash. Free to do, expensive to skip.

Fix 2: Fusible hem tape/stay tape in the fold

A narrow strip of fusible stabilizer ironed into the hem allowance adds body, kills the curl, and stops the wave.

The pro fix for thin tees, and it’s cheap. Match the tape weight to the fabric; it is too heavy, and the hem goes boardy.

Fix 3: Stop the machine from stretching the hem

  • Correct differential feed so the fabric isn’t pulled through.
  • Lighter presser-foot pressure on thin cloth.
  • Right needle: ballpoint / stretch, correct size, so you’re not punching holes or snagging loops.
  • Wooly nylon in the looper for soft, stretchy coverage that recovers instead of locking the wave in.

Fix 4: Add weight with depth

A slightly deeper hem (HEM-03) adds the weight; thin fabric is missing, which flattens the curl.

Depth and stabilizer together do most of the work.

The stack that works on 150 gsm:

Relax the fabric → fusible stay tape in the fold → ballpoint needle + wooly nylon looper → tuned differential feed → ~1-1/4″ depth → press.

That combination turns a curling, waving mess into a flat hem.

HEM-07

Matching Hem to Fabric and Style: the Combined Spec Decision

Every previous chapter was one variable.

Real spec’ing is combining them: fabric weight × knit type × brand aesthetic × price point → one hem decision.

This is the cheat sheet that ties them together.

The four inputs, in order:

  • Fabric weight sets how much curl you’re fighting and how deep the hem should be.
  • Knit-type single jersey needs the most help; heavier knits need less.
  • Aesthetic clean/premium, sporty, or distressed streetwear.
  • Price point decides whether blind hems, extra stabilizing, and slower ops are affordable.
Tee type Hem call
Lightweight fashion (140-160 gsm) 2-needle coverstitch + fusible stay tape, ~1-1/4″ depth. Or a deliberate rolled edge. Never a bare single needle.
Standard everyday (170-200 gsm) 2-needle coverstitch, 1″ depth, matched thread. The reliable default is not to overthink it.
Heavyweight boxy (210-260 gsm) Coverstitch at 1–1/4″; the weight does half the work. A blind hem here reads genuinely premium.
Distressed / vintage Intentional raw edge on heavier fabric, or a lettuce edge controlled and sealed (HEM-04).
Athletic / performance 3-needle or top-and-bottom cover for the flat look and extra durability.

Consistency across the garment:

Sleeve hems and the bottom hem should use the same stitch and read as one system.

And the hem should agree with the neck: a ribbed neck with a lettuce hem is a statement. Make sure you meant it.

The judgment call:

When two options both work, pick the one your floor executes most consistently at volume.

A slightly simpler hem sewn perfectly beats a fancier hem sewn unevenly across 500 units. Consistency is the premium signal.

HEM-08

Spec’ing the Hem in Your Tech Pack: The Step That Locks It In

You can know all of this and still get a bad hem if the tech pack is vague.

The factory builds what’s written, not what you pictured.

This is the action step: write the hem so precisely there’s nothing to drift.

Do it flat, and lasting hems become repeatable instead of lucky.

Put every one of these on the tech pack:

  • Stitch class + machine: Name the ISO class, e.g., 2-needle coverstitch, ISO 406. Don’t just write “double-needle”; that’s the phrase that gets you a lockstitch by mistake (HEM-02).
  • SPI (stitches per inch): 10-12 SPI controls look and strengthen.
  • Hem depth / allowance + tolerance, e.g., 25 mm (1″), ±2 mm.
  • Needle spacing / gauge: 3/64″ or 1/4″, matched to depth.
  • Thread and looper thread: Color, type, and wooly nylon in the looper if specified.
  • Needle type: Ballpoint / stretch, size.
  • Stabilizer: Fusible tape type, width, placement if the fabric needs it (HEM-06).
  • Fabric handling note: Relaxation before cutting; differential feed to prevent wave.
  • Flat-sketch callout: A hem construction detail / section view, not a buried note.
  • Approved seal sample: A physical reference to the line matches the final word when writing and reality disagree.
  • QC tolerance: Hem-depth consistency around the sweep, zero skipped stitches, and a stretch-and-recover check.

ISO shortcuts worth memorising:

  • 301 lockstitch (single needle; low stretch)
  • 401 chain stitch
  • 406 2-needle bottom coverstitch your standard tee hem
  • 407 3-needle bottom coverstitch
  • 605 top-and-bottom cover / flatseam

Writing 406, 11 SPI, and 25 mm leaves nothing to interpret. That’s the whole point.

Seal it, then hold to it:

The tech pack sets the target; the sealed sample proves it’s achievable; QC keeps every unit on it.

That’s how a flat hem stops being a one-off and becomes your house standard.

Hem FAQ

A single jersey is an unbalanced knit, so any cut edge naturally rolls.

Washing relaxes the fabric further and exposes it if the hem wasn’t stabilized.

The fix is a proper coverstitch, enough hem depth to add weight, and fusible stay tape on lighter fabrics.

Under-relaxed fabric makes it worse, so relaxation before cutting matters too.

On a knit tee they’re usually the same operation: a “double-needle” tee hem is made on a coverstitch machine, with a looper underneath that lets it stretch.

The danger is a two-needle lockstitch (the denim kind), which doesn’t stretch and pops on jersey. Always confirm your factory means coverstitch.

Around 1″ (25mm) is the safe default. Go slightly deeper (up to 1 1/4″) on lightweight fabric to add weight that helps it hang flat, and keep it moderate on heavyweight so the fold doesn’t get bulky.

Consistency around the whole sweep matters more than the exact number.

Wave comes from the fabric stretching as it feeds.

Relax the fabric before cutting, iron a fusible stay tape into the hem fold, use a ballpoint needle with wooly nylon in the looper, and tune the differential feed and presser pressure so the hem isn’t pulled through.

Slightly deeper depth adds flattening weight.

Name the ISO stitch class (e.g., 406), SPI, hem depth with tolerance, needle spacing, thread and looper thread, needle type, any stabilizer, and a fabric-relaxation note, plus a flat-sketch callout and an approved seal sample.

Writing “406, 11 SPI, 25 mm ± 2 mm” leaves nothing open to interpretation.

From the T-shirt manual

This is one chapter of The Complete T-Shirt Manufacturing Guides:

These chapters cover taking a T-shirt brand from idea to shipped units, costing, sourcing, tech packs, QC, freight, and launch comparisons. All written from the Sialkot factory floor of Gibben Clothing.

Open The Full T-Shirt Guides

On the floor · Sialkot

Written by

Faizan Ahmad

Chief Apparel Technologist & Head of Manufacturing, Gibben Clothing · Sialkot, Pakistan

Faizan leads production at Gibben Clothing, a cut-and-sew streetwear manufacturer in Sialkot, with 8+ years turning raw yarn into retail-ready hoodies, tees, bottoms, jackets, tracksuits, and headwear. He doesn’t just write about clothing; he works the floor, so every guide here is grounded in real fabric behavior, QC standards, and production data from live runs.