When you apply clear elastic or elastic to a fabric and it jams underneath, the stitch becomes irregular, or it bunches up, the cause is almost always the same: a tension problem with the upper thread, triggered during threading.

Even if you have threaded your machine 1,000 times, it only takes one wrong pass to cause this type of glitch.

1. The telltale sign: the needle thread is not taut

Before blaming everything (the clear elastic, the fabric, the machine, the stitch…), check this very simple point:

Gently pull on the needle thread.
If it comes out too easily, without clear resistance → the thread is not in the tension discs.

And if the upper thread is not properly tensioned, it no longer controls the clear elastic or the elastic.
Immediate result:

• jamming under the fabric,
• gathering,
• bunched-up zigzags,
• clear elastic that “slips back” while the fabric moves forward.

This is a key diagnostic.

2. Why it happens: the habit trap

When you know your machine by heart, you thread it mechanically.
The problem is that threading too quickly makes you miss THE essential step:

The path between the tension discs (usually just behind the adjustment dial).

If the thread doesn’t go properly between the discs, the machine sews… but without real tension.
On fabric alone, you might get away with it.
On clear elastic or elastic, it’s a guaranteed disaster.

3. The basic rule (that we forget because we’re in a hurry)

For tension to be applied correctly:

1. Always thread the machine with the presser foot up

Foot up = discs open → the thread can enter.
Foot down = discs closed → the thread stays outside → zero tension.

2. Take the time to push the thread into the discs

Never just “slide it in front.”
You push slightly until you feel the thread click into place.

3. Pass through every guide in order, without skipping any

Even one missed guide changes the final tension.

4. Check by pulling lightly on the thread at the end

• Clear resistance → active tension → OK.
• Thread too loose → re-thread → DO NOT sew.

These rules are not “for beginners.”
They are mandatory, even after twenty years of sewing.

4. Why clear elastic highlights everything

On normal fabric, imperfect tension can go unnoticed.
But on clear elastic (or regular elastic):

• rigid material,
• moves slower than the fabric,
• requires precise control of the upper thread.

As soon as the tension is low → the fabric moves, but the elastic doesn’t → this creates jams and bunching.

5. Summary

• If the needle thread is not taut, it is definitely a threading problem.
• The thread must pass between the tension discs with the foot up.
• Jams under the fabric with clear elastic or elastic almost always come from missing or poorly applied upper tension.
• Re-threading properly fixes 90% of cases.
• Even if you know your machine, you must follow the basic rules: foot up, discs open, thread pushed inside.

People talk about it a lot, often incorrectly. “This fabric is stretchy” doesn’t mean much on its own. You need to understand how, how much, and why.

What is a fabric’s stretch?

Stretch is a fabric’s ability to lengthen when you pull it, then return to its original shape.
It’s measured as a percentage. For example, if you have a 10 cm square of fabric that stretches to 12 cm when you pull it, it has 20% stretch.

But it’s not enough to have a fabric “that stretches.” Before you start, you should always check that its stretch matches what’s indicated on the pattern.
Most patterns specify a minimum (and sometimes maximum) stretch percentage. If you choose a less stretchy fabric, the garment may end up too small or uncomfortable. Too stretchy, and it can lose its shape or gape.

Stretch direction

Another essential point: stretch isn’t always the same in every direction.
Some fabrics stretch only horizontally (crosswise grain, perpendicular to the selvedge), while others stretch both ways, horizontally and vertically.

It changes everything. A bi-stretch knit (both directions) gives more ease and overall comfort, but it also means you need to anticipate how the garment will behave lengthwise (to avoid it “growing” and dropping too much, for example in a dress).

Why is it important?

If you don’t follow the stretch percentage and direction specified by the pattern, you risk:

• A garment that’s too tight—turning you into a roast.
• A neckline that gapes like a hammock.
• Length that stretches unexpectedly.

A pattern designed for a knit with 40% stretch and that stretches only in width won’t give the same result if you use a bi-stretch knit or a firmer jersey.

Stretch and comfort

Stretch makes garments more forgiving. It accommodates small body fluctuations and gives you ease without sacrificing the fit.
It’s also what keeps a T-shirt from stopping mid-bicep when you lift your arms, or a dress from riding up like a mini skirt as soon as you take a step.

Stretch and technique

Sewing stretchy fabric isn’t insurmountable. You need to:

• Use a stretch stitch (a narrow zigzag or lightning stitch).
• Don’t pull on the fabric as you sew, to avoid distortion.
• Stabilize certain sensitive areas (necklines, shoulders) with stay tape or thin elastic.

A serger is perfect for handling stretch. But a regular sewing machine is more than enough if you choose the right settings.

Common pitfalls

• Confusing stretch with drape: a drapey fabric may not be stretchy at all.
• Underestimating recovery: a fabric may stretch, but does it bounce back well? Poor elastic recovery leads to a garment that relaxes and loses its shape quickly.
• Ignoring direction: not identifying the main stretch direction can ruin the fit.

Dare to go stretchy

A lot of people avoid it, thinking it’s only for sporty styles or for serger pros. Not true.
Stretch is freedom: the freedom to move, live, breathe, and pull it over your head through the neckline—without an invisible zip, buttons, or any other fastener.

Ah, knits! The mere mention of the word is enough to scare off some sewists. “It slips, it stretches, it loses its shape…” We hear all sorts of conflicting things.
Yet, knit fabric is a powerful ally for anyone wanting to sew comfortable, modern, and wearable everyday clothes.
Before you close your drawer and run back to your poplin, take two minutes to understand what’s really behind the word.

Unlike woven fabrics, knits are—as the name suggests—knitted. The principle is the same as a sweater, but in a finer and often more fluid version.
Instead of crossing perpendicular threads, loops are formed, giving the fabric its famous elasticity. As a result, knit fabric hugs your curves, moves with your body, and offers unparalleled comfort.

In comparison, woven fabric is the classic choice: cotton, poplin, twill, satin… Here, the threads are crossed at right angles, resulting in a stiffer, more stable fabric. It’s perfect for shirts, structured jackets, or straight-leg trousers. But it’s also less forgiving: being off by just a centimeter, and you’ll quickly feel constricted.

Knit fabric, on the other hand, allows for some leeway. It forgives a minor cutting error or a slightly imprecise seam. Everyone has a knit t-shirt in their wardrobe—often not of great quality—that twists after a few washes or where the side seam ends up across the stomach.
When well-chosen and well-sewn, knit fabric is a joy to wear and to sew.

Jersey is undoubtedly the best-known knit fabric. It can be 100% cotton or blended with elastane or viscose for added stretch and drape. Lightweight and soft, it’s perfect for tops, casual dresses, or underwear.

Interlock is a double-sided jersey. It is made of two interlocking layers of knit, making it thicker and more stable than single jersey. It hardly curls at the edges, making it easier to cut and handle. It has a crisper, more structured drape. It’s used for dressier t-shirts, straight dresses, or cozy pajamas.

Milano knit is denser and more tightly knit. It retains the stretch inherent to knits while offering a more sophisticated look. It’s found in bodycon dresses, pencil or A-line skirts, and even unlined soft jackets. With it, you can achieve a “chic” style while remaining comfortable.

Finally, mesh is an openwork technical knit, widely used in lingerie, sportswear, or breathable panels. It offers transparency and lightness, allowing for layering and more technical or graphic effects.

Sewing knits also means adapting to their stretch. We often talk about the stretch percentage when choosing a suitable fabric: less than 20% for a more stable knit, around 20% to 40% for a classic t-shirt, and higher for leggings or lingerie. For sewing, a serger is the ideal machine: it assembles, finishes the edges, and maintains the fabric’s elasticity. However, a standard sewing machine can definitely do the job, provided you use a stretch stitch (a narrow zigzag or a lightning stitch).

You shouldn’t pull on the fabric while sewing, or you’ll end up with wavy necklines or rippled hems. It’s better to let the machine do the work!

Knit fabric isn’t just a technical material; it’s a state of mind. It invites flexibility, comfort, and freedom of movement. It allows you to make mistakes, to be bold, and to start over. Contrary to popular belief, it’s not a material reserved for “pros.” In fact, it’s an excellent teacher: it teaches you to listen to the fabric, anticipate movement, and accept imperfection.

Sewing knits means accepting that everything won’t always be perfect to the millimeter. And that’s what vibrant, creative sewing is all about. Knits are everywhere, already in our closets. They make you want to dive in, take a chance, and create clothes that move with you instead of restricting you.

So, why wait? Grab that jersey sitting in a drawer, get out your serger (or sewing machine), and give it a go. Even if the first attempt isn’t perfect, you’ll have learned something, and more importantly, you’ll have made progress.

Daring to sew with knits is about reconciling with your body, with movement, and with the idea that a garment isn’t armor, but an everyday companion.