How to Fix a Snag in a Heavy Hoodie

Heavy sweats come back into rotation in September, and within a fortnight somebody catches a loop on something. A backpack zip. A watch clasp. The hook side of a strip of velcro. A dog's claw on the way past. One second of contact and there is a long thread lying across a hoodie that was clean and flat an hour before.

A snag is not a hole. The difference decides whether the piece gets fixed in two minutes or wrecked in one, so it is worth knowing which is in front of you before the scissors come out.

What a snag actually is

A weft knit is one continuous yarn bent into loops, each loop held in place by the loops around it. A snag happens when something hooks under a loop and drags it out of the plane of the fabric. In most cases the yarn is still whole. What has moved is length. The pulled loop borrowed slack from the stitches on either side of it, which is why a snag comes with a raised thread in the middle and a tight, puckered patch running out from it in both directions.

Textile labs treat snagging as a measurable property rather than bad luck. ASTM International publishes two test methods for it. ASTM D3939/D3939M-13(2017), Standard Test Method for Snagging Resistance of Fabrics (Mace), works a spiked head against fabric fitted over a drum. ASTM D5362-13(2018), Standard Test Method for Snagging Resistance of Fabrics (Bean Bag), makes the fabric into a cover over a bean bag and tumbles it in a chamber lined with pins. Both count the snags that result, and D5362 says the count should be read alongside appearance factors such as colour contrast, distortion and how far the snag protrudes.

Both standards are also honest about their limits, which is the useful part. D3939 states that it is not considered satisfactory for acceptance testing of commercial shipments because between-laboratory precision is poor. D5362 states that its precision is acceptable for that purpose. And neither method is written for the cloth in a heavy hoodie: both scopes exclude very heavy or very stiff fabrics, the ones that cannot be fitted tightly to the drum or made into a bag cover, along with open constructions, tufted fabrics and nonwovens.

Why sweatshirt cloth catches more than a T-shirt

Loopback terry carries a face of flat jersey and a back full of loops standing proud of the ground. Brushed fleece is the same structure with those loops cut open and combed into a nap. Either way, the inside face of a sweatshirt is a field of raised yarn, and a hook only has to get under one of them. Single jersey in a T-shirt has less to offer a zip tooth.

Weight cuts both ways. Heavier yarn and a tighter stitch resist being plucked out, but a heavy loop, once pulled, drags more length with it, so the pucker is longer than it would be on a thin knit.

The first rule is do not cut it

Cutting a snag flush is the common instinct, and it turns a displaced loop into two cut yarn ends. Cotton Incorporated's technical bulletin Guide to Evaluating and Reducing Holes in Knitted Fabrics is written for mills rather than wearers, but its list of causes makes the point plainly. Holes in knits come from mechanical damage: fabric snagged on sharp burrs on trucks, spreaders and rolls during processing, needle cutting during garment assembly around seams, yarn broken by excessive tension at the machine. A knit hole starts as a cut or broken yarn far more often than it starts as worn-out cloth.

Whether a cut loop then runs is not something to be confident about. It depends on the structure, the stitch tension and where the cut sits. On a dense heavy knit a snipped loop may sit still for months and then open up in a wash. Nobody publishes a clean number for that, and anyone who tells you a cut snag is always fine, or always ladders, is guessing. The safe move is to keep the yarn in one piece.

Working the snag back in

This part is workshop practice rather than tested method. It works, it is reversible, and it takes a couple of minutes.

Take the hoodie off before doing anything. Pulling a garment over your head with a snag in it drags more length through.
Turn it inside out and find both ends of the pull. Follow the tight, puckered line running away from the raised thread. That line shows where the borrowed length came from.
Ease the pucker first. Pinch the fabric a couple of centimetres either side of the snag and stretch gently along the row, then across it. Half the slack usually walks back on its own.
Push what is left through to the inside. A snag repair needle, which has a roughened shaft that grips yarn, or a fine crochet hook, both do the job. Enter from the back, catch the loop, draw it through.
No hook to hand? Thread a sewing needle with a doubled length of thread so it forms a loop at the eye. Pass the needle from the inside out, right beside the snag. Slip the snagged loop through the thread loop, then pull the needle back through. The thread carries the loop to the inside.
Spread the slack. From the inside, tug the fabric gently in both directions across the three to six stitches next to the repair so the extra length redistributes instead of sitting in one lump.
Wash and dry it normally. Cotton relaxes in water, and most of the remaining pucker disappears on the first cycle. Our washing and care instructions cover the rest.

Leave the loop long on the inside. It does no harm there, it flattens under the next wash, and length is what stops it working back out to the front. If it genuinely catches on the inside, shorten it, but leave enough that the cut end cannot travel.

If the yarn has already broken

Two loose ends and a small opening is a different job. Working from the inside with matching thread, catch the whole loops on each side of the gap and draw them together without pulling tight, so the repair stretches with the fabric. Anything wider than a few stitches is worth taking to an alterations shop that handles knitwear. A pull that sits on or beside a seam is worth a closer look as well, since seam construction changes what happens next; that is covered in why hoodie seams split.

Snagging less in the first place

Do the zip up on anything worn over the top. An open runner swinging at chest height is the most reliable snag machine in the wardrobe.
Close velcro before the garment goes in the wash and before it goes anywhere near a pile of sweats.
Check the inside of the washer drum and the dryer for burrs and chipped enamel. Cotton Incorporated lists burrs on machinery as a cause of snagged fabric in mills, and a domestic drum is no different in kind.
Wash inside out, with the drum no more than about two thirds full, so hardware has less to grind against.
Keep sweats off nails, screws and wire hooks. Fold them, and if hanging matters to you, read hang or fold first.
Keep a snag repair needle with the spare buttons. Snags get worse the longer they are worn.

What the tests settle, and what they do not

Snag test methods measure how a fabric responds to one mechanical action for a fixed number of cycles. They rank fabrics against each other under a controlled beating. They do not predict what a given week will do to a garment, and the standards bodies say so themselves. The Woolmark Company makes the same admission about its surface tests in the Woolmark Specification SF-2: 2016, writing about pilling in wool apparel fabrics:

Due to the many factors affecting pilling there is no universally accepted test method that accurately predicts the likely propensity of a fabric to pill during use.

The same specification notes that the same fabric worn by different people in similar circumstances may behave quite differently. Snagging sits in that category too. It is a property of the fabric, the object that caught it and the person carrying both.

So treat a snag as maintenance rather than damage. The yarn is whole, the length is recoverable, and the only irreversible step is the one with scissors in it.

Sources

ASTM International, D3939/D3939M-13(2017) Standard Test Method for Snagging Resistance of Fabrics (Mace), 2017. store.astm.org/d3939_d3939m-13r17.html
ASTM International, D5362-13(2018) Standard Test Method for Snagging Resistance of Fabrics (Bean Bag), 2018. store.astm.org/d5362-13r18.html
Cotton Incorporated, Technical Bulletin TRI 3015: Guide to Evaluating and Reducing Holes in Knitted Fabrics, 2002. cottoninc.com
The Woolmark Company, Woolmark Specification SF-2: 2016, Flat Woven, Pile Woven and Pressed Felt Apparel Fabrics, 2016. woolmark.com