The Perfect Knit Sweater: How to Spot One, Keep It Forever, and Wear It the French Way

Eugénie Trochu is a Who What Wear editor in residence known for her transformative work at Vogue France and her Substack newsletter, where she documents and shares new trends, her no-nonsense approach to fashion and style, plus other musings. She's also working on her upcoming first book that explores fashion as a space of memory, projection, and reinvention.

Not the sweater you regret in March, not the one that pills after two days, not the cardigan that collapses like an old sock. The real one. The one that ages well, develops a patina, and eventually becomes an extension of you. The truth is, most sweaters look good… until the first friction from a bag or a coat. The good one passes that test - and a few others.

1. How to Recognize a Truly Good Sweater

The material tells you before the label does. If you touch it and you think, “yes, this one, I want to keep it for a long time,” that’s a good sign. The best candidates:

• 100% merino wool (flexible, warm, no reason to pill)
• Dense cashmere (not thin like a tissue)
• Alpaca blends (durable if the knit is tight)
• Combed virgin wool (the structure doesn’t collapse)

Avoid mixes like acrylic and a hint of dream: they pill before you’ve even reached the register. The knit must be tight. Pull it slightly: if you can see your finger through it, forget it.

A good sweater is a small piece of architecture. Not a cloud. Weight matters. It’s not a weightlifting contest, but a sweater that’s too light won’t survive a French winter. It needs some body. Not limp. Not sad.

The shoulder test. The seam should fall right there, not lower. A good shoulder structures everything - even a badly chosen pair of jeans.

2. How to Avoid Pilling (and Save Your Dignity)

The sweater needs rest. Never wear the same one two days in a row. Like a good wine, it needs time to recover from the effort. Sweater lingerie: