Vintage sweaters are one of the best reasons to shop secondhand. The wool is often denser, the colors are bolder, and a well-made one costs less than a new acrylic blend that will pill by February. But thrift racks are also crowded with knits that look fine on the hanger and fall apart after a single wash. The difference between a find and a mistake usually comes down to five minutes of careful inspection.

Work through these checks in order. The first two will eliminate most problem pieces before you get attached.

Start With the Fiber Label, Then Trust Your Hands

The label is usually sewn into a side seam or the back of the neck, and on older pieces it may be faded enough that you have to angle it toward a window. Read it anyway. A few terms are worth knowing:

• Virgin wool, lambswool, Shetland, merino: all wool, with different softness and density. Virgin wool simply means it hasn't been recycled from scraps.
• Mohair and angora: fluffy, lofty, and prone to shedding. Expect a halo of loose fibers, especially on dark coats and car seats.
• Cashmere: light, warm, and quick to pill anywhere it rubs. Pills are normal; thinning is not.
• Orlon, Dacron, Ban-Lon: mid-century trade names for acrylic, polyester, and textured nylon. Not inherently bad, but they hold static, resist dye differently, and pill in their own way. They also won't feed moths.
• "Wool blend" with no percentages: a gamble. It could be 80 percent wool or 20 percent.

If the label has been cut out, your fingers have to do the work. Wool feels dry and slightly grippy, and springs back when you crush it. Acrylic feels slick and a little squeaky. Cotton feels cool and has almost no stretch. Cashmere feels almost weightless for its warmth.

Moth Holes Hide Where the Light Doesn't Reach

Hold the sweater up to a window or under a bright overhead light. Moth larvae feed in dark, undisturbed folds, so the damage clusters in predictable places: armpits, the inside of the neckline, the underside of folded cuffs, and along the hem where the fabric doubles over. Look for small clean holes a few millimeters across, threadbare patches that look almost translucent, and tiny grainy specks or fine webbing left behind by larvae.

Then test with your hands. Pinch the fabric between your fingers and pull gently in two directions. Sound knitting stretches and returns; weakened knitting opens into a visible gap. Run the same test along the shoulder seams and under the arms, where stress and sweat do their own damage.

One isolated hole near a seam is often just wear, and a good mender can fix it. A scattered constellation of holes across the front, or thinning you can see through, is a different story — that sweater will keep unraveling no matter how carefully you wash it.

Pilling and Fuzzing: Read the Surface Honestly

Pilling doesn't automatically mean poor quality. Short fibers work loose with friction, and even expensive cashmere pills under a bag strap. What matters is the state of the surface right now. Look under the arms, along the sides, at the cuffs, and wherever the sweater rubbed against a coat. If pills have already been shaved or picked off, you'll often see a thin, slightly matte patch underneath.

Watch for felting too: stiff, matted areas where heat and moisture have fused the fibers permanently. A soft halo is fine. A crusty, compressed patch on the front of a cardigan will never come back.

Cuffs, Collars, and Hems: The Snap-Back Test

Ribbing is the part of a sweater that gives up first, usually because the sweater was pulled on by the cuffs or hung on a hanger for years. Stretch the cuff sideways and lengthwise, then let go. It should snap back to roughly its original size within a second or two. If it stays loose and floppy, the elastic memory of the ribbing is gone.

Compare each cuff to the sleeve above it. A cuff stretched to nearly twice the width of the sleeve will dangle and look tired no matter what you do. Check the neckline the same way — a crew neck that has been stretched over hangers will sit awkwardly and gap at the collarbone. Also lay the sweater flat and look at the elbows: bagged, bulging elbows on a heavy wool knit are difficult to reverse.

Replacing cuffs is possible, but it's real knitwear repair, not a quick fix. Factor that into whether the price still feels worth it.

Smell the Armpits and the Neckline

Bring the underarm area and the inside of the collar close to your face and breathe warm air onto the fabric to loosen any oils, then smell. Different odors mean different problems:

• Smoke can often be reduced with airing and several gentle washes, but it may never fully leave a dense wool knit.
• Perfume and musk are stubborn and personal. If you like it, fine. If you don't, it will sit next to your skin all day.
• Mildew or damp basement is the one to walk away from. The smell usually comes from prolonged moisture, and washing rarely removes it completely. If you're sensitive to mold or have a respiratory condition, don't bring it home.

The Two-Minute Check Before You Pay

1. Read and photograph the fiber label.
2. Hold the sweater to the light and inspect armpits, collar, cuffs, and hem.
3. Stretch the ribbing and watch for the snap-back.
4. Pinch and pull gently at any thin spot.
5. Turn it inside out. Look for loose ends, uneven repairs in mismatched yarn, and faded patches.
6. Check shoulder seams and underarm seams for strain or splitting.
7. Work the buttons or zipper on a cardigan all the way through.
8. Measure it flat — pit to pit, shoulder to shoulder, sleeve length — and compare with a sweater you already own. Bring a tape measure.
9. Step into daylight to check the color, since store lighting flatters everything.
10. Ask about returns before you commit.

Getting It Home and Keeping It Well

Once a sweater passes, treat it gently. Wash wool and cashmere in cool water with a detergent made for protein fibers, by hand or on a wool cycle, then press the water out against the side of the basin instead of wringing. Lay it flat on a towel to dry, reshaping it as it dries. Skip the hanger, which stretches shoulders and cuffs, and store knits folded.

If you're worried about moths, keep the new arrival sealed in a bag away from your other woolens for a couple of weeks, and keep your closet clean and aired. Cedar and lavender smell pleasant but won't kill larvae on their own. If you have had an infestation, professional cleaning is the safer route.

A small hole can be darned, and a slightly loose cuff can be tightened by a knitter, but nothing rescues a sweater that smells musty or sheds fibers every time you move. Buy the one that fits, smells clean, and feels good against your wrist. That sweater will outlast half the new ones in your drawer.

Photo: Taras Chuiko / Pexels