Techniques
Felting: shrinking wool on purpose.
The same thing that ruins a sweater in a hot wash makes felt. Wool fibers tangle and lock together for good, and once you know what drives that, you can control it to make fabric, shapes and objects.
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Why Wool Felts
Each wool fiber is covered in tiny overlapping scales, a bit like roof shingles. Fibers slide easily one way and catch the other way, so when they're pushed around they creep in one direction, tangle and can't back out. Crimp adds to the tangle.
| Factor | What it does |
|---|---|
| Moisture | Lets fibers swell, soften and move |
| Heat | Speeds things up; warm to hot water felts faster than cool |
| Soap | Helps fibers slide past each other so they tangle sooner |
| Agitation | The essential ingredient: rubbing, rolling, stabbing or tumbling |
| Sudden temperature change | Shocks the fibers and adds to shrinkage |
Remove agitation and wool barely felts at all, which is why careful hand washing is safe. See Wool Care & Lanolin.
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Three Ways to Felt
| Method | Starts with | How | Good for |
|---|---|---|---|
| Wet felting | Loose, unspun fiber | Layers of fiber wetted with warm soapy water, then rubbed and rolled until they mat into fabric | Flat felt, scarves, vessels, slippers |
| Needle felting | Loose fiber | Stabbing dry fiber with barbed needles that drag fibers into each other | 3D figures, fine detail, adding designs to felt or knits |
| Fulling (felting knits) | Knitted, crocheted or woven fabric | Washing hot with agitation until the stitches blur and the fabric shrinks and thickens | Bags, slippers, mittens, coats |
"Felting" and "fulling" are often used interchangeably. Strictly, felt is made from loose fiber with no yarn at all, while fulling finishes cloth or knitting that already exists. Mills full woven cloth on purpose: Woolen vs. Worsted covers how, and Boiled Wool is fulled knitting made industrially.
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Which Wool Felts Best
- Untreated animal fiber only: sheep's wool, alpaca, mohair and other animal fibers felt; cotton, linen, acrylic and nylon don't. Blends with a little synthetic felt more slowly and less firmly.
- No superwash: superwash wool is treated specifically so it won't felt. See Superwash Wool Explained.
- Watch out for bright whites: some heavily bleached white wools felt poorly. Swatch first.
- Fine wool for wearables: merino and other fine wools make soft, drapey wet felt for scarves and garments.
- Medium and coarse wool for sculpture: coarser, springy wools (often sold as core wool or batts) felt firmly and are the usual base for needle-felted figures, with finer wool on the surface.
- Breed matters: some breeds felt in minutes, others resist. Shetland and Icelandic felt readily.
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Wet Felting a Flat Piece
- 01Lay out thin wisps of fiber in one direction, then a second layer at right angles. Two to four even layers is typical. Keep the layer slightly larger than you want, because it will shrink.
- 02Wet it with warm water and a little soap (olive-oil soap or dish soap both work), pressing gently so the fiber is soaked through. A sheet of net or bubble wrap on top keeps fibers in place.
- 03Rub lightly at first, increasing pressure as the fibers start to hold together. This stage is called prefelt when it holds its shape but still pulls apart.
- 04Roll the piece in a mat or bubble wrap, turning it often so it shrinks evenly in both directions.
- 05Test with a pinch: when fibers no longer lift away from the surface, it's felted. Throwing or kneading the piece firms it further (full it).
- 06Rinse and shape: rinse out the soap, a splash of vinegar in the last rinse is a common habit, then shape and dry flat.
Expect wet felt to shrink noticeably, often by a quarter to a third or more of its laid-out size, depending on the wool and how far you take it.
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Needle Felting Basics
- How it works: notches (barbs) along the needle grab fibers on the way in and push them deeper, tangling them with no water at all.
- Gauge: higher numbers are finer. Around 36 is coarse for shaping, 38 is a common all-rounder, and 40–42 is for fine detail and smooth finishing.
- Shapes: triangle needles are standard; star needles have more edges and felt faster; twisted needles leave a smoother surface; reverse-barb needles pull fibers outward to make fuzz.
- Work on a pad of dense foam, a brush mat or a wool mat, and stab straight in and out. Needles snap if you bend them in the fiber.
- Safety: felting needles are very sharp and barbed. Watch your fingers, use finger guards or a multi-needle holder, and keep needles away from children.
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Felting a Knitted Piece
- Knit loosely: use needles two or more sizes larger than the yarn calls for, so fibers have room to move.
- Swatch and wash: shrinkage varies a lot by yarn and machine. Knitted pieces usually shrink more in length than in width.
- Hot wash with agitation: a top-loading machine or hand agitation is easiest to control; check every few minutes. Old jeans or tennis balls in the load add friction.
- Stop when stitches disappear, then shape the piece while damp and let it dry over a form.
- Accidentally felted a sweater? It can't be reversed, but mildly shrunk wool sometimes can be. See How to Unshrink Wool.