Mistake or Miracle? How to Felt

feltRemember when your favorite sweater got lost in a load of laundry, and the next time you saw it, it had shrunk into a miniature, blanket-textured doggy sweater? There’s a name for this phenomenon: felting. And if you plan ahead, you can use the very same disastrous process as a design tool to create extraordinary results.

The process of felting raw fibers has been used for centuries. But felting knitwear (which is called “fulling”) didn’t hit the mainstream Western knitting community until the mid 1980s.

Felting expands and tightens fiber at the same time, essentially transforming the look and feel of most knitted garments. Today, several talented designers — especially Nancy Lindberg and Suzanne Pufpaff — specialize in creating patterns for this medium.

If you don’t believe it’s possible to turn a huge, floppy, washcloth-like knitted item into a strong, structured hat or pair of weather-resistant mittens, you must try felting.

Successful felting depends on three conditions: moisture, heat, and movement.


When wool fibers get moist, their core begins to swell. This causes the fine layer of scales along the fiber surface to open.


The scales open more fully at a higher temperature.


As with a pile of coat hangers, these open scales readily catch onto one another. The more you agitate the materials, the more enmeshed the scales become. The fiber becomes matted and dense, reducing the overall size of the fabric being washed.

Additional Factors

Studies have proven that the felting process occurs more readily when the pH level of the water is higher. Adding a small amount of soap to your felting water will help, because it naturally raises the pH level.

Likewise, you can stop the felting process and close the fiber scales by adding a moderate amount of vinegar to your cold-water rinse. This lowers the pH level.

Let’s Do It!

Step 1: Knit your garment. If this is your first felting project, stick to a pattern written specifically for a felted garment. This will eliminate the need to recalculate the pattern gauge to accommodate shrinkage.

Step 2: Place the garment in a washing machine with the hottest water your machine will allow. Set the water level on low. Add anywhere from 1/2 to 1 cup of detergent to the water, and set the machine on agitate for at least 15 minutes. (For more help on choosing a detergent, click here.)

Step 3: Check the garment frequently until it has felted to the desired size and thickness.

Step 4: Remove the garment from the washing machine and rinse in cold water.

Step 5: Block the item into the desired shape. If it is a hat, find a mixing bowl of a similar shape to use as a mould.

Step 6: Let dry in a cool, dark place away from strong sunlight. It may take a day or two to dry completely.

If after a few days you realize the garment hasn’t felted enough, you can begin again at step 2 and repeat the process.

Tip 1: Not All Wools will Felt

The best wools for felting are Merino and Debouillet, followed closely by Comeback, Cormo, and Rambouillet. Longwools do not felt nearly as well.

If you are restricted to commercial yarns that don’t specify the exact breed, don’t fret. There are many excellent commercial yarns for felting, which we’ll examine in detail next week.

“Superwash” or any other machine-washable wools have been specially treated so they won’t felt when placed in the washing machine. This is good news for your sweaters and socks, but bad news for felting. Likewise, the presence of any synthetics in the yarn impedes the felting process. However, other natural fibers such as mohair and alpaca will felt beautifully.

Tip 2: Take Care in Planning Gauge and Size

Fibers need ample room to work themselves together, so you’ll need to knit at a significantly looser gauge than you normally would. This means using larger needles and knitting a garment that’s often nearly twice the size of the intended, felted result.

If you knit too tightly, the fabric will only felt a limited degree. You may be stuck with a garment that’s still too big and appears only half-felted, with visible lumps and stitches instead of a cohesive, smooth material.

Tip 3: Don’t Underestimate the Power of Friction

You can significantly speed up the felting process by adding an old pair of jeans to the washing machine. This gives extra friction to the felting process.

Felting produces a lot of loose lint, so you may want to put your items in a zip-up pillowcase to keep your washing machine clean.

Tip 4: Timing is Key

The felting process can take several minutes to get started. No matter how tempted you may be to run upstairs and get a cup of tea, don’t!

Once the felting truly begins, you’ll want to check your progress frequently — even every 45 seconds or so. Timing is critical and felting irreversible. Even a minute too many can mean the difference between booties for you and booties for a 10-year-old child.

Tip 5: Know When to Stop

If moisture, heat, and movement cause felting, these same factors also work to stop it. To stop the felting process, submerge the garment in very cold water.

You can continue felting at any time, so don’t be afraid to do this as often as you need while checking the size.

Once you’re sure of the size, add a dash of white vinegar to the rinse water. This helps close up the fiber scales and stop the felting process.

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  • I believe Icelandic wool is a “superb felter”, as you said in a review.

  • Perhaps you might consider adding some notes on hand felting? Some of us don’t have (or have access to) top-loading washing machines where the progress can be stopped and checked frequently (I have a front-loader and I cannot check because the “tub” of water is sideways and would all spill out!). Thanks for a wonderful post.


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