What are felting and fulling, and how do they compare?
Felting: As Bette Hochberg explains in Fibre Facts, felting “is the traditional method of making non-woven fabric” using unspun sheep wool (e.g., from batts or rovings). Other protein fibers can also be felted, though their felting ability varies. (Angora, for instance, felts much more quickly and easily than wool.) There is more than one method of felting.
Here are some videos demonstrating various types of felting: Beginning Felting from Outback Fibers; Nuno felting by Gika Rector (I’m envisioning a colorful dinner jacket); Needle Felting 101 by Ricë (“rhymes with Lisa”); and Making a Felt Sheep by Kim Chatel. Check out Sheep Hollow Farm Life blog for some fun and easy beginning hand (wet) felting projects. If you want something a little more challenging, watch Jasmine Zorlu use wool felt to demonstrate freeform hat blocking (I love hats).
For felting instructions in pdf format (also the source of the pic above, visit Lori Flood Felted Fibers.
Fulling: After woven or knitted, the resultant cloth can be fulled. Ms. Hochberg explains: “When felting is used to a limited degree on woven cloth, it is called fulling” (p. 23). (Think of the Austrian boiled wool jackets.) However, after spinning, yarn also can be fulled. (See Musings and Instructions from a Long-Time Knitter Who Spins.)
The photograph of the 18th century engraving shows Scotswomen “waulking” (aka fulling) wool cloth. (Source)
How does felting or fulling happen? Each wool fiber has scales on its surface; if you look at a wool fiber through a microscope, it rather resembles fish scales. Whether by hand or machine, when hot water, agitation and soap “are applied, the fibre can relax or migrate only in the direction of its root end. … The serrated scales acts like a rachet, and hold the fibre interlocked with its neighboring fibres. When the fibres are locked into place, they form a cohesive piece of felt” (Hochberg, p. 23).
Where Did Felting Come From? Many historians think the Mongols pioneered felting. Curiously, while the Mongols spun their thread, the cloth they used was generally felted, not woven or fulled. In fact, their yurts were felted. (See and Ulaantaij and YurtInfo for great pictures and history.) If you think about it, that the Mongols made felted yurts was sensible: Felted wool is highly wind resistant.
So weave wool into material and sew a jacket or knit wool yarn into a sweater, THEN full them. Result? A very warm garment with increased wind resistance. Remember, however, if you full a sweater or a jacket, it SHRINKS in size. How much shrinkage depends on many factors, including the actual fiber used (e.g., the hair of what animal, fiber crimp, etc.), the temperature of the water, the length of agitation, at what sett you wove the fabric, and your knit or crocheted stitch gauge.
Felting can be fun projects to do with children. When doing wet felting, I have always felted outside on long tables. Felting with children seems to be like washing cars with them: everyone gets soaked and has a great time!