Roving is a form of fiber for spinning into yarn or thread. Normally, a strip of roving will be continuous, about 1-2 inches (2-5 cm) in diameter with a roundish cross section. While there are many different fiber preparations available to the handspinner, roving refers to fiber that has been carded and drawn out into a long strip. The term is generally reserved for animal fibers commonly including sheep's wool, alpaca or llama fleece, because these animals produce a quality of fiber that works well for carding, with a fairly consistent staple length. Roving can also be used for needle felting, wet felting, thrumming, weaving, and normal knitting. I have not attempted to crochet with roving, but I do not suspect that it would stand up to the stress very well.
Because roving is carded, individual fibers are not necessarily all oriented in the same direction, as you would expect from a combed preparation. Combing removes the short, curly or scruffy fibers from the longer smoother fibers, where carding leaves them incorporated with the fiber. Because of this inconsistency, roving is springier and will produce a more lofty, bouncy yarn when spun. In my spinning, I find that roving requires more pre-drafting before spinning, and that it will kink up with less agitation, and need re-pre-drafting. Incidently, sliver (pronounced sly-ver) is a fiber preparation which is normally carded, then passed through a diz to achieve uniform thickness and condense the roving.
Commercial roving is prepared on carding machines which employ a series of cylindrical drums covered with spiky fabric to catch the fibers and open them. The manner in which the fiber is removed from a commercial or small scale drum carder will determine whether it becomes a roving or a batt. A strip of batting is significantly wider and flatter when laid out from the roll (think of polyester or flannel quilt batting), and needs to be divided into thinner strips before it can be stretched and drafted for spinning. A large roll of roving is called a bump. Theoretically hand cards, essentially paddles with spiky fabric, can be used, but normally they are too small to make an effective roving, and the resulting small product is called a rolag. Rolags behave much like roving, but you need a large number of them to spin a substantial length of yarn.
Spinning with roving is perhaps the most straightforward handspinning operation available. I spin on a drop spindle, but these directions can be directly adapted for a spinning wheel, just without the - pinch, grab, spin, drop the spindle, curse!, try again - bit. Because what you do before you spin is so important to your finished yarn, I'm including my advice on the subject.
- It's helpful to wash and dry your hands and apply your favorite moisturizer first, to prevent snagging fibers on rough skin or nails. Where I live, in New England, it gets very cold and dry during winter, so this step is essential. Get comfortable. Have some tea. Prepare to indulge in tactile pleasure.
- To get a length of roving to work with, take your bump, unwind the fiber to about the length of your arm and hold it near the bump with your hands about six inches away from each other. You may need to adjust this distance, it will rely on the staple length of your fiber. Gently tug your hands away from one another. The roving should start to thin out in the middle and finally separate completely. Never, under any circumstances, cut the fiber with a pair of scissors. Don't do it!
- This really is the most important part of the spinning process. Even though you've presumably just paid someone to open up the fiber for you, you need to do it again. To pre-draft your little hank of fiber, start at one end, hold it in both hands, at about the same distance or just slightly closer together than before and start pulling the fiber very gently. This time, you don't want to separate it completely, just get the fibers to slide against each other freely. It's a matter of personal preference how thinly you draw the fiber, but keep in mind that your finished yarn will be less than a quarter of the thickness of this puffy loose fiber when it is twisted on itself.
- Roving can be spun worsted, from the fold or in just about any other manner desired, but this is a bigger topic, that deserves its own node.
http://www.llamapaedia.com/wool/glossary.html -=- an excellent spinning glossary
http://www.bellaonline.com/site/spinning -=- Bella Online, a women's newletter has some spinning and fiber-art information
http://www.joyofhandspinning.com/ -=- the definitive online handspinner's manual