Turning raw cotton into yarn is a multi-step process of cleaning, aligning, and twisting loose fibers into a continuous, strong thread. Whether done by hand with a simple spindle or on industrial machinery, the core principle is the same: short, fluffy cotton fibers get drafted (pulled thin) and twisted together until they lock into a structure that holds. Here’s how it works at every scale.
Starting With the Right Cotton
Not all cotton spins the same way. The single biggest factor is staple length, the measurement of individual fibers. Short-staple cotton (roughly under an inch) is harder to spin and produces a fuzzier yarn. Long-staple varieties like Pima or Egyptian cotton, with fibers over 1.25 inches, draft more smoothly and produce stronger, silkier yarn. If you’re spinning by hand, look for long-staple cotton sold as prepared roving or sliver from a fiber supplier.
Fiber fineness also matters. Finer cotton fibers pack more individual strands into each cross-section of yarn, which adds strength to thin threads. That’s why fine cotton works well for lightweight yarns, while coarser, thicker fibers are better suited for heavy products like denim or batting. Cotton with very coarse fibers limits you to thicker yarn counts because too few fibers fit into the yarn’s cross-section to hold it together.
Cleaning and Opening the Fibers
Raw cotton straight from the bale contains leaves, dirt, seed coat fragments, and other plant debris. In a mill, bales are fed into a blowroom where opener and cleaner machines break apart compressed clumps and shake out trash. Multiple bales get blended at this stage because no two bales have identical fiber properties, and mixing them produces a more consistent yarn down the line.
If you’re working with raw cotton at home, this step means picking through the fiber by hand, pulling apart any compressed sections, and removing visible bits of plant matter. It’s tedious but essential. Skipping it means lumpy, weak yarn full of specks.
Carding: Untangling the Mass
Carding is the step that transforms a messy heap of cotton into something you can actually spin. The fibers pass between surfaces covered in fine wire teeth, which separate individual fibers, pull out short or broken ones, and spread everything into a thin, cohesive web. That web gets condensed into a rope-like strand called a sliver (rhymes with “diver”).
At home, you can card cotton with hand cards, which are flat paddles studded with fine wire teeth. You load a small amount of cotton onto one card, then brush the other card across it repeatedly until the fibers are separated and evenly distributed. The result is a small, fluffy batt called a rolag that you can draft directly from while spinning. Cotton fibers are short and slippery compared to wool, so you’ll want cards with finer, more closely spaced teeth.
Combing: An Optional Upgrade
Combing goes further than carding. Fibers pass through straight metal teeth that lay them perfectly parallel to one another while pulling out all the short fibers (called noils) and any remaining debris. The result is a “combed sliver,” which spins into a noticeably smoother, more lustrous yarn. Mills use combing for finer yarn counts, typically anything above a 50s count. For everyday yarn, carding alone is sufficient. If you’re spinning by hand and want the smoothest possible thread, you can comb cotton using fine-toothed mini-combs or even a pet comb, though it’s slow work and you’ll lose more fiber to waste.
Drawing and Roving: Getting Ready to Spin
In industrial production, the next step is drawing. Six to eight slivers are fed together through a drawing frame, which pulls and stretches them into a thinner, more uniform strand. This blending of multiple slivers evens out any thick or thin spots. Mills typically run cotton through two or three drawing passes for consistency.
After drawing comes roving, where the strand is drafted even thinner and given a very light twist, just one or two turns per inch. This slight twist gives the strand enough cohesion to travel to the spinning frame without falling apart, but not so much that it can’t be drafted further during spinning. The output is a roving bobbin: a soft, slightly twisted rope of cotton ready for its final transformation.
If you’re spinning by hand from commercially prepared cotton roving, you’re essentially starting at this stage. The supplier has already cleaned, carded, and drawn the fibers for you.
Spinning: Where Twist Creates Yarn
Spinning is the core act. You draft the roving (pull it thinner) while adding twist, and the twist locks the fibers together into a continuous yarn. More twist produces a stronger, firmer thread. Less twist gives you a softer yarn but one that’s weaker and more likely to pill.
Spinning by Hand
Cotton’s short, slippery fibers make it trickier to hand-spin than wool. A tahkli spindle is the traditional tool for the job. It’s a small, lightweight spindle with a sharp metal tip that sits in a small bowl or dish, allowing it to spin at very high speed. That speed is key, because short fibers need more twist per inch to hold together.
The basic technique: hold the cotton fiber in your left hand and the spindle in your right. Catch a few fibers on the hook at the top, pinch them against the hook, and draw a small amount of fiber out of the mass. Keep the spun yarn at a 45-degree angle so the twist travels up into the drafting zone. Pinch just below where the twist meets the undrafted fiber to control how far the twist goes, then gently pull back with your fiber hand to thin out any thick spots. Once you have about 16 inches of yarn, give the spindle a strong spin to tighten everything up. You can even lift the spindle off its support to let it dangle freely, using the yarn’s own tension to set the twist.
You can also spin cotton on a spinning wheel, though a wheel with a high ratio (meaning the flyer spins many times for each treadle) works best. Cotton needs significantly more twist than wool, and a low-ratio wheel will have you treadling furiously to keep up.
Industrial Spinning Methods
Mills use two main approaches. Ring spinning feeds roving through a set of drafting rollers and onto a rotating spindle, producing a smooth, strong yarn suited to fine fabrics. Rotor spinning (also called open-end spinning) skips the roving stage entirely, feeding carded sliver into a high-speed rotor that separates and re-twists fibers in one step. Rotor-spun yarn is about 19% weaker than ring-spun yarn of the same thickness, though it’s faster and cheaper to produce. Rotor yarn also has a slightly bulkier, fuzzier character that works well for casual fabrics, towels, and denim.
Plying: Balancing the Twist
A single strand of yarn (called a “singles”) tends to kink and twist back on itself because of the spinning twist stored in it. Plying solves this by twisting two or more singles together in the opposite direction. If you spun your singles with a Z-twist (clockwise), you ply them with an S-twist (counterclockwise). The opposing forces balance each other out, producing a yarn that hangs straight and behaves predictably in knitting or weaving.
Getting the direction right matters more than you might think. Yarn plied in the same direction as its singles twist will unravel during use. One hand-spinner testing this found that yarn spun with S-twist and plied with Z-twist held together perfectly during crocheting, while yarn twisted and plied the same way immediately started losing its ply. The convention for most right-handed spinners is Z-twist singles, S-twist plying.
Scouring: Washing the Natural Waxes Out
Raw cotton fibers are coated in natural pectins and waxes that repel water and resist dye. Scouring removes these coatings so the finished yarn absorbs moisture and takes color evenly. The traditional method uses an alkaline solution (sodium hydroxide) heated to boiling for about 45 minutes. Newer enzyme-based methods work at lower temperatures, around 130°F (55°C), and a mildly acidic pH, which is gentler on the fiber and more environmentally friendly.
If you’ve spun cotton yarn at home, a simpler approach works: simmer the skeined yarn in water with a small amount of washing soda for an hour, then rinse thoroughly. This removes enough wax to let the yarn accept dye and feel softer against the skin.
Finishing Touches
Industrial yarn goes through a winding step where it’s transferred to cones at high speed, passing through sensors that detect and remove slubs (thick lumps) and thin spots. Some cotton yarn is also mercerized, a process that briefly exposes it to a strong alkali solution under tension. This swells the fibers permanently, giving the yarn a silky luster and improving dye uptake by about 20%.
For hand-spun yarn, finishing is simpler. After scouring, you hang the skein with a light weight attached to the bottom and let it dry under tension. This sets the twist and gives you a yarn that won’t kink when you try to knit or weave with it. Some hand-spinners snap the wet skein a few times against a table or countertop to bloom the fibers slightly before hanging it to dry.