Part 1: What is Carding?

We’re putting together this series of articles going into some depth about the process of making yarn, its intricacies and challenges, and all the differences throughout the journey. We’ll also be introducing you to our machines in the mill and telling their stories as well. In this first instalment, we’re delving in to the world of carding. It isn’t the very first step in our process, but it’s the first mechanical one that happens under this roof, so that’s our starting point.

Read part two here.

Since I first read that the phrase “On The Cards” may have originated in spinning mills to reference what the fibre/order of the day was to hold, as literally meaning “what sort of wool is on the carder today?” I’ve been fascinated by the importance of the carder in any spinning operation. I’ve since found out there’s a much higher chance the saying comes from tarot cards, where ones fortune could be discovered by finding out what’s on the cards, but my love of the carder hasn’t abated one bit.

There’s a reason that the carder is often called the heart of the mill. Whether woollen, worsted or semi worsted spinning, it forms an utterly vital, albeit slightly varied, role within making yarn. It’s usually one of the biggest, heaviest machines in a mill, and quite often the one deemed to be more of an art than a science. Which as you can imagine, makes learning to card just a little bit tricky.

But I’m getting ahead of myself. Let’s go right back to the beginning: what is carding? The shortest possible description would be that carding takes a tangled mass of fibre and through a pulling action presents it in a new form ready for onward processing. In a bit more depth, there are four objectives:

1. To separate fibre that’s in tufts by pulling neighbouring fibres apart without breaking.
2. To remove some impurities (such as dust and vegetable matter like grass, hay and straw).
3. To mix and blend fibre together.
4. To form a sliver of overlapping and partially aligned fibres ready for onward processing.

For hand spinners¹, this involves either hand carders (a pair wooden paddles, usually about 15cm x 20cm / 6” x 8”, with faces covered in bristles) or a small drum carder (just like hand carders, but rather than the bristles being mounted on paddles, they’re on a pair of drums that rotate, either hand cranked or powered by a small motor). The purpose of these hand carders is usually to make a batt of fibre, a roughly aligned pad, almost like extremely loose felt, often around 2-5cm /1-2” thick and anywhere from 15cm x 30cm to 30cm x 75cm / 6” x 12” to 12” x 26” when laid flat.

In a mill however, batts of fibre aren’t so much use. For a start, to empty, or doff the fibre from a hand or drum carder, you need to stop the carding process, peel off the fibre and restart. This wouldn’t be ideal in a commercial set up - machines on stop are the enemy of efficiency. Secondly, there’s not much that can be done with a batt in a mill environment. They’re relatively small, and once again, not continuous.

In a commercial mill, carders will have the ability to doff (be emptied of fibre) whilst still running. Depending on the type of carder, the doffing method varies a little. So what are the types of carder²? There are three primary methods of spinning wool, as mentioned above: woollen, worsted and semi worsted. For the purposes of this post, I’ll be putting worsted and semi worsted together - the differences in carding are very slight, and mostly come down to gear ratios, speeds and sizes - the principles are identical.

Worsted Carder

A worsted carder is the smaller of the two types, as it has far less to do. A hopper will feed the rollers, a mechanism of drums that pull the wool in at a pre-determined rate and then through a series of workers and strippers the fibre is teased open and roughly aligned. At the outfeed end of the carder, the doffer peels away a fine web of fibre, scoops it together into a delightfully satisfying sliver³ and coils it into a can. Big, modern carders have a truly overwhelming capacity, with all the bells, whistles, sensors and gizmos you could possibly imagine, processing utterly vast amounts of wool.

Workers and strippers are two of the types of drums you'll find on a commercial carder. They work in pairs, and surround the largest drum in a section, known as the swift. The worker, which is rotating more slowly than the swift, grabs a small amount of fibre with each tooth point, gently pulling that particular tuft open. Its corresponding stripper removes the fibre from the worker, and deposits it back on the swift. Through a number of actions passing from swift to worker to stripper and back to worker, the fibre is gradually opened and aligned as it works its way through the carder.

Woollen Carder

A woollen carder is usually comprised of two or three sections. It’s much, much bigger than a worsted carder, because it has to work an awful lot harder. The first section, known as the scribbler, is very similar to an entire worsted carder. It’s primary function is to start the carding process, teasing open the locks and lumps of fibre. It also produces a web of fibre, peeled from the final drum and scoops it together into a sliver, but rather than coiling this into a can for further processing, the fibre is laid at 90° across the infeed of the second section.

The purpose of this action is to ensure the blend across the full width of the carder is as even as possible. Any inconsistencies in the wool that was fed from the hopper are all but eliminated by rotating the fibre through 90°. In the second section, the teeth on the drums of the carder are much finer, and rather than big, heavy actions to start opening the fibre, they are working to perfect the web of wool fibres on the drums, continuously blending, refining and aligning. Some woollen carders have a third section after this, which is similar to the second, but works to further refine and blend the fibres. This is particularly common in mills processing fine and superfine wools - think Merino lambswool and cashmere.

After the final section, the fibre is once again presented in a thin, even web. By this point, the web is much finer, and much more evenly blended than after the first sections of the carder (or indeed, a worsted carder). It should be free of lumps (slubs), neps (small, dense balls of short and fine fibres) and weight variations (thick and thin spots). The web is now ready to be divided into a number of narrow rovings that are wound on to a bobbin ready for spinning. The number of rovings produced varies significantly by the size of the carder and the fineness of the roving. Typically, the carder produces anywhere from 70 to 220 ends (rovings).

¹ I must confess to not being much of a hand spinner, so whilst I do understand the principles, there are a plethora of far more useful resources going into depth on hand carding than I possibly could.

² Like everything to do with yarn production, there are endless variations on types of carder. Cotton and Flax/Linen production use very different machinery, so this post very much only focuses on wool spinning.

³ Some people would call this a carded roving, others a sliver (either pronounced sli-ver or sly-ver), but for simplicity I’m going to stick with what we use: sliver (and we pronounce it sli-ver, like river)