Plying

Key takeaways

Plying belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Plying to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Plying from memory before moving on to harder problems.

Reference excerpt

In the textile arts, plying (from the French verb plier, "to fold", from the Latin verb plico, from the ancient Greek verb πλέκω.) is a process of twisting one or more strings (called strands or plies) of yarn together to create a stronger yarn. Strands are twisted together in the direction opposite that in which they were spun. Plied yarns will not unravel, break, or degrade as easily as unplied yarns. When enough twist is added to the plies to counter the initial twist of each strand, the resulting yarn is "balanced", having no tendency to twist upon itself. The number of strands used to make the yarn is usually the same as the number of plies it has. Two-ply yarn means two strands were used, three-ply yarn means three strands were used, etc. Embroidery floss is generally a six-ply yarn, for example. There are some exceptions to this, most notably in chain plying.

Plying handspun yarns

There are two common ways to ply a balanced yarn: regular and chain plying. Both methods involve the manipulation of "singles"—unplied strands on their own—into multiple-ply yarns by applying twist in the opposite direction than how the single was spun. For example, if in spinning the single the wheel was spinning clockwise (called a "Z" twist, as on any given side the fibres appear to cross each other like the line in the middle of the letter "Z"), the wheel must spin counter-clockwise (an "S" twist) in order to ply it.

Regular plying

Regular plying consists of taking 2 or more singles and twisting them together. This can be done on either a spinning wheel or a spindle.

When plying, the singles are kept separate, either with the fingers or with a tool. This tool can be anything from the top of a salt dispenser, and the singles threaded through the holes, or a specially carved piece of wood with holes in it. The singles are kept separate to ensure that they do not get tangled and so the tension can be controlled. Most spinners who use spinning wheels ply from bobbins or spools. This is easier than plying from balls because there is less chance for the yarn to become tangled and knotted. So that the bobbins can unwind freely, they are put in a device called a Lazy Kate, or sometimes simply kate. The simplest lazy kate consists of wooden bars with a metal rod running between them. Most hold three or four bobbins. The bobbin sits on the metal rod. Other lazy kates are built with devices that create an adjustable amount of tension, which adds control to how much string is unwound using a given amount of force. Some spinning wheels come with a built-in lazy kate. On a drop spindle, two-ply is created by placing the spools on a lazy kate, tying the ends together onto the drop spindle, holding equal lengths of singles together and dropping the spindle. The weight of the drop spindle, combined with the twist in the singles, causes the drop spindle to turn in the opposite direction that the singles were twisted in until the two singles are plied together.

Chain plying Chain plying (also known as Navajo plying) consists of making large loops, similar to crocheting. Only one single is necessary, and if the single is already dyed, this technique allows it to be plied without changing the color scheme. The spinner first makes a loop on the end of the leader—the string left on the bobbin, which the new yarn is spun from—that is large enough to slip their hand through. They pull some of the working yarn through the loop. Then the spinner starts applying twist to the three plies, consisting of the two sides of the loop together with the yarn pulled through it. When the loop and the yarn are nearly fully plied together, a new loop of yarn is pulled through the initial loop, and spinning continues. This process is repeated until the yarn is all plied. This technique allows the spinner to try to match up thick and thin spots in the yarn, thus making for a smoother end product.

Center-pull ball plying Center-pull ball plying results in yarn similar in appearance to regular plying. However, it doesn’t require a lazy kate or multiple bobbins. It requires a single bobbin and a center-pull ball winder or a nostepinne to create the center-pull ball that is plied with. Once the ball is wound, the single from both the center and outside are held together, in a similar manner to the regular plying method, then twisted together. This results in a two-ply yarn. Center-pull ball plying results in one single being more tightly wound than the other, causing a fluffier and looser texture when knit, compared to the regular plying method.

Machined yarns Machines that ply yarn use the 'regular' method mentioned above. The main difference is that gears control the intake, making sure that the strands all have the same tension and the same length. Other than that, the process for plying is exactly the same as when hand done.

Novelty yarns Many novelty yarns make use of special plying techniques to gain their special effects. By varying the tension in the strands, or the relative sizes of the strands, or many other factors different effects can be achieved. For example, when a soft, thick strand is plied against a tightly twisted thin strand, the resulting yarn spirals. Another example is bouclé, which is a yarn where one strand is held loosely and allowed to make loops on the other yarn while plying.

Illustrations

Worked examples

Example 1 — a first encounter with Plying

Start with the simplest possible case. Write down what Plying claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Plying before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Plying ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Plying

In research: Plying appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Plying in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Plying is common in secondary-school and first-year university syllabi. It links to neighbouring topics Spinning, Yarn, so understanding it makes those chapters shorter.
In everyday life: Look for Plying outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Plying in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Plying means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Plying out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Plying in simple terms?

In the textile arts, plying (from the French verb plier, "to fold", from the Latin verb plico, from the ancient Greek verb πλέκω.) is a process of twisting one or more strings (called strands or plies) of yarn together to create a stronger yarn. Strands are twisted together in the direction opposit…

Why does Plying matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Plying?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Plying.