According to my copy of “The American Heritage Dictionary Of The English Language”, the word “boucle” means: “A type of yarn, usually three-ply and having one thread looser than the others, which produces a rough texture cloth.” The Dictionary goes on to add that the word comes from the Old French “boucle” which means to curl or to buckle. Quite a fitting word to use for this type of novelty yarn since the looser ply appears to have bucked, causing the yarn to have a curly appearance, it takes a minimum of three plies to spin a viable boucle yarn, and cloth made from this type of yarn will have a rough appearing texture.

While this description tells us that the basic structure of the yarn is a three-ply with one ply being looser than the other two plies, it does not tell us how to spin so that one ply will be looser than the others - so loose that it will buckle and curl and produce the texture we want. The trick to doing this lies in the twist direction and grist of the plies.

A traditional boucle yarn consists of three parts:
1. A thin ply
2. A thick ply
3. A binder

Each of these parts plays an important role in creating the final yarn.

The thin yarn is usually the ply that is spun with Z (right, clockwise) twist and which has a high degree of twist. This is the ply that serves as the base yarn or the core yarn for creating the boucle.

The thick yarn is usually the ply that is spun with S (left, counterclockwise) twist and which has a low degree of twist. This is the ply that will curl and buckle and give texture to the yarn.

The binder is the ply that holds the thick and thin plies together to make a viable yarn.

To combine the three parts to create a boucle yarn:

1. Spin a bobbin of thin Z twist singles with a high degree of twist.

2. Spin a bobbin of thick S twist singles with a low degree of twist.

3. Ply the two yarns together, plying in the same direction as the direction of twist in the thin yarn. Example: The thin yarn is spun Z - therefore the direction to spin for plying is also Z. When plying, the two yarns must be held at differing tensions: The thin yarn is held under tighter tension while the thick yarn is held under looser tension. The idea is to wrap the thicker yarn around the thinner yarn. It is the wrapping of the thicker yarn around the thinner core that creates the boucle texture. Note that when the yarns are being plied, more Z twist is being added to the thinner yarn while twist is being removed from the thicker yarn.

4. Add the binder ply. Since the last spinning direction (plying the thin & thick yarns together) was done Z, the binder ply will be added by spinning S. At this point, we’re actually spinning a cabled yarn.

Binder plies:
Binder plies actually cable the yarn. And we have several options
First, we can simply ply the yarn back on itself, plying with S twist.
Second, we could spin our own Z twist binder yarn and use that for plying S.
Third, We can use a commercially spun binding yarn such as sewing thread. Since we are going to be spinning S when we add the binder thread, check the twist direction of the thread or yarn you plan to use for the binder to see if it will unspin when it’s used for plying S. If it will unspin, then more twist will need to be added to compensate before it can be used as a binding thread.