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Cotton vs. Polyester Thread

Is cotton thread a thing of the past? Cotton is a wonderful, natural fiber that has been woven into clothing for over 5,000 years. But as the times and technology change, even so, does sewing thread.

There are four main thread characteristics to take into account when sewing:

  • Color: Pigment
  • Weight: Thread weights are ranked by a number system where higher numbers indicate a finer thread.
  • Fiber: Fibers can either be natural or synthetic.
  • Twist: The twist is the amount of spin of the thread fibers. A thread with a high amount of twist will be smoother and tougher.

Threads are either made of natural fibers, like cotton, wool, silk and linen, or they are made of synthetic fibers, like rayon, polyester and nylon.  We are going to discuss the two most common types of thread, polyester and cotton.

Polyester thread is a synthetic all-purpose thread. It is a good choice for most machine and hand sewing projects. Polyester thread works well with stretchy fabrics as it has much give to it. Because of the wax or silicone finish that often covers this thread, it slips through the fabric easily. Invisible polyester thread is also available and is an ideal choice for some projects.

Polyester is made to be stronger than most natural threads. It is important to avoid using polyester thread with natural fabric. Over time, the stronger polyester thread can break down the weaker cotton fiber of the fabric.

There are a number of other advantages to polyester thread:

  • Durable: Designed for heavy duty use
  • Strong: More tensile strength than rayon or cotton
  • Colorfast: Polyester fibers hold color pigment longer and through more washes
  • Retains shape: It has much give to it while still retaining its original shape
  • Variety of finishes: Matte finish, or medium to high-sheen finishes
  • Longer lasting: Not significantly affected by moisture, rot, mildew or most insects

As stated earlier, cotton thread has been used since the dawn of human existence. Even though it has been around a while, it does have its drawbacks. Cotton thread has low stretch and tends to break easily. However, it’s a good choice when sewing delicate fabrics and garments like lingerie.

Cotton has various finishes, each providing specific results:

  • Mercerized: This is a treatment that allows for better penetration of color into the thread which increases strength and gives a lustrous appearance.
  • Gassed: This is a technique where the thread is passed through an open flame, incinerating any stray fibers. The final result is a polished, silky finish.
  • Glazed: Glazed thread is treated with a wax coating that protects the thread and gives it a glossy coating. A downside is that the glaze does rub off so it is not recommended for machine use.
  • Cotton-wrapped poly: Most cotton-wrapped poly threads are party cotton and part polyester. It tends to resemble the characteristics of poly more than cotton.

Whether you choose cotton or polyester thread, it is important to keep in mind the basic thread characteristics so you can be sure your finished product looks great and will last.