40 Weight Thread: The Embroidery Mystery Unraveled!

The world of embroidery threads can be very confusing. So many elements to consider—weights, fibers, uses—where do you begin? One very common question: What’s the deal with 40 weight thread?

Let’s examine some of the uses of 40 weight thread!

Machine embroidery threads in brown, red and purplePhotos via Leighlalovesyou

What is the difference in thread weight?

Thread weight is the thickness of the embroidery thread and works on a scale, typically between 30-120. The higher the weight number, the thinner the thread, so 100 weight thread is thinner than 60 weight. Thread weight can be useful for many different things, including creating lighter weight designs in areas of heavy stitching, or making one denser thread stand out against the rest.

40 weight thread is the most commonly used embroidery thread and will cover most projects, from free-hand embroidery to quilting, digitizing to clothing construction.

Close up of darning foot on Bernina sewing machine

What is the difference in thread fiber?

Thread fiber can make a huge difference for certain projects, but which is right for what?

Cotton has a soft, matte appearance and is very versatile. It can be used on most fabrics, as it is a natural fiber that adjusts easily with fabric changes, such as shrinkage or dying. Cotton is strong and can be used for free-motion, quilting, appliqué and digital machines.

Polyester is a synthetic alternative to cotton. It is strong, smooth and has a greater sheen and stretch than cotton. Polyester is just as versatile and can be used as a stronger alternative in the same projects that cotton is used. It won’t shrink or fade, but over time, polyester threads can cause perishing of cotton fabrics and so is not the first choice for quilters. A cotton/polyester blend can be a great way of achieving the best from both threads.

Often compared to polyester, rayon is semi-synthetic thread that also has its strengths and weaknesses. Rayon thread is highly processed to produce bright colors and a high sheen but is weaker than polyester. This means it is usually chosen for decorative embroideries, rather than for construction (i.e. quilting).

Typically, nylon is characterized as being stronger than polyester, but it melts when ironed and can become brittle over time with laundering. Nylon is a synthetic monofilament that is mostly used when a transparent thread is required.

Free-hand machine embroidery of black cat on calico

How can 40 thread be used?

40 weight thread is the most common used thickness of thread, and therefore, it is the most readily available to buy. This is a general purpose weight that can be used across a whole range of projects. Most sewing machines will have a standard setting that works well with 40 weight thread, as this is classed as a standard weight – including digitized patterns and machines, but this can vary from pattern to pattern.

40 weight thread can be used for free-motion techniques, appliqué, garment construction, quilting, tacking…the list goes on!

Machine embroidered couching of veins and arteries

40 weight thread can also be used in partnership with other threads. For example, machine couching (shown in the above image) requires a heavy thread in the bobbin (e.g. wool) and a lighter thread on top. Metallic threads are another type of thread that work in harmony with 40 weight threads- it can be used on top, but requires a non-metallic bobbin thread of a similar color underneath.

Where do I start?

Personally, I think the best place to start with embroidery is by experimenting! Don’t be afraid to get your machine out and just go for it — trial and error will help you understand your machine and materials in your own time. If that seems a little too daunting why not try some online tutorials? Pinterest is a great place to go for inspiration and Craftsy classes will teach you everything you need to know!

Ready to try one of our online classes but not sure where to begin? Free-Motion Machine Embroidery, Design It, Stitch It: Hand Embroidery and The Machine Embroidered T-Shirt are all great places to start on your journey to mastering the art of the perfect stitch!

What machine embroidery techniques will you use your 40 weight thread with?

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2 Responses to “40 Weight Thread: The Embroidery Mystery Unraveled!”

  1. Marilyn Levings

    What machine embroidery techniques will you use your 40 wt. thread with?

  2. Kayla e Koeppen

    Hello, I am trying to start a denim embroidery-by-hand business. I was wondering what weight thread i should use? This is something i would have asked my mom, however she passed.