General – Rayon and polyester are the most popular embroidery threads available. Always choose the right type of thread for your project as recommended by the designer. Balance your top and bottom thread tension to get best results. Choose a good quality bobbin thread. Breaking thread is a common and annoying problem. Some recommend spraying the thread with a silicon spray to help with this.
Rayon – Rayon is the one of the most favored threads amongst professional embroiderers. It is a soft thread, available in great colors, and suitable for all forms of machine embroidery. Rayon thread holds up well with high-speed stitching without breaking or fraying and it also consistently performs well. It is easily available in many embroidery stores and in a wide range of solid and variegated colors, as well as in a “twist” thread composed of two or more solid colors twisted together to form a single strand. They are available in a light 50wt, standard 40 wt. and a thicker 30 wt. Rayon thread is soft, has a high sheen and is relatively heat resistant but has less elasticity than polyester, is not as colorfast, strong or durable.
Polyester – Polyester embroidery thread is the popular and economical choice. It is available in a wide assortment of colors, and your results will be similar to that of rayon. The benefit of polyester is that it won’t shrink, fade or bleed. Like rayon thread, polyester thread is strong and won’t easily break or fray. Polyester thread is synthetically produced from polymer resins. It can be made with a matte finish to look like cotton, with a medium sheen, or high sheen finish to look like rayon or silk. Trilobal poly is a higher quality polyester with a sheen equal to rayon and is lint free. Due to its strength and color fastness polyester is becoming one of the most popular embroidery threads available these days. There are three types of polyester thread: Spun poly: fiber staples spun together and looks like cotton, Filament poly: continuous fiber and Trilobal poly: high-sheen continuous fiber. Looks like rayon or silk and is lint free.
Nylon – A synthetic thread occasionally used in the form of a monofilament clear thread or as a textured fuzzy (woollie-like) thread. The negatives far outweigh the positives of nylon. Use only with caution. It is very strong with a low melting temperature, is not heat resistant or colorfast – also it becomes brittle through laundering and exposure.
Cotton – The only 100% natural fiber thread made for high speed machines. Cotton has various finishes, each providing specific results. Cotton embroidery thread is very often overlooked by automatic embroidery machine users. But the fact is that it performs beautifully in embroidery machines and has a lovely, soft sheen. Additionally, cotton thread is available in weights up to the very fine 100. Cotton threads are soft and durable and easily adjust to shrinkage. Cotton is a natural fiber and is easy care and available in various thread weights. It is not as strong as polyester, has a low sheen and can be linty.
Mercerized:The thread is treated in a solution, causing the fibers to swell. This allows the dye to better penetrate the fibers and increases the luster of the thread. It also increases the strength of the thread.
Gassed: The thread is passed through a flame at high speed to reduce the fuzz.
Glazed: The thread is treated with wax or other chemicals, then polished to create a higher luster. Although the result is a glossy, hard finish which protects the thread, the glaze does rub off and can gum up the needle and machine. OK for hand quilting but not recommended for machine use.
Cotton-wrapped poly: Most cotton-wrapped poly threads are approximately two-thirds poly and one-third cotton and will therefore resemble the characteristics of poly more than cotton. A mixed-fiber thread is not necessary. If cotton is too weak, use poly. If you’re worried about poly being too strong, use cotton.
Metallic – The quality of metallic thread ranges from very high to very low. A good metallic thread does not require a lubricant. Quality metallic thread has a nylon core. A nylon core offers the most strength and resists tangling. Polyester and rayon cores are inferior. It also has rice paper construction. This adds strength and cohesiveness and makes the thread more soft and supple, reducing the wiry feel. It also reduces tangling. Good metallic threads have an outer coating. Lower quality metallics have no outer coating. This means the metal foil rubs against the needle, creating friction and heat, resulting in discoloring and shredding. A good metallic has an outer coating which reduces friction and acts as a protective layer.
Laminate or flat threads – Produced by bonding layers of polyester together and slicing to a desired width. Available in either 2 ply (weak) or 4 ply (strong) construction. It is colorfast with brilliant, reflective, colors. Can be produced in a hologram effect. Heat-resistant and able to be ironed, it does not require special handling for good results.
Silk threads – absorbs dye more brilliantly than any other fiber, and is truly the top of the line when it comes to specialty threads. It sews smoothly without breaking, and offers the embroiderer the strength of polyester and the stability of cotton. It also has a distinct sheen unmatched by any other thread. Silk threads are available in a variety of sizes and colors, but the 30 to 50 wts. are appropriate for machine embroidery. Silk thread is more costly, but well worth considering.