Embroidery thread types: polyester, rayon, cotton, metallic and specialty

Thread types at a glance

Weights are covered on their own page: see thread weights. Everything below assumes the standard 40 wt unless noted.

Polyester: the default for most embroiderers

Embroidery polyester is usually a continuous filament thread (long, smooth fibers rather than short spun staple), which is why it shines and sheds very little lint. It stands up to chlorine bleach, hot washes and industrial laundering better than rayon, so it is the standard for uniforms, towels, kids' clothing and anything a customer might bleach.

Modern embroidery polyesters are made to imitate the sheen of rayon closely, and at arm's length most people cannot tell them apart. They also tolerate high speeds on multi-needle machines well. Common brands include Isacord, Madeira Polyneon, Robison-Anton polyester and Gunold Poly, along with many store and machine-maker brands.

Watch for: polyester has some stretch. If the top tension is set high, it can stretch during stitching and recover afterward, pulling fabric in. Keep tension at a balanced I-test setting and use enough stabilizer.

Rayon: the traditional luster

Rayon is a regenerated cellulose fiber. It was the standard embroidery thread for decades and still has a following for its soft, deep luster and the way it lies down in satin stitches. It is softer to the touch than polyester, which some people prefer for items worn against the skin.

Watch for: rayon is weaker than polyester, especially when wet, and chlorine bleach can damage or fade it. It is more prone to breaking at high speed or in very dense designs. If you see more breaks with rayon than with polyester on the same design, slow down a step before changing anything else. The polyester vs rayon comparison goes deeper.

Cotton: matte and natural

Cotton embroidery threads, often 50 wt or 30 wt for machine work, give a flat, hand-made look that suits quilts, redwork and vintage styles. Because cotton is a spun staple fiber, it sheds lint, so clean the bobbin area and tension discs more often when you use it. It also has less sheen to hide small coverage gaps, so it may need slightly denser stitching or a heavier weight.

Metallic and holographic threads

Wrapped metallics have a core (often polyester or nylon) wrapped with a thin metallized foil. Flat holographic or film threads are a thin slit ribbon of metallized polyester. Both add drama and both demand care: slower speed, lower top tension, a needle with a larger eye, and designs that are not too dense. Flat film threads need to come off the spool without twisting, usually from a vertical spool pin. The full routine is on the metallic thread page.

Specialty threads

• Variegated. Color changes along the length. The repeat interval interacts with stitch length, so the effect looks different on satins and fills. Test first.
• Glow-in-the-dark. Usually stiffer and less smooth than standard polyester; treat it like a metallic: slower, lower tension, larger eye.
• Heavy decorative (12 wt and up). Needs a large needle, often 100/16, and designs digitized with fewer, longer stitches. A standard design stitched in 12 wt will be overloaded.
• Wool blends. Fuzzy and soft, with a large needle and low density.
• Water-soluble basting thread. Not decorative, but handy for temporary basting that disappears when rinsed.

Bobbin thread is a different product

The thread on the back of the design is usually not the same as the top. Most embroiderers use a dedicated bobbin thread in white or black, typically 60 wt or 90 wt polyester (spun or filament), which keeps the back flat and lets the bobbin last longer. See bobbin thread and prewound bobbins.

How to choose: a decision order

1. How will it be washed? If bleach, industrial laundering or frequent hot washing are possible, choose polyester.
2. What finish do you want? Bright sheen: polyester or rayon. Matte: cotton. Glint: metallic.
3. What weight does the design expect? Most commercial designs are made for 40 wt. A heavier or finer thread needs a design built or adjusted for it.
4. Which color line do you own? Staying in one brand makes color matching and software palettes easier; see thread color conversion.
5. How does your machine run it? If a thread breaks repeatedly at your normal speed after the needle and threading are right, try a different brand or fiber before redesigning the job.

Thread quality and storage

A good embroidery thread is evenly twisted, has no slubs, and feeds without twisting back on itself. Cheap threads vary in thickness along the spool, which shows up as patchy coverage and uneven tension. Signs of a thread problem, as opposed to a machine problem:

• Breaks with one spool but not another of the same type, on the same design.
• Thread that kinks into curls as it leaves the spool.
• Thread that snaps easily when you tug a length between your hands, compared with a fresh spool.

Store thread covered and out of sunlight. Light fades dyes and weakens fibers on the outer layers. Very dry, heated rooms can make some threads brittle. If an older spool breaks constantly, unwind and discard the outer few meters and test again. For break diagnosis in general, see thread breaking and thread shredding.

Spool types and how they feed

Spool winding affects how thread leaves the spool. Cross-wound spools (thread laid diagonally in an X pattern) generally feed best off the top of the spool, from a horizontal pin or a stand. Stacked or parallel-wound spools, with thread laid in straight rows, generally feed best off the side, from a vertical pin so the spool can turn. Large cones on multi-needle machines feed from a stand above the machine. Getting this wrong adds twist and drag that looks like a tension problem. For setups with cone stands, see thread stands and delivery.