Information Topics

Polyester Thread Buying Guide

Polyester thread looks, feels, and sews like nylon. You cannot tell the difference just by looking, and technical specifications like strength and stretch are very similar. This means that polyester works just as well as nylon in most applications including: upholstery, leatherwork, automobiles, banners and flags, sports gear, dog collars, horse saddles and tack, knife sheaths, gun holsters, fishing lures, and brief cases.

This guide specifically talks about industrial polyester thread, also known as filament polyester, or bonded polyester thread. There are other types of thread that are made of polyester including:
 
Embroidery Thread - We have many polyester embroidery threads on our Embroidering, Quilting, and Sewing Thread page featuring the Robison-Anton Super Brite Polyester in about 400 colors.
 
Spun Polyester - Much of the thread used for sewing garments is spun polyester sold under the names Maxi Lock and Excell. They look, feel, and sew like cotton. They are widely known as general purpose threads.

Selecting Polyester Thread

• Polyester Thread Glossary - The polyester thread glossary covers common terms used with polyester thread.
• Polyester Thread Uses - Where using polyester thread works best.
• Polyester Thread Limitations - Where other types of thread may be better suited than polyester.

Polyester Thread Properties

• Normal Wear and Tear - Topics cover elongation over time, mildew, aging, UV, abrasion, and heat resistance.
• Chemical Resistance - Explains how polyester reacts to cleaning and other chemicals.

Polyester Thread Sizing

• Overview - Considerations for selecting the right size polyester thread.
• Size Descriptions - Use the polyester by size description summary to determine machine capability, stitch visibility, and needle to thread size.
• Specifications - Covers equivalent size standards, strengths, thicknesses, and yards per pound.
• Thread Size to Material - Recommended thread sizes for fabric and leather.

Polyester Thread Spool Sizes

• Nominal Spool Weights - Covers maximum and minimum allowances for thread per spool.
• Spool Dimensions - Covers spool sizes, and options for using larger spools.

Selecting Polyester Thread

With polyester thread selection, understanding terminology, uses, limitations, and sizes are some of the most important considerations in order to ensure the best choice possible.

Polyester Thread Glossary

Bonded - Bonded polyester has a protective coating on the thread to resist against fraying, needle friction and heat when it is sewn at higher speeds. Bonding also helps to prevent unraveling. It is important to note that colors of bonded threads appear slightly darker on the spool. Colors will become lighter when sewn. Other types of bonded thread we carry are Nylon, Nomex, and Kevlar.

Soft - A polyester thread that is not bonded. It is suitable for sewing at slower speeds. It is better suited for gluing applications, because bonded coatings repel glues and adhesives.

Left Twist - The standard ply twist direction for almost every single-needle machine on the market. It is widely known as a Z-Twist, or Standard Twist. All of our thread is left twist unless otherwise noted.

Right Twist - This is widely known an S-Twist, and sometimes a Reverse Twist. It is more commonly used in double needle machines for banners.

Monocord - A single ply of polyester thread that is not sensitive to machine twist direction. It is about 10 to 14% stronger. But, it is thinner than regular polyester for reduced stitch appearance. Monocord usually requires a tensioning adjustment. Once it is made, it runs very smooth. Enhanced UV rated Polyester is more often available in monocord.

Size - A number designation given to a threads thickness, based on weight. We carry eleven different sizes from the ultra-thin Size 15, to the ultra-thick Size 554. The most popular size is Size 69. There are 3 main size standards: Commercial, Tex, and Government. Our product listings use commercial sizing. Our Specifications chart shows equivalent sizing.

Putup - Putup refers to the amount of thread on a spool. Commercial sewers generally by Polyester thread by the pound; hobbyists and casual sewers can save with our two and four ounce spools.

Non Wicking - Non wicking thread is treated to prevent water absorption. This is helpful when you are sewing things that are left outdoors. But, it only helps if the fabric is also water repellant. Non-wicking polyester thread may shred at faster speeds, and may also require a tensioning adjustment.

Polyester Thread Uses

Polyester does better than nylon when you are sewing things that have prolonged exposure to sunlight (UV rays) and moisture. This means it is a better choice for sewing anything that is going to be used outdoors most of the time. It is important to distinguish between prolonged and occasional use. For example, a tent used for annual camping trips can be sewn with either nylon or polyester; a tent used to house a field operation for a season should be sewn with polyester.

Polyester thread has excellent UV resistance, but it does not provide the ultimate UV resistance. Pricey, plastic-looking brands like Sunbrella and Tenara that come with replacement guarantees will outperform regular polyester. Also, there are enhanced UV treated polyester and nylon threads that do better. None of this matters if the material sewn is not equally bleach and sunlight resistant. After all, the material makes up at least 90% of the content and cost of the item that is being sewn.

Uses for polyester thread include: auto and marine covers, awnings, banners, boats, bookbinding, carpets, convertible tops, covers, curtains, hammocks, leatherwork, luggage, motorcycle seats and saddle bags, patio furniture, pet accessories, sails, shade Structures, Snowmobiles, and Tents.

Polyester Thread Limitations

Polyester thread is popular because of its weather resistance, versatility, durability, and strength to size. There are applications where other types of thread may be better suited, depending on the conditions the end use will be under. Here are some of the most notable circumstances.

Fire retardant garments and gear - Polyester thread sticks at 440F and melts at 483F. This is too low for any application where thread and material must withstand high temperatures. Use Kevlar, Nomex, and PTFE Fiberglass threads in these situations. Kevlar and Nomex are heat resistant to at least 600F and do not melt; PTFE fiberglass protects to 1,000F.

Critical need for strength - Polyester thread is strong enough for the kinds of applications described so far. But, it is a bad choice for high stress applications such as conveyer belts because it can stretch up to 26% before it breaks. Size-for-size, Kevlar Thread is about twice as strong and much more expensive than nylon or polyester. For example, Size 92 polyester has a 14.5 pound tensile strength; Kevlar in that size has a 30 pound tensile strength. Also, Kevlar only stretches 2% before it breaks.

Cotton-like look - Our polyester thread has a smooth, glossy, shiny finish that does not go well with garments that need a soft, fuzzy, cotton-like look. In these cases, Cotton, Spun Polyester, and Wooly Nylon are better and less expensive choices.

Clear, or Invisible Stitching - Related Category: Monofilament Thread. Monofilament is made from nylon, and its construction is similar to fishing line.

Polyester Thread Properties

Normal Wear and Tear

 Elongation - Polyester thread stretches about 26% over time. This is beneficial for its end use, because it allows for the seams to stretch with the fabric, allowing for 'breaking in'. For active wear and lighter materials, Woolly Nylon thread has a greater stretch. Kevlar Thread has about a 2% stretch.

Mildew, Aging, and Abrasion - Polyester thread has excellent resistance to mildew, aging, and abrasion.

Heat - Polyester thread begins to stick at approximately 440F, and melt at around 483F.

Chemical Resistance

Bleaches - In general, polyester thread has excellent resistance to bleaches and other oxidizing agents.

Acids and Alkalis - Polyester thread has excellent resistance to most acids, but it will dissolve with partial decomposition in concentrated solutions of sulfuric acids. It has a fair resistance to alkalis.

Hydrocarbons - Polyester thread has excellent resistance to hydrocarbons such as gasoline, Diesel, and kerosene.

Polyester Thread Sizing

Overview

Thread size is important because there are many considerations. The main ones are:

• Machine Capability - Home, commercial and heavy duty sewing machines have different thread and needle size limitations.
• Needle Size - Needles have sizes that are best suited for specific thread sizes and machine types.
• Stitch Appearance - Are you looking for stitching to be inconspicuous, noticeable, very noticeable, or to be a focal point?
• Strength - Is the thread a suitable strength for what is being sewn?

When polyester thread's size increases...

• Commercial and Tex Equivalent numbers increase.
• Machine capability requirements increase.
• Thread diameter increases.Thread strength increases.
• Needle size increases.
• Needle heat and friction increase.
• Stitch visibility increases.
• Fabric ounce per yard increases.
• Leather ounce per yard increases.
• Yards per pound decreases.

Polyester Thread Size Descriptions

Use the polyester thread by size description chart to determine machine capability. Home, commercial and heavy duty sewing machines have different thread and needle size limitations. This chart also describes in general way, the level of stitch visibility, and notes that are relevant to size.

Polyester - Size 15
Size 15 (Tex 16) Polyester is an ultra lightweight thread used on home and commercial machines with a size 70/10 to 80/12 needle. Its stitch appearance is inconspicuous. All size 15 items are soft, and on clearance. Alternatives may be available in Nylon, Cotton and Spun Polyester.

Polyester - Size 33
Size 33 (Tex 30) Polyester is a lightweight thread used on home and commercial machines with a size 80/12 to 90/14 needle. Its stitch appearance is inconspicuous. Most manufacturers have either discontinued size 33 polyester. The ones that still manufacture it have very high minimums, and very expensive pricing. We no longer carry it as standard stock, but special orders at manufacturer minimums may be possible with very long lead times. We carry Size 33 Nylon Thread as an alternative, and expanded our color selection.

Polyester - Size 46
Size 46 (Tex 45) Polyester is a lightweight thread used on home and commercial machines with a size 90/14 to 100/16 needle. Its stitch appearance is inconspicuous. It is available in about 40 colors.

Polyester - Size 69
Size 69 (Tex 70) is a middleweight thread used on home and commercial machines with a size 100/16 to 110 /18 needle. Its stitch appearance is inconspicuous, becoming more noticeable. It is the thickest size most home sewing machines can handle, and it is available in over 50 colors.

Polyester - Size 92
Size 92 (Tex 90) is a middleweight thread used on commercial machines with a size 110/18 to 125/20 needle. Its stitch appearance is noticeable. Most people cannot break a size 92 Polyester by hand. It is available in over 50 colors.

Polyester - Size 138
Size 138 (Tex 135) is a middle to heavyweight thread used on commercial and heavy duty machines with a size 125/20 to 140/22 needle. Its stitch appearance is noticeable, beginning to stand out. It is available in about 50 colors.

Polyester - Size 207
Size 207 (Tex 210) is a heavyweight thread used on commercial and heavy duty machines with a size 140/22 to 180/24 needle. Its stitch appearance stands out. It is available in mostly basic colors.

Polyester - Size 277
Size 277 (Tex 270) is a heavyweight thread used on commercial and heavy duty machines with a size 180/24 to 220/26 needle. Its stitch appearance stands out, becoming more of a focal point. It is available in very basic colors.

Polyester - Size 346
Size 346 (Tex 350) is a heavyweight thread used on heavy duty machines with a size 220/26 to 260/28 needle. Its stitch appearance is a focal point. It is available in black, white, brown, and in some closeout colors.

Polyester - Size 415
Size 415 (Tex 410) is a heavyweight thread used on heavy duty machines with a size 260/28 to 330/30 needle. Its stitch appearance is a focal point. It is available in black and white.

Polyester - Size 554
Size 554 (Tex 600) is an ultra heavyweight thread used on heavy duty machines with a size 330/30 to 360/32 needle. Its stitch appearance is a focal point. It is available in black and white, and is about 1 mm thick.

Polyester Thread Specifications

Polyester - Size 15

• Commercial Size 15, Tex 16 (T-16), Gov't Size 00
• Average Strength 1.5 Lbs. (0.7 kg)
• Average Thickness 5/1000" (0.005 in.), or 0.13 mm
• Recommended Needle Sizes 70/10 to 80/12
• Average Yards 1750 per ounce (28,000 per Pound)

Polyester - Size 33

• Commercial Size 33, Tex 30 to 35 (T-30 to T-35), Gov't Size AA, Tkt 80
• Average Strength 3.0 Lbs. (1.4 kg)
• Average Thickness 7/1000" (0.007 in.) or, 0.18 mm
• Recommended Needle Sizes 80/12 to 90/14
• Average Yards 850 per ounce (13,800 per Pound)

Polyester - Size 46

• Commercial Size 46, Tex 45 (T-45), Gov't Size B, Tkt 60
• Average Strength 7.0 Lbs. (3.2 kg)
• Average Thickness 8/1000" (0.008 in.) or, 0.20 mm
• Recommended Needle Sizes 90/14 to 100/16
• Average Yards 625 per ounce (10,000 per Pound)

Polyester - Size 69

• Commercial Size 69, Tex 70 (T-70), Gov't Size E, Tkt 40
• Average Strength 11.0 Lbs. (5.0 kg)
• Average Thickness Inches 11/1000" (0.011 in..) or, 0.28 mm
• Recommended Needle Sizes 100/16 to 110 /18
• Average Yards 375 per ounce (6,000 per Pound)

 Polyester - Size 92

• Commercial Size 92, Tex 90 (T-90), Gov't Size F, Tkt 30
• Average Strength 14.5 Lbs. (6.6kg)
• Average Strength 14.5 Lbs. (6.6 kg)
• Average Thickness Inches 12/1000" (0.012 in) or, 0.31
• Recommended Needle Sizes 110/18 to 125/20
• Average Yards 263 per ounce (4,200 per Pound)

Polyester - Size 138

• Commercial Size 138, Tex 135 (T-135), Gov't Size FF, Tkt 20
• Average Strength 21.0 Lbs. (9.5 kg)
• Average Thickness Inches 15/1000" (0.015 in.) or, 0.38 mm
• Recommended Needle Sizes 125/20 to 140/22
• Average Yards 187 per ounce (3,000 per Pound)

 Polyester - Size 207

• Commercial Size 207, Tex 210 (T-210), Gov't Size 3 Cord (3/C) Tkt 15
• Average Strength 31.0 Lbs. (14.0 kg)
• Average Thickness Inches 19/1000" (0.019 in.) or, 0.48 mm
• Recommended Needle Sizes 140/22 to 180/24
• Average Yards 187 per ounce (2,100 per Pound)

 Polyester - Size 277

• Commercial Size 277, Tex 270 (T-270), Gov't Size 4 Cord (4/C), Tkt 10
• Average Strength 44.0 Lbs. (20.0 kg)
• Average Thickness Inches 23/1000" (0.023 in.) or, 0.58 mm
• Recommended Needle Sizes 180/24 to 220/26
• Average Yards 93 per ounce (1,496 per Pound)

Polyester - Size 346

• Commercial Size 346, Tex 350 (T-350), Gov't Size 5 Cord (5/C)
• Average Strength 53.0  Lbs. (24.0 kg)
• Average Thickness Inches 26/1000" (0.026 in.) or, 0.66 mm
• Recommended Needle Sizes 220/26 to 260/28
• Average Yards 75 per ounce (1,200 per Pound)

Polyester - Size 415

• Commercial Size 415, Tex 410 (T-410), Gov't Size 6 Cord (6/C)
• Average Strength 73.0 Lbs. (33.0 kg)
• Average Thickness Inches 28/1000" (0.028 in.) or, 0.71 mm
• Recommended Needle Sizes 260/28 to 330/30
• Average Yards 65 per ounce (1,040 per Pound)

Polyester - Size 554

• Commercial Size 554, Tex 600 (T-600), Gov't Size 8 Cord (8/C)
• Average Strength 98.0 Lbs. (44.0 kg)
• Average Thickness Inches 33/1000" (0.033 in.) or, 0.84 mm
• Recommended Needle Sizes 330/30 to 360/32
• Average Yards 41 per ounce (656 per Pound)

Thread Size to Material

The material that you are sewing costs far more than the thread. In most cases, it is better for the thread to break than to have the stitches pull through the fabric. This means that the weight of the fabric, in ounces per square yard, is the best way to determine thread size. Here are size recommendations for fabric and leather.

Fabric Ounce to Yard and Thread Size Range

2 to 6 Ounce Fabric: Polyester Thread Sizes 15 to 33
6 to 8 Ounce Fabric: Polyester Thread Sizes 33 to 46
8 to 10 Ounce Fabric: Polyester Thread Sizes 69 to 92
12 to 14 Ounce Fabric: Polyester Thread Sizes 92 to 207
Comments
There other things to consider. You may use a thinner thread because your machine cannot handle a heavier thread, if it does not compromise safety. Or, you may choose a thicker thread because you want stitches to stand out. Selecting specific needle points designed for specific materials is recommended if a universal, round point needle won't suffice.

Leather Ounce to Yard and Thread Size Range

2 to 3 Ounce Leather: Polyester Thread Sizes 33 to 69
3 to 4 Ounce Leather: Polyester Thread Sizes 46 to 92
4 to 5 Ounce Leather: Polyester Thread Sizes 69 to 138
5 to 6 Ounce Leather: Polyester Thread Sizes 92 to 207
7 to 8 Ounce Leather: Polyester Thread Sizes 138 to 277
8 to 9 Ounce Leather: Polyester Thread Sizes 207 to 554
Multiple Layers of Leather: Polyester Thread Sizes 207 to 554
Comments
There other things to consider. You may use a thinner thread because your machine cannot handle a heavier thread, if it does not compromise safety. Or, you may choose a thicker thread because you want stitches to stand out.

Polyester Thread Spool Sizes

We sell most of our polyester thread in 4 and 16 Ounce (1 Pound) spool sizes or putups. The smaller putups cost more per ounce than the larger ones. But, they are a better choice for one-time jobs, casual sewing, people who need a stash of many colors, and experimenters. Polyester thread is sold by weight (ounces, pounds) - not yards. This is because the number of yards-per-pound decreases as thread thickness increases. Selling by weight means prices for a given size spool are about the same across most thread sizes.

Nominal Spool Weights

Industry norms allow nylon thread spool weights to vary by plus/minus 10% from the stated nominal weight. This means that customers get slightly less or slightly more thread than the nominal weight shown on our site. This chart shows our nominal weights and the thread-weight range ( including the spool's weight ) for various sizes. When spools fall within these ranges, we do not charge for when they go over or refund for when they go under. It is important to note that we usually do not charge when a spool goes over the maximum tolerance, but we will always refund when they go below the tolerance.

Nominal 2 Oz Spool - Minimum Spool Weight: 2.6 Oz., Maximum Spool Weight: 4.5 Oz.
Nominal 4 Oz Spool - Minimum Spool Weight: 4.6 Oz., Maximum Spool Weight: 5.9 Oz.
Nominal 6 Oz Spool - Minimum Spool Weight: 6.0 Oz., Maximum Spool Weight: 7.9 Oz.
Nominal 8 Oz Spool - Minimum Spool Weight: 8.0 Oz., Maximum Spool Weight: 10.5 Oz.
Nominal 12 Oz Spool - Minimum Spool Weight: 10.6 Oz., Maximum Spool Weight: 15.5 Oz.
Nominal 16 Oz Spool - Minimum Spool Weight: 15.6 Oz., Maximum Spool Weight: 19.9 Oz.

Spool Dimensions

All of our polyester thread is wound on king spools unless otherwise noted. Most of our 2 and 4 ounce spools are wound in-house, and the spool sizes are consistent for those. Normally, manufacturer spool dimensions are consistent. There are some times one-off occasions where manufacturers will wind 12 and 16 ounce spools with different heights, but the base dimensions remain constant.

Average Spool Dimensions
2 and 4 Oz Spools - Base: 2.5", Height: 4.5"
6 and 8 Oz Spools - Base: 3.0", Height: 5.25"
12 and 16 Oz Spools By Brand
A&E (Anefil Poly) - Base: 4.5", Height: 7.5"
Amann USA (Serabond) - Base: 4.5", Height: 7.5"
Ozen (PolyArt) - Base: 4.5", Height: 6.5"
Eddington - Base: 4.5", Height: 6.5"
Fil-Tec (Premofast) - Base: 4.5", Height: 7.5"
Service Thread - Base: 4.5", Height: 6.5"
Inside Diameter
The inside shaft diameter of all spools
described, regardless of base and height,
is 1 inch.
Comments
For sewing machines not geared to handle these size spools, a Thread Cone Holder may be needed. It is designed to help machines bypass these limitations. There are also DIY thread cone holders that are can be made from PVC pipe, wire coat hangers, or coffee cups most notably. The advantage of a thread cone holder is that it is specifically designed for sewing.
We also carry 100 yard and 50 yard Hand Stitching Tubes. They are not particularly designed for machine sewing, but customers have created Do-It-Yourself adaptors.
It is important to note that DIY projects can cause machine damage or create tensioning issues if not made properly.