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Information Topics

About Nomex Thread (TM)
Types of Nomex Thread
Nomex Thread Glossary
Nomex Thread Properties
Nomex Pricing and Supply
How to Save
Alternatives to Filament Nomex
Nomex Thread Spool Sizes
Nominal Spool Weights
Nomex Thread Specifications
About Nomex Thread (TM)
Nomex is a fire retardant thread. It chars at 675 degrees Fahrenheit, and decomposes at 700 degrees Fahrenheit, but never melts. This makes Nomex a great thread for sewing materials that are subject to high heat exposure. Fire retardant is not fire proof. Nomex thread will burn when exposed to a 2500F cigarette lighter. Also, using Nomex thread only makes sense when the fabric is as fire retardant as the Nomex thread.

Types of Nomex Thread
There are several types of Nomex Thread. This page covers information about filament Nomex, which comes in bonded, soft, and Teflon (PTFE) coated finishes. With very few exceptions, filament Nomex is only available in its natural white color. We do have some closeout in other colors, but our replenishment stock will only be available in white. We also carry Spun Nomex, and Nomex Embroidery Thread that are available in basic colors. More details about these items can be found in our Fire Retardant Thread Buying Guide.

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

Bonded
- Bonded Nomex has a protective coating on the thread to resist against fraying and needle friction when it is sewn at higher speeds. Other types of bonded thread we carry are Kevlar, Nylon, and Polyester.

Monocord
- A single ply of Nomex thread that is not sensitive to machine twist direction. It is thinner than regular Nomex thread for reduced stitch appearance. Monocord usually requires a tensioning adjustment. Once it is made, it runs very smooth.

Teflon (PTFE) Coated
- The PTFE coating gives the Nomex thread a slicker texture. It also helps to repel staining, and it is great for hand sewing, reinforcing, and wrapping. It is not recommended for machine sewing or applications that use adhesives. Another type of PTFE coated thread we carry is PTFE Coated Fiberglass Thread.

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

Nomex Thread Properties
To put Nomex thread in perspective, here is a side-by-side comparison of Nomex and three other middleweight (Size 92) threads:
Tensile strength
Nomex:
9 Lbs.

Kevlar: 30 Lbs.
Nylon: 15 Lbs.
Polyester: 15 Lbs.
Stretch before breaking
Nomex:
34%
Kevlar: 2%
Nylon: 26%
Polyester: 26%
Heat decomposition
Nomex:
700F
PTFE Fiberglass: 1022F
Kevlar: 800F
Nylon: 485F
Polyester: 483F
Decomposition - Nomex begins to decompose (turn to ash) at about 700F (371C). Its heat resistance is much higher than nylon or polyester, but lower than Kevlar.
Melting - Nomex thread does not melt. This is important in fire retardant gear.
Elongation - Nomex thread has an average stretch of around 34% over time. This is beneficial for its end use because it allows for the seams to stretch with the fabric, allowing for 'breaking in'.
Acids & Alkalis - Nomex thread is unaffected by most acids, with the exception of some strength loss after long exposure to Hydrochloric, Nitric, and Sulphuric acids. In general, it has good resistance to alkalis.
UV Resistance - Prolonged exposure of Nomex thread to sunlight will cause some strength loss.
Mildew Resistance - Nomex thread has excellent resistance to mildew.
Nomex Thread Information - All Topics

Nomex Pricing and Supply
Compared to other types of thread, Nomex is very expensive. Unfortunately, our newer stock is priced at over $200 per pound. Nomex thread is also subject to large price increases on short notice. We have also experienced times when the supply of Nomex can be very tight, resulting in lengthy lead times - Sometimes exceeding 6 months.

How to Save
Filament Nomex thread is expensive. It should only be used to sew material that has similar qualities. Here are four ways to save:

Buy what you need - Our junior spools in 1 to 4 Ounces are a great value for specific, one-time jobs and hobbyists. They generally ship 1st Class to U.S. addresses so shipping costs are low compared to price.

Choose lighter weights - You get more yards per ounce with lighter weight thread. But, make sure that the thread has the strength you need.

Consider non-standard sizes and closeouts - These threads sell at a big discount compared to our regular thread. We cannot provide certificates of conformance (CERTS) and will probably not restock them in the future.

Nomex Thread Information - All Topics

Alternatives to Filament Nomex
Nomex costs about 5 times more than nylon and polyester, and it is usually only available in white. There are times where other types of thread might be suitable:

Fire Retardant Sewing Thread - Spun Kevlar and spun Nomex threads have about the same fire retardance as Kevlar thread and are available in many colors. This type of thread is the usually the best choice for sewing seams and attaching emblems and logos. These threads look and feel like cotton because they are made by wrapping fiber around a Kevlar or Nomex core.
Information
Fire Retardant Sewing Thread Buying Guide
Shopping
Fire Retardant Sewing Thread

Kevlar Thread - Kevlar begins to decompose (turn to ash) at about 800F (426C). It is only available in its natural pale yellow color. It is much stronger than Nomex, and has very little elasticity.
Information
Kevlar Thread Buying Guide
Shopping
Kevlar Thread

PTFE Coated Fiberglass Thread - PTFE Coated Fiberglass Thread is mostly used in dry filtration and insulation applications. The fiberglass has excellent thermal stability, and can withstand operating temperatures to around 1022 F (550 C). It is important to note the PTFE coating burns away at 620 F (320 C), and is not easy to sew with. It is only available in 3 sizes, and one color.
Information
PTFE Coated Fiberglass Thread Guide
Shopping
PTFE Coated Fiberglass Thread

Cotton Thread - Cotton is not fire retardant, but it does not melt. It chars, then turns to ash similar to Nomex and Kevlar. Its strength is comparable to regular sewing thread.
Information
Aurifil Cotton Thread Buying Guide
Shopping
Aurifil Cotton Thread

Nylon and Polyester Thread - Nylon and polyester thread are not fire retardant. Nylon thread yellows at 300F, sticks at 445F and melts at 500F. Polyester thread sticks at 440F and melts at 483F.
Information
Nylon Thread Buying Guide
Polyester Thread Buying Guide
Shopping
Nylon Thread
Polyester Thread

Nomex Thread Information - All Topics

Nomex Thread Spool Sizes
We sell most of our Nomex thread in 1, 2, 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, and experimenting. Nomex 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.

Spool Dimensions
All of our Nomex 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, ranging from 6.5" to 7.5", but the base dimensions remain constant.
Average Spool Dimensions
1 Oz - Base: 2.5", Height: 4.5"
2 Oz - Base: 2.5", Height: 4.5"
4 Oz - Base: 2.5", Height: 4.5"
Average Spool Dimensions
8 Oz - Base: 3.0", Height: 5.25"
12 Oz - Base: 4.5", Height: 6.5"
16 Oz - 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 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.

Nominal Spool Weights
Industry norms allow Nomex 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 1 Oz Spool
Minimum: 1.3 Oz.
Maximum: 2.5 Oz.
Nominal 2 Oz Spool
Minimum: 2.6 Oz.
Maximum: 4.5 Oz.
Nominal 4 Oz Spool
Minimum: 4.6 Oz.
Maximum: 5.9 Oz.
Nominal 16 Oz Spool
Minimum: 15.6 Oz.
Maximum: 19.9 Oz.
Exception - For Nomex thread that is not on clearance, we narrow the tolerance to 5% due to its exceptionally high cost.
Nomex Thread Information - All Topics

Nomex Thread Specifications
Commercial sizing is most widely used thread size standard. Our Nomex thread shopping selections are listed in commercial sizes. Occasionally we have some off sizes. When this happens, we use the closest Tex Equivalent to the commercial size.
Nomex - Size 46
Commercial Size 46
Tex Equivalent: 40
Gov't Equivalent: B
Average Strength
Pounds  5.0
Kilograms 2.3
Average Thickness
Inches 0.0082 in (82/1000")
Millimeters 0.2083
Needle
Needle Size Range
90/14 to 100/16
Nominal Yards
625 per Ounce
10,000 per Pound
 
Nomex - Size 69
Commercial Size 69
Tex Equivalent: 60
Gov't Equivalent: E
Average Strength
Pounds 7.5
Kilograms 3.4
Average Thickness
Inches: 0.0100 In (10/1000")
Millimeters: 0.25
Needle
Needle Size Range
100/16 to 110 /18
Nominal Yards
438 per Ounce
7,000 per Pound
 
Nomex - Size 92
Commercial Size 92
Tex Equivalent: 80
Gov't Equivalent: F
Average Strength
Pounds 9.0
Kilograms 4.1
Average Thickness
Inches: 0.0116 In (12/1000")
Millimeters: 0.29
Needle
Needle Size Range
110/18 to 125/20
Nominal Yards
 313 per Ounce
 5,000 per Pound
 
Nomex - Size 138
Commercial Size 138
Tex Equivalent: 120
Gov't Equivalent: FF
Average Strength
Pounds 14.0
Kilograms 6.4
Average Thickness
Inches: 0.0142 (14/1000")
Millimeters: 0.36
Needle
Needle Size Range
125/20 to 140/22
Nominal Yards
200 per Ounce
3,200 per Pound
 
Nomex - Size 207
Commercial Size 207
Tex Equivalent: 180
Gov't Equivalent: 3-Cord
Average Strength
Pounds 16.0
Kilograms 7.3
Average Thickness
Inches: 0.0174 (17/1000")
Millimeters: 0.44
Needle
Needle Size Range
140/22 to 180/24
Nominal Yards
144 per Ounce
2,300 per Pound
 
Nomex - Size 277
Commercial Size
Tex Equivalent: 240
Gov't Equivalent: 4-Cord
Average Strength
Pounds 24.0
Kilograms 10.9
Average Thickness
Inches: 0.0201 (20/1000")
Millimeters: 0.51
Needle
Needle Size Range
180/24 to 220/26
Nominal Yards
113 per Ounce
1,800 per Pound
 
Nomex - Size 346
Commercial Size 346
Tex Equivalent: 300
Gov't Equivalent: 5-Cord
Average Strength
Pounds 30.0
Kilograms 13.6
Average Thickness
Inches: 0.0225 (22/1000")
Millimeters: 0.57
Needle
Needle Size Range
230/26 to 260/28
Nominal Yards
88 per Ounce
1,400 per Pound
 
Nomex - Size 415
Commercial Size 415
Tex Equivalent:
Gov't Equivalent: 6-Cord
Average Strength
Pounds 36.0
Kilograms 16.3
Average Thickness
Inches: 0.0247 (25/1000")
Millimeters: 0.63
Needle
Needle Size Range
280/28 to 330/30
Nominal Yards
69 per Ounce
1,100 per Pound
 
Nomex - Size 554
Commercial Size 554
Tex Equivalent:
Gov't Equivalent: 8-Cord
Average Strength
Pounds 44.4
Kilograms 20.1
Average Thickness
Inches: 0.0310 (31/1000")
Millimeters: 0.79
Needle
Needle Size Range
330/30 to 360/32
Nominal Yards
58 per Ounce
930 per Pound
 
Nomex Thread Information - All Topics