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Information Topics

Fire Retardant Thread Buying Guide
Fire Retardant Sewing Thread Uses
Fire Retardance
Spun Kevlar and Nomex
Fire Retardant Sewing Thread Properties
Children's Garments
Specifications
Spun Kevlar
Spun Nomex

Related Information Pages
Kevlar Thread Buying Guide
Nomex Thread Buying Guide

PTFE Coated Fiberglass

Shopping Selections
Fire Retardant Sewing Thread
Fire Retardant Embroidery Thread
Fire Retardant Embroidery Bobbins
Kevlar Thread
Nomex Thread

PTFE Coated Fiberglass Thread

 
Fire Retardant Thread Buying Guide
Fire retardant sewing thread is used with clothing and gear designed to protect from fire and heat. This Fire Retardant Sewing Thread Buying Guide helps customers get the right thread for their needs. Our approach is to explain fire retardant thread uses, what "fire retardance" means, the differences between spun Kevlar(TM) and spun Nomex(TM), and give specifications for both threads.

Fire Retardant Sewing Thread Uses
Use this thread for sewing clothing and gear for first responders, motor sports participants, military, and others who need protection from fire and heat. It should only be used with fabrics and materials that have the same level of fire retardance. This thread is expensive and using it for regular sewing is wasteful.

Use lighter weight threads, Tex 27 to 50, for sewing seams and attaching patches to garments. Use the heaver weight, Tex 60 and higher, for sewing gear where thread strength is important. Regular Kevlar and Nomex thread would give similar levels of fire retardance. But they would not look attractive.

Fire Retardance
With the exception of most clearance items, our fire retardant thread is UL approved and meet these standards. NFPA 1975-1999, NFPA 1971-1997, NFPA 1976-1992, and NFPA 1977-1998. More simply put, they do not melt and can withstand temperatures of 700F (366C) before they decompose. This compares to a 450F (218C) melt point for general purpose threads such as Nylon and Polyester. Fire retardant is not fire-proof. These threads will burn when exposed to a 2500F (1357C) cigarette lighter. They should not be used with conveyer belts and other gear that operates above 700F.

Spun Kevlar and Nomex
Fire retardant threads are made by wrapping a thin Kevlar and Nomex in an outer layer of cotton. This gives the thread a fuzzy texture, cotton-like look, and lets it be dyed any color. Spun Kevlar and Nomex are not as strong as their regular counterparts. In the lighter weights, the differences are not important because both threads are strong enough for seams and patches. In the heavier weights, strength often matters and Kevlar is usually the better choice.

Fire Retardant Sewing Thread Properties
Decomposition - Fire retardant sewing thread begins to decompose (turn to ash) at about 700F (426C). Much higher than nylon or polyester.

Melting - Fire retardant sewing thread does not melt. This is important in fire retardant gear.

Mildew, Aging, Sunlight, and Abrasion - Excellent resistance to mildew and aging. Prolonged exposure to sunlight causes deterioration. Polyester thread works just as well in some cases. Abrasion - Good abrasion resistance.

Children's Garments
The U.S. and other countries require children's clothing to be made with fire resistant thread that withstands temperatures up to 450F. There are much less expensive cotton threads that may meet this requirement.
Information
Aurifil Cotton Thread Buying Guide
Shopping
Aurifil Cotton Thread
Specifications

Spun Kevlar Specifications
Mil Spec A-A-55195

Spun Kevlar - Tex 35

Average Strength
Pounds: 6.40
Kilograms: 2.90

Needle
Needle Size Range
80/12 to 90/14

Nominal Yards
781 per Ounce
12,500 per Pound

 

Spun Kevlar - Tex 50

Average Strength
Pounds: 11.20
Kilograms: 5.08

Needle
Needle Size Range
90/14 to 100/16

Nominal Yards
500 per Ounce
8,000 per Pound

 

Spun Kevlar - Tex 70

Average Strength
Pounds: 14.20
Kilograms: 6.44

Needle
Needle Size Range
100/16 to 110 /18

Nominal Yards
375 per Ounce
6,000 per Pound

Tex 70 is the thickest size most home sewing machines can handle.

 

Spun Kevlar - Tex 90

Average Strength
Pounds: 19.30
Kilograms: 8.75

Needle
Needle Size Range
110/18 to 125/20

Nominal Yards
300 per Ounce
4,800 per Pound

 

Spun Nomex Specifications
Mil Spec A-A-552117A

Spun Nomex - Tex 27
Average Strength
Pounds: 1.60
Kilograms: 0.73

Needle
Needle Size Range
70/10 to 80/12

Nominal Yards
1231 per Ounce
19,700 per Pound

Tex 27 is available in Fire Retardant Embroidery Thread in about 15 colors. It is a 40 weight embroidery thread. Fire Retardant Sewing Thread is also available in limited closeout colors. They have slightly different constructions. The fire retardant sewing thread is for light duty seam reinforcement, and is usually not suitable for embroidery.

Spun Nomex - Tex 35
Average Strength
Pounds: 2.00
Kilograms: 0.91

Needle
Needle Size Range
80/12 to 90/14

Nominal Yards
850 per Ounce
13,600 per Pound

Spun Nomex - Tex 40
Average Strength
Pounds: 2.60
Kilograms: 1.18

Needle
Needle Size Range
80/12 to 90/14

Nominal Yards
688 per Ounce
11,000 per Pound

Spun Nomex - Tex 50
Average Strength
Pounds: 3.00
Kilograms: 1.36

Needle
Needle Size Range
90/14 to 100/16

Nominal Yards
600 per Ounce
9,600 per Pound

Spun Nomex - Tex 70
Average Strength
Pounds: 4.50
Kilograms: 2.04

Needle
Needle Size Range
100/16 to 110 /18

Nominal Yards
444 per Ounce
7,100 per Pound

Tex 70 is the thickest size most home sewing machines can handle.

Spun Nomex - Tex 90
Average Strength
Pounds: 5.50
Kilograms: 2.49

Needle
Needle Size Range
110/18 to 125/20

Nominal Yards
325 per Ounce
5,200 per Pound


Fire Retardant Thread Buying Guide - All Topics