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Overview - Nature’s Reinforcing Material
Unlike some manufacturers, Globe views leather as a true miracle material for
the firefighter, based on extensive testing cycles in the Globe lab over
several years. Leather is unique. It has a physical structure composed of
millions of coil-like molecules built into tiny fibrous strands. These strands
are twisted together to form bundles which interweave themselves into a 3-dimensional
configuration. The bundles, in turn, form an intricate, dense, fiber network
with innumerable interlocks providing no easy path for a tear to follow.
The result is leather’s very high tensile strength. Synthetic fibers
are manufactured with threads running in an orderly manner in both the warp
(W) and fill (F) directions. Tear strength is directly affected by the total
number of threads, which frequently form a path of least resistance. A tear,
once started, follows the path of least resistance. The Tear Strength Chart
below illustrates this.
| TEAR STRENGTH |
| MATERIAL |
NFPA REQUIREMENT |
WARP |
FILL |
| 7.5 oz. NOMEX® |
22 lbs. |
55.8 |
33.7 |
| 7.5 oz. Pbi® |
22 lbs. |
49.0 |
41.7 |
| ADVANCE® |
22 lbs. |
42.5 |
29.6 |
| LEATHER |
None |
35.8 lbs. |
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Leather, More Flame Resistant
NFPA 1971, 1997 Revision, included leather in its flame resistance requirement.
This testing was not new to Globe, since our lab routinely performs QC and
flame tests on all incoming fabrics, including leather used as a Globe turnout
reinforcement. The NFPA Flame Test is based on Federal Test Method Standard
No. 191A, Method 5903, Flame Resistance of cloth, and subjects the material
to a 12-second vertical flame exposure, followed by after flame and char
length measurements. Five samples are tested in both Warp and Fill directions
with a 4” maximum char length and 2-second maximum after flame allowed.
The readings below are normal averages.
| FLAME RESISTANCE |
| MATERIAL |
WARP |
FILL |
AFTER FLAME |
| 7.5 oz. NOMEX® |
3.2" |
2.8" |
< 1 second |
| 7.5 oz. Pbi® |
.6" |
.6" |
0 seconds |
| ADVANCE® |
.9" |
.6" |
< 1 second |
| LEATHER |
.4" |
.5" |
< 1 second |
Leather, More Thermal Resistant
Southern Mills and North Carolina State University School of Textiles, who
perform the majority of Globe’s TPP testing, both agree that leather
alone can yield a TPP rating of 35 as required by NFPA. (Note: leather comes
in different grades and weights; the results above are based on the premium
quality that Globe offers as standard.) Since TPP testing is essentially
a function of thickness, leather’s superior thermal resistance due
to its greater density is obvious. On this sometimes controversial issue,
third party testing shows, and Globe concurs, that leather provides more
thermal protection than a single layer of any Outer Shell fabric offered
today.
Leather, More Puncture Resistant
If you have access to any old John Wayne westerns in the station house, there’s
another lesson to be learned about leather - its high puncture and abrasion
resistance - whether the wearer is in the saddle herding cattle or in a physical
encounter in the local saloon. Its unique structure, the random weaving of
thousands of fibers, renders it more puncture and abrasion resistant than any
synthetic textile available for protective clothing today. Why do you suppose
most good gloves are leather? Or why motorcycle racers insist on leather outer
clothing?
Leather, More Chemical Resistant
The process of tanning converts the raw collagen fibers of a hide into a uniform
product that is not susceptible to rotting and less prone to attack from
mildew or bacteria. In fact, many of the tanning chemicals significantly
enhance leather’s natural properties - its dimensional stability, resistance
to abrasion, chemicals and heat. Tanning significantly improves leather’s
ability to flex innumerable times without breaking, to endure repeated wetting
and drying. And since leather is a protein fiber rather than a synthetic,
it appears to resist contamination more than any man made materials. A general
rule to follow is that any chemical disinfectant that’s safe for materials
used in firefighter turnouts will be equally safe for disinfecting leather.
Leather, More Abrasion Resistant
Perhaps the most important attribute of leather as a component of firefighter
turnouts is its superb abrasion resistance, markedly higher than any turnout
material available today for reinforcing material in knees, cuffs, elbows
and shoulders. Leather simply lasts longer, as Taber Abrasion Resistance
below shows.
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ABRASION RESISTANCE
Tested on a Taber Abraser, Model 503 Standard Abrasion Tester
using H-18 Calibrate wheels, 1000 gram load, vacuum level 100
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| MATERIAL |
CYCLES TO BREAK |
| 7.5 oz. Pbi® |
400 - 450 Range |
| 7.5 oz. NOMEX® |
400 - 450 Range |
| 7.5 oz. MILLENIA® |
500 - 600 Range |
| ADVANCE® |
400 - 450 Range |
| ARASHIELD® |
3,000+ |
| LEATHER |
After 10,000 - No Break |
Globe has consistently subjected leather to laboratory tests in its
own lab as well as closely monitoring ongoing testing elsewhere. Additionally,
we have consulted with leather suppliers and independent labs such as
the University of Cincinnati, Department of Basic Science in Tanning
Research, and we will gladly share our findings with you upon your request.
These and other authorities validate our claims on the superiority of
leather as a garment reinforcement for body areas most prone to wear.
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