Re[2]: MR:REQ:Rapier legal garb

[nachtanz@patriot.net (Susan and Ken Reed)]

Poster: nachtanz@patriot.net (Susan and Ken Reed)

>
>Poster: "Chuck Graves" <chuck_graves@mail.hq.faa.gov>
>
>>...Other materials need fewer layers (heavy cotton duck works with two), or
>>more (you'll get to about 15 layers of silk before you run out of money and
>>still not have acceptable armor).
>
>The latter comment is interesting since silk is considered the hardest
>natural fiber known to man. Out of curiosity, Robert, have you ever performed
>the punch test using a tight-knit silk scarf? I know of a historical
>reference (quite out of period) where a gentleman was killed by a gunshot
>wound. When the surgeon examined the man, he was able to extract the wound
>(to the heart, by the way) by pulling the gentleman's silk scarf back out.
>The bullet was completely surrounded by the silk and the cloth was fully
>intact.

ALERT: More about textiles than you ever wanted to know!

I want to know what you mean by "hardest." The measure of strength for
fibers is called "tenacity," and is a measure of how much load the fiber
can take before it breaks. The tenacity of silk is 2.4 ot 5.1 grams/denier
(denier is a standard measure of length in textiles). In comparison the
tenacity of cotton is 3.0 to 5.0 g/den dry and 3.6 to 6.0 g/den wet (yes,
cotton is stronger when wet!); the tenacity of linen is 5.5 to 6.5
(generally strongest of natural fibers); the tenacity of wool is 1 to 2
g/den. Although individual wool fibers are weak, they have other properties
when spun together to make the yarn and the woven or knitted fabric very
strong.

Tenacity is not the only measure of a fiber or a fabric's strength.
Abrasion resistance is one that would be very important for fencing armor.
The abrasion resistance of silk is rather poor compared to cotton, linen or
wool. Silk fibers have no protective scales or coatings to help it resist
abrasion. Silk also deteriorates readily in sunlight and is very
susceptible to alkaline damage (as is wool).  Linen may also deteriorate in
sunlight after very long exposures and cotton's strength remains high
during sunlight exposure, although it does discolor over time.

Another concern in armor are the measures for fabric durability of various
weaves: tear strength, tensile strength, and abrasion resistance. In
general and other factors being equal, a more tightly woven fabric or a
plain weave fabric has lower tear strength than a loosely woven fabric or a
basket, ribbed, twill, or satin weave. Try ripping a piece of percale, then
try ripping a piece of gauze that has nearly the same thread thickness.
Tighly woven fabrics and plain weave fabrics do have better tensile
strength and abrasion resistance than more loosely woven fabrics or weaves
with longer floats (satins, twills, basket weaves, etc.; a float occurs
when a yarn passes over two or more perpendicular yarns). For armor, I
would be more concerned with tear strength, as any nick or weakness in the
fabric can cause a tear and render the wearer vulnerable.

The problem with anectdotal information is that is presents the unusual and
exceptional as commonplace and does not give the other factors that played
a part in the result.

Being pontifical and a stuffy purist again,

Teleri Talgellawg
(Speaking for Susan Reed who has a M.S. in Textiles)
nachtanz@patriot.net


******
Susan and Ken Reed                 AFPOPA               nachtanz@patriot.net


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