From: haslock@rust.zso.dec.com (Nigel Haslock)
Newsgroups: rec.org.sca
Subject: Re: ancient kilt; fabric width; weaving terminology
Date: 26 Aug 92 22:24:59 GMT
Organization: Digital Equipment Corporation - DECwest Engineering

I got a lot out of a book that I found in my local library called something 
like "A History of Looms". I cannot remember the authors name.

Briefly, a loom is a device for stretching warp threads so that they can be
woven. The easy way is to tie the treads to two sticks, attatch one to a tree
and the other to a strap going around the weavers back (a back strap loom).
This system allows a weaver to produce cloth about 20" wide (there are
exceptions, RARE exceptions). The egyptians tried staking the sticks to the
ground with great success and this technique is still used by desert nomads
for making rugs. Do not try this in a wet climate though. The egyptians also
tried making vertical versions of the staked loom and developed techniques for
lashing the top stick so that it could be lat down as work progressed (trying
to weave above the hight of ones head is unlikely to produce good results).

The egyptians wove mostly in linen. The greeks wove mostly wool and had to deal
with inclement weather. They either developed or adopted the warp weighted
loom. In this type of loom the warp is tied to a stick supported at about
head level. The dangling ends of the warp threads are tied to weights, just
above ground level. One weight is used for a whole bunch of threads for a
number of good reasons. Cloth is woven from the top down and can be as wide 
as the top stick is long. Winding the woven cloth onto the top stick allows
the weaver to make cloth of arbitrary length.

Sometime in the 12th century, the horizontal loom was introduced to western
europe. In this the warp is wound onto the stick (or beam) at the back of the
loom with the ends being attatch to the other stick (or beam) at the front of
the loom. As cloth is woven, it is rolled onto the front beam while more 
warp is unrolled from the back beam. In the middle of the loom is a set of
arrangements for lifting warp threads so that the shuttle can pass underneath
them. The mechanism for lifting a set of threads is called a harness. The
space it creates, through which the shuttle is passed, is called the shed.
A harness is also, sometimes, called a shaft. The simplest horizontal loom has
two harnesses. The most common horizontal looms have four harnesses. Looms
used to make complex patterns used to have draw plates but modern, 17th
century and later, looms simply have more harnesses. One reason that they are
called harnesses is because they ar connected to levers or foot pedals.

Warp weighted looms invariably have a 'shed stick at about waist level. Warp
threads fall alternately in front of and behind the shed stick. To pull the
threads that fall behind the shed stick to a position in front of the other
threads, they are tied to a stick or shaft that lies across the front of the 
loom. Thus the shed stick equates to one harness and the shaft to the second
harness. The uprights of the loom include supports for the shaft to be
held far enough in front to open a shed.

Tabby is a weave structure. It is the simplest weave structure, in which the
weft (the thread that came off the shuttle) passes over one warp thread and
under the next as it travels the width of the fabric. On the return path it
goes over the threads it went under on the previous path and under the threads
it went over.

Twill is a class of weave structures. Denim is a fine cotton twill. A weaver
would call it 2/2 twill because the weft goes over two and under two warp
threads on each pass. The 2/2 pattern moves across the fabric in a constant
direction, one warp thread for each pass of the shuttle. This weave can be
identified by the diagonal lines on the fabric. This weave requires four
harnesses on a horizontal loom.

A weaver quickly learns that twill means almost any weave structure that is not
tabby and can be made with four harnesses. By making the pattern reverse
regularly the lines change from \\\\\\\\\\\\  to \\//\\//\\//\\//\\
                                \\\\\\\\\\\\     \\//\\//\\//\\//\\
                                \\\\\\\\\\\\     \\//\\//\\//\\//\\
                                \\\\\\\\\\\\     \\//\\//\\//\\//\\
                                 'twill'         'herringbone twill'

or even //\\//\\//\\//\\ 'birds eye or diamond twill'
        \\//\\//\\//\\//
        //\\//\\//\\//\\

Unfortunately, the mechanics of a warp weighted loom get in the way of
producing a true diamond twill. Instead the pattern glitches every four
rows to produce a 'broken diamond.' The horizontal loom took an extra 5 or
6 hundred years to reach Iceland and so Iceland used the warp weighted loom
to produce large quantities of revenue earning cloth, all made in this
distinctive broken diamond twill.

The prime purpose of weaving twill instead of tabby is that the threads pack
closer together so that the resulting fabric is both thicker and most wind
resistant than tabby made from the same threads. 

	Regards

		Fiacha
From: Tim@f4229.n124.z1.fidonet.org (Tim)
Sender: FredGate@ocitor.fidonet