From: cosell@world.std.com (Bernie Cosell)
Subject: Re: Scratcy wool (was: Knitted Acrylic Baby Afghan)
Organization: Fantasy Farm, Pearisburg, VA
X-Newsreader: TIN [version 1.1 PL8]
Date: Mon, 25 Jan 1993 09:12:04 GMT

Judith S. Janette (judi@laplace.csb.yale.edu) wrote:

} Just a nota about wool and the "scratch factor"...

} Different types of wool have different "scratch indexes" (for lack of a  
} better pseudo-scientific term). That's because different kinds of sheep  
} have different lengths and textures of wool. From short-haired,  
} coarse-coated Icelandic sheep comes scratchy, warm, water-resistant yarn.  
} Merino yarn on the other hand, is made from longer and silkier-haired  
} sheep. Kid mohair, again, is made from a long and soft-haired beast. 

This is not quite correct.  By any normal standards, few people
would call Merino fleece 'longer' than other breeds' wool --- it is
one of the *shortest* fleeced breeds.  Finest, too, of course, but
short for sure, and that's especially true if you're talking about
comparisons of commercial yarns [which are, by and large, made from
Romney, which is quite a long stapled breed].  But you're onto the
right idea when you point out that it is 'longer' that has
something to do with it, but it isn't the actual staple length of
the fibers that is what is the problem, is the the broken bits: The
difference is not at the macro level [whether the staples are 4" or
12" long], but at the micro level...

As a rule, most commercial scouring facilities use various VERY
harsh solvents to clean the junk out of the wool, and that has the
effect of weakening the fibers and breaking lots of them.  When the
fibers are spun up, there are lots of little ends 'sticking out' of
the spun yarn, and it is these little 'hairs' sticking out of the
yarn that makes it feel scratchy.

Carefully processed and spun, just about ANY breed of sheep's
fleece will produce a nice, non-scratchy yarn[*].  Conversely,
improper [or overly aggressive] processing can make _any_ fleece
produce a scratchy yarn.  This is one reason why folk who are _sure_
that they're "allergic" to wool often discover, to their surprise, that
they are magically _not_ allergic to handspun yarn --- the kind of
handling and care most spinners give their yarn virtually guarantees
a scratch-free yarn.
   [*] We are Merino snobs [partly because that's what we raise..:-)]
   but we got a *suffolk* fleece from a neighbor and Lynn scoured it
   and spun it up to see what it was like, and she was _astounded_ at
   what nice yarn it produced... it was a bit humbling, since you can
   get Suffolk by the ton at about 40 cents a pound.  sigh...

Another criterion is whether the yarn was woolen spun or worsted
spun.  In woolen spun yarn, the fibers are only 'mostly' parallel
[the actual situation is that the staples have just been opened up
enough so that the fibers will draft when spun --- actually
"aligning" the fibers is _not_ a goal of carding!] and so there is a
lot of 'bundling' of fibers in the yarn.  This means that you get a
puffy yarn and one that traps a lot of air [and so makes nice and
warm outergarments], but it also means that the ends of each
separate fiber are sort-of sticking out.

By contrast, in producing worsted yarn, the fibers go through two
additional steps [after carding] before spinning: combing and pin
drafting.  The comber gets all of the foreign matter, short ends
and all of the other fiber-imperfections out.  The pin drafter
actually makes the fibers parallel, so that the ends of each
separate fiber are lying _along_ the length of the bundle [called
"top"] and nothing is sticking out.  Then, when you spin it, the
ends stay 'wrapped up' in the yarn and you get a VERY VERY smooth
and scratch-free yarn --- not very warm [by comparison with woolen
yarn] but a lot nicer feel on the skin.

/Bernie\
-- 
Bernie Cosell                               cosell@world.std.com
Fantasy Farm Fibers, Pearisburg, VA         (703) 921-2358
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