From the research results I have examined, it appears that a shrunken
wool item can seldom be restored to its original size/shape (and loose
knits would show more stretching promise than tighter knits). I
imagine that this is not the answer you were seeking but I fear it is
the only correct answer for your question and I ask that you bear with
me and examine the evidence I have found.
Blocking the item (wetting it and stretching it back to its original
size for drying) would seem to be the best way to remedy your problem.
However, having had an episode with a shrunken wool sweater, I recall
that blocking did not help in my case. My sweater never regained its
original size; it remained about four sizes too small. Considering I
hadn't washed the sweater (I had sent it to the dry cleaners and they
had obviously washed it) I was fairly upset with the dry cleaning
establishment and they offered no compensation for their poor
Marilyn Roberts in "Thoughts on Blocking" states at
"It's been my experience that no amount of blocking will save a poorly
knitted or shrunken garment. I[f] you have knit it too small, that's
the way it goes. Every time you wash that garment, it will remember
its former shape and you'll have to re-block it. Wool remembers all!"
The response to a question from "Care of wool blankets and products"
"Unfortunately, the shrinkage that occurs in wool is not
reversible....The outside of wool fibers are covered with overlapping
scales that run in one direction, much like the shingles on a roof.
Wool shrinkage occurs when these scales become interlocked from
exposure to moisture and agitation, such as during the washing
process. Once interlocked, the scales cannot be released due to their
physical structure. Attempts to forcefully stretch shrunken wools can
weaken and damage the fabric."
However, this is also stated there with regard to sweaters:
"A possible exception to the above information is in the case of a
wool sweater. Due to the flexible knit structure of sweaters, you may
be able to gain a little size back by blocking the sweater (if the
shrinkage is not too severe). To block the sweater, gently hand wash
in cool water and squeeze out the water. Roll in one or two towels to
remove additional moisture. Then lay the sweater out to dry. When you
lay out the sweater, try to restore the original shape and size by
stretching and smoothing."
I found other tips for stretching wool sweaters (jacket wools are
usually denser to begin with --like a wool blanket weave-- so keep in
mind that the methods below may not work for your jacket):
"To stretch a shrunken wool sweater, soak it in a tub with a mixture
of hair conditioner and water. Gently pull the sweater to
reshape....Another way to stretch a sweater would be to dissolve one
ounce of sodium borate (borax) in a couple of tablespoons of hot
water, add the mixture to a gallon of lukewarm water, immerse the
garment, and pull gently into shape. Rinse in a gallon of warm water
with two tablespoons vinegar."
Another cream rinse tip at
http://pages.tipking.com/letters/letter_13.shtml seems to support this
possible remedy for a shrunken sweater.
Also see "How to unshrink a wool sweater at
http://www.kottke.org/00/01/like-an-idiot-i-threw that includes the
information "When wool gets wet and warm, the fibers in the wool lock
themselves together and don't want to let go, resulting in shrinkage
(you can get wool warm or wet, but not both)."
Another informative article appears at
http://www.fuzzygalore.biz/articles/wash_sweater.shtml that includes
"When you're dealing with wool, the main pitfall is fulling. So we
recommend you start by reading our article on fulling so you know what
the process is about, and what not to do." Their link to the article
on fulling was a dead link but at
http://www.glmerc.com/sleeping/wool.htm it is explained as
"Pre-shrinking is really a Fulling Process that all wool yarn is
subjected to. Before the fulling process you can actually see through
the 4 ply woven yarn. It is very loose. The fulling process is used to
take woven yarn and make it into usable cloth. The fulling process
uses zero heat. The woven wool is wetted and is rolled along a
stainless steel tube where it is pounded by wooden clappers. This
pounding creates friction (thus its own heat) and after a
predetermined amount of time the woven yarn shrinks up (or as we
learned earlier, the fibers lock upon themselves)."
The above article also offers "...another characteristic of wool
yields the secret of why wool sweaters and clothing knitted from wool
yarn can sometimes shrink. Two conditions are required for wool to
shrink. Water and heat. The outside of the wool fiber is
hydrophobic?hates and repels water. The inside of the wool fiber is
hydrophilic?hollow and absorbs water."
Some outer wool garments (jackets, coats, cloaks) are made from boiled
wool. The definition at
http://www.backpacker.com/jargon/0,2672,469,00.html explains that it
is "Wool fabric that has been washed in hot water and felted to give
it a tighter, more weather-resistant weave; less subject to extreme
shrinking than plain wool weaves." Boiled wool is very warm and
thick, and great for colder climates. More about it may be viewed at
http://www.sew-whats-new.com/boiledwool.shtml - if you are often out
in wet climates in your area, you may want to consider purchasing a
boiled wool jacket as a replacement. Because they are pre-shrunk,
they offer longer service for the wearer.
Should you require clarification of the links or information I have
provided, please request it before rating and closing your question
and I will be happy to respond.
shrunken wool blocking
"stretching a wool jacket"
"stretching a wool sweater"
"wool sweater" stretching
"boiled wool" definition
making "boiled wool"