nfortunately, not all
fibers are suited to making quality roving
or batts. Here are some fiber characteristics
that don't make good roving or batts and possible solutions:
on-uniform
Fiber - The best results are achieved when the individual fibers in
a job are consistent in staple length and diameter. Violation of this simple
precept causes the most processing problems and results in suboptimal quality
of the resulting roving and whatever finished product is made from it. [More...]
The Solution: In the best of all possible worlds, producers sort, or at the least skirt, their fiber
on shearing day so that fiber offered for sale is relatively consistent in length and diameter. Before buying a fleece, consumers should
carefully inspect it to see that it is free of veg, dung tags, and other debris.
Next look at the edges of the fleece. Compare the length of the fiber staple there with the length of the staple in the middle of the
fleece. They should be about the same length.
hort
Staple - A strong roving cannot be made from short stapled
wools. A strong roving remains intact when pulled from the bump;
a weak roving will part. If you compare two rovings of identical diameter
but different staple length, the roving made from shorter staple will be weaker.
This is because of friction, the same physical principle that dictates the
amount of twist you need to make a strong yarn. See the description of slippery
fiber below.
The Solution: You could blend with a
longer staple fiber but that presents its own set of problems later. When
roving contains mismatched staple length fibers, the shorter fiber will sometimes
fall out during spinning or may be the source of pills in the finished product.
Wait a little longer between shearings.
oo
Much Crimp - High amplitude crimp
is not a bad thing. However, crimpy fibers can be thought of as little springs.
As the web stretches from the doffer
to the bump winder, these little
springs can relax into their unstretched state. The fibers will be much more
likely to relax with a short staple. A combination of crimp and short staple
can make quite a nice roving if the crimp isn't too springy because the crimp
increases the friction between individual fibers. Too much crimp though can
make threading the bump winder nigh unto impossible because, while the carder
is stopped for threading, the web between the doffer and the bump winder has
time to relax. If it relaxes too much it will part or the stresses put on
it when we restart the carder will cause it to part.
The Solution: Bend with a longer staple
fiber or with a fiber that has less crimp
oo
Little Crimp - This is generally not too much of a problem. It is a
contributor to the short staple and slippery fiber problems.
lippery
Fiber - Getting strong roving from slippery fibers is like trying to
turn a door knob with wet soapy hands. Slippery fibers are doubly difficult
because not only do they make weak roving but they usually don't make good
batts either. Slippery fibers simply fall off of the storage roll as they
are carried around it. What we end up with is a cloud of fiber on the floor.
We have experienced this problem most with suri alpaca, the so-called "suri"
llama, and mohair.
Fleeces like these have a common characteristic - lovely sheen. Unfortunately,
that sheen is indicative of a reduced number of serrations, or scales, on
the cuticle and these scales are not as prominent. Processing relies on the
"felting" tendency of the fibers. As the mechanical action of the
processing manipulates the fibers the scales interlock. Because these slippery
fibers don't offer as many connection points, the web leaving the doffer often
cannot support its own weight. Microscope photographs of various fiber types
can be seen on the Yocum-McColl
Testing Laboratories web site.
The Solution: Blend with a "coarser"
fiber. This has proved to be an acceptable solution to many of my customers
who have me card their mohair. In these
cases a modicum of sheep wool of an appropriate color is added to the mohair
during a blending pass through the carder. The sheep wool adds just enough
"cling"e; to make an acceptable roving. Sometimes I have extra sheep
wool to add to the mohair but prefer that customers supply their own if possible.
ong
Staple - Very long stapled fibers can wrap around the rollers of the
carder and fill the carding cloth. Once that happens the carder can no longer
card. The rollers on our carder are about 15 inches diameter.
The Solution: Every lock must be cut
so that the staple is less than the diameter of the rollers. Shear your animals
more often.