Any wool (or protein fiber) is washable by hand and, often, in gentle cycles in cool water. Machine washable wool – wool that can be made into garments that can be tossed into a washing machine with no worry of shrinking – is readily available. Yet for years I have been reluctant to knit with machine washable wool; the wool always felt “different” to me, though I would be hard pressed to explain to someone exactly what “different” means. (Pic source)
In Fibre Facts (1981), Bette Hochberg sheds light on why machine washable wool has always felt “different” to me:
This wool is sometimes treated with chemicals to destroy the scales on its surface. This can decrease strength and durability, and impart a harsh texture to the wool. A less damaging method is to coat the wool with a resin which forms a thin plastic skin over each fibre. This film of plastic masks the surface scales, so they can no longer interlock.
Ms. Hochberg warns, however, that machine washable wool
will not behave like natural wool. When each fibre is sealed in plastic, so are some of its desirable properties. The finest qualities of wool are not used in such yarns.
Bette Hochberg wrote Fibre Facts in the ’80s, so I wondered how technology has changed in making wool machine washable. According to e-How:
Today, manufacturers bleach wool fiber to remove its outer layer and then add enzymes that eat the scales. The resulting yarn has a more lustrous appearance than untreated wool. These alterations also affect how the fiber takes dye, so make sure that any washable wool is colorfast.
Australia’s Michell uses:
KROY ‘Deep Emersion’ technology which is recognised globally as the best method for producing machine washable wool fibre. This method involves the continual immersion of wool sliver in a shrink-proofing solution, resulting in a fibre that holds supreme longevity and durability over synthetic materials, whilst retaining its shape and integrity. …
Another way to make wool fiber machine-washable is to blend it with other fibers that do not have scales. Yarn companies often add plant fibers like linen and cotton to keep the wool from shrinking. Man-made fibers like nylon, polyester and acrylic are also blended with wool to make it machine-washable.
The extra steps to process wool to machine washable wool explains the (generally) higher cost per skein than non-machine washable wool.
Over the last 10 years, I have knit five times with machine washable wool. I used Baby Ull (wool) from Dale of Norway to make blankets for my then-unborn grandchildren (so that was several years ago); a sweater out of Di.Ve’s “Zenith” (for the grandson); and a poncho and a sweater out of Dale’s “Falk” (for the granddaughter). Okay, to be honest, I had a few more projects from machine washable wool: I knit several Pineapple Stacks hats (pattern by Rebecca Marsh) from the yarn remaining from those projects! (That pattern’s been a joy to knit!)
When I gift garments from machine washable wool, I always include instructions on washing, particularly noting that though machine washable, they should never be dried in a dryer!
Here is a useful chart of laundering symbols – many of which we see on yarn labels. (Source) If you’re really bored, you could always pop over to the Federal Trade Commission website and read up on the “Care Labeling of Textile Wearing Apparel & Certain Piece Goods” (16 CFR Part 243).