How Is Wool Made Machine-Washable?

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).


About sweatyknitter

Fiber art devotee, author, and amateur artisan bread baker.
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27 Responses to How Is Wool Made Machine-Washable?

  1. knotrune says:

    I don’t even have a dryer. Sometimes it’s annoying, as it is a drag getting the indoor hanging things set up and putting all the clothes on them, but there’s nowhere to put a dryer and washer/dryers are supposed to be inefficient. My clothes have always lasted well as I’m not very hard on them, but my husband is always wearing holes in his socks, dryer or no dryer!


  2. Thanks for reading and reblogging … There is more than one trade off, isn’t there, with machine washable wool?!

    Liked by 1 person

  3. Very interesting! I must be like your son: Wore lots of woolens hand knit by my grandmother in Norway and am not bothered by the fibers! (Yes, that Pineapple stacks hat pattern of yours is definitely a keeper!)


  4. Agreed … I also find my clothes last far longer with line-drying (as opposed to machine drying).


  5. Thank you for reading and commenting!


  6. Thanks for your thoughts. I just knit a sweater for the grandson out of non-machine washable wool, but I checked with my daughter first. 🙂


  7. Do you put them in mesh lingerie bags too? I do that to decrease their movement while being washed.


  8. Thank you, and thank you for reading and commenting. It was good to find out why machine washable wool always felt “different.” 🙂


  9. Cheryl says:

    Really edifying! Always a pleasure to read 🙂


  10. fabrickated says:

    Very interesting. My machine washes cold and has specific wool programmes which seem to leave my jumpers intact.


  11. Nicky says:

    Thank you as always for sharing. This is the 4th post in the matter of weeks discussing the processing of machine washable wool. I go back and forth on if I should switch to just using pure natural fibers but like you I end of gritting my teeth and reminding myself that the items are not for me and I have to cater to the giftee’s needs. Interesting subject.


  12. Nicole Tavares says:

    Very interesting and informative – Thank you!


  13. knotrune says:

    I’m baffled as to why anyone would make a yarn washable and then dye it in a non-colourfast way! Surely the whole assumption is that the user is going to wash it? 🙂

    I agree with your comment above that modern society has people washing clothes far too often. It is terrible for the environment and quite unnecessary.


  14. Rebecca says:

    Great post…I have been meaning to write a post on machine washable wool all year…now I don’t have to! This was really interesting. Three points I would to like add though. This kind of processing is energy and resource intensive and adds to the carbon footprint of the yarn. It also changes the feel of the yarn which you allude to. My son has been raised a woolly kid and has never complained about scratchy yarn but he is almost phobic about merino thermals which have been heavily processed. He hates the feel of the fabric when it gets wet, he says it is crunchy and now refuses to touch any processed merino…and him an Australian boy! Finally, the processing changes the way the plies and resulting yarn behave, the fibres can’t mesh together particlarly well. This is fine for small things like tightly knit socks and baby things but a cabled sweater will stretch and hang, the fibres can’t grab each other and give structural support to the garment. Having said all this, of course, I have still knitted with machine washable yarns because it is, well, machine washable, and that can really help when gifting to non knitters. So glad you’ve enjoyed Pineapple-stacks-hat so much!


  15. Reblogged this on Craft Eccentrics and commented:
    Really interesting because so many people would have wondered about the processes that make modern yarns easily washable. Thankyou for the information. 🙂

    Liked by 1 person

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  17. Thank you … my grandmother was formally uneducated woman but such a wise woman in so many ways.


  18. Just what we all need … more to worry about. 🙂


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  20. Fascinating, your posts always open an intriguing can of worms for me, more to reflect on! 🙂


  21. Your posts are always so informative! This was a great read! Thanks!


  22. Hmmm, I don’t think I’ve tried Swish. Isn’t interesting how by the sense of touch alone we get a good sense of what process was actually used to make the wool machine washable?!


  23. What’s the old saying … something along the line of “If it seems to be too good to be true, then it probably isn’t [too good]”? 🙂 I sometimes wonder if people just don’t tend to overwash everything – I mean, wear it for an hour and into the laundry bin it goes!?


  24. I originally intended to knit my first grandchild’s blanket out of cashmere, but my daughter nixed that one! 🙂 They are busy folks, so most of what I knit the grandchildren is machine washable wool … I don’t think it feels as nice as “real” wool but i grit my teeth and tell myself “It’s not for you!” 🙂


  25. Thanks for writing this up! I was just thinking about this, because my Knit Picks Swish DK (superwash wool) feels more like regular wool than a lot of other superwash yarns I’ve found. I guess they probably use that last method!


  26. jenyjenny says:

    This question has always been in the back of my mind. Washable wool seems too good to be true.


  27. Another helpful, informative post. I prefer natural but the young mothers want machine washable. I’ve splurged on lovely wool for my grand-daughter and offered to do the hand washing!


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