Winter and Hypoallergenic Yarns

The first snow came today.

It’s beautiful. Big, wet, fat fluffy flakes of the best sort – the sort which promise to melt off of the roads in a couple of hours. Flakes litter the lawn, which is still a sharp green and provides a vibrant counterpoint to November gray. The whole image combined with the Bach concerto playing in the background is perfect. A gentle, fleeting introduction to winter and official sweater season.

Wool sweaters seem to be traditional for winter and snow. Heavy, bulky, sweaters which manage to survive years of use. I have inherited several wool pull overs, each I treasure as much for their warmth as for the giver.

I’m fortunate. I don’t have a wool allergy, something for which I am incredibly thankful. But I knit for people who do, so I did a little research and came up with some helpful information.

INTRODUCING: The Incredibly Brief Guide to Hypoallergenic Yarn

An internet search for hypoallergenic yarns gives limited results. This isn’t your search engine’s fault. It’s in the definition of hypoallergenic, meaning “Less likely to cause allergic reaction” not “allergen free.” Amazingly, not a single country has yet to establish criteria for a hypoallergenic certification, which means that there are no guarantees for any hypoallergenic claims – not in yarn, jewelry, clothing, etc. So you can’t hold it against me, or the yarn company, if something should be hypoallergenic and still causes an allergic reaction.

Obviously, some yarn actually is more allergy friendly than others. If we are going to avoid all the fabulous synthetics now available on the market and focus solely on natural fibers, we can break down the hypoallergenic fibers into two categories:

Category 1: Plant Based Fibers

The most obvious option is cotton. Knitters love cotton. Cool for summer knits, non-stretchy for lace work, doesn’t pill easily, and can (if one is careful) be machine washed.

There’s also linen and hemp.

I’m more interested in bamboo.

Part 1 – How it’s made (Including a brief appearance by Schweizer’s Reagent)

All bamboo yarn is actually viscose rayon, which isn’t what I expected. The first time I held bamboo yarn, I pictured a process involving skinny bamboo trees being somehow split into bamboo fibers which were then spun into yarn. Not so. Not so at all.

Making bamboo yarn starts out as agriculture—growing the plant—then switches over to chemistry (I’ve included a video) before finally rejoining the realm where knitters and spinners feel comfortable—yarn manufacture.

Here’s my explanation of how it works. You can also read a more detailed explanation of the sixteen step process here on Wikipedia.

First, Cellulose fiber is extracted from the leaves and pith of the bamboo plant. This is then dissolved with some potent chemicals until all the ‘plant’ stuff is gone and all that remains are the rayon filaments floating in the mixture. See the video below for someone who actually did this at home:

Now, the video above actually shows an outdated form of industrial manufacture for rayon using Schweizer’s Reagent – a caustic mixture of copper and ammonia. This method is no longer used in the United States due to the harmful environmental effects.

Actually, the environment and rayon have a history. But that comes later in the post.

According to Wikipedia, then you squeeze the mixture until the chemicals are gone, break up the rayon fibers so they aren’t in a big mat, and let the fibers thoroughly dry out and age. (In the video, they just filter the solution with a coffee filter, and don’t get into all the pressing out liquid and aging processes.)

Rayon fibers at this stage are fairly brittle. So what follows in the manufacturing process adds strength and flexibility to them. A whole bunch more chemicals are added, and the rayon is allowed to age further. Bubbles are removed.

Then the yarn part happens. Fibers are stretched, washed, cut, and spun. The whole thing goes through the yarn process and lands on the shelf of your local yarn store.

So. To be perfectly honest bamboo yarn is not a natural fiber. It is very much a synthetic.

Part 2 – Living with Bamboo (Viscose Rayon) Yarn

Interestingly enough, an internet search for bamboo yarns produced bamboo-cotton blends by Lion Brand Yarn and Classic Elite Yarns which are 52% cotton/48% rayon, and bamboo-acrylic blends from Bernat (86% bamboo, 12% acrylic, 2% polyester) and Caron (25% bamboo, 75% acrylic). This is an attempt to overcome some natural flaws of bamboo fiber, including fibers which split and break easily, a tendency to retain moisture (one common to all cellulose based fibers), and the need for hand washing and line drying garments made from bamboo yarn. 100% bamboo yarns are available, but they are extremely delicate and should be handled accordingly.

Bamboo yarns often claim to be antibacterial. While it is true that the actual bamboo plant has antibacterial properties, the manufacture and refinement process removes this from the finished viscose rayon fiber. In order for the yarn to truly be antibacterial, an additional agent must be added to the finished yarn post-refinement process. Also, untreated bamboo fabrics block UV rays very poorly compared to other fabrics, so a UV block/absorbing agent may also be added to the fiber post refinement process to protect the skin.

Of the bamboo yarns mentioned so far in this article, only Classic Elite Yarns advertised natural antibacterial properties. None of the yarns specified whether they were treated with agents to increase UV protection and antimicrobial properties.

Rayon Viscose sourced from Bamboo struggles to be environmentally friendly. Excessive bamboo harvesting in China is leading to environmental problems (see here and here for two easy examples). The caustic chemicals used, as well as the amounts of water and electricity used during manufacture have also caused concern.

In 2009, the Federal Trade Commission charged several fiber/clothing companies regarding false claims made regarding bamboo, including claims regarding antimicrobial properties and environmentally friendly manufacture processes. To read the complete release click here. No yarn companies were charged.

Category 2: Suri Alpaca Wool

The most common reasons for allergic reactions to wool are fairly simple.

The first and largest reason for a reaction to wool is that wool fibers are irritants. The shape and roughness at a microscopic level causes small scratches on sensitive skin, leading to small bumps, redness and swelling: your classic allergic reaction. However, rather than a classic chemical reaction causing the reaction, the cause is the actual physical injury caused by scratchy wool. Strictly speaking then, people who struggle with this have a wool sensitivity, not a wool allergy.

The solution then becomes fairly simple – don’t use scratchy wool. Use smooth wool, which actually does exist.

A second common reason for allergic reactions to wool is lanolin oil. Lanolin oil, also known as wool alcohols, is naturally present in wool and keeps the sheep dry while living out doors—like a built in raincoat. Lanolin is also extracted from wool and used as a moisturizer in lotions, cosmetics, and occasionally pharmaceuticals. If someone is allergic to the lanolin in wool, then they will probably be allergic to any lotions with lanolin as well.

Solution – Use wool without lanolin.

Alpaca fibers in general are lanolin free, giving it a hypoallergenic status. However, of the two alpaca breeds, Suri and Huacaya, fibers from Suri alpaca have the smaller diameter–ranging from 10-15 micrometers.

To provide a little context, a micrometer is equal to one-millionth (1/1,000,000 or 0.000001) of a meter, 0.000039 inches, or 0.000099 centimeters. The smallest a human eye can see is 50 micrometers, about the size of a speck of dust. The width of a human hair is 80 micrometers.

So Suri alpaca fibers really blow all other wool fibers out of the water. Even cashmere struggles to compete with a diameter of 15-19 micrometers. The thinness and length of Suri fibers allow for very soft yarns, yielding garments that are comfortable for wear close to the skin.

There’s a rule of thumb here for all yarns: The thinner and longer the fiber the softer and less irritating the yarn. The thinner the fiber is, the smoother it is. The longer the fiber is, the fewer fiber ends there are to scratch skin.

The other kind of alpaca, Huacaya, has significantly thicker fibers. In fact, with an average diameter of 27.7 micrometers, they are above the wool industry standard of 25 micrometers for fine yarn. The coarser fibers mean that, even though there is no lanolin, knits from Huacaya may still cause skin irritation.

I think this is what leads to confusion about whether or not alpaca is hypoallergenic. Because it is generally lanolin free, alpaca lacks the allergen which would cause an allergic reaction to wool. However, if one is knitting with coarse, scratchy fibers, the resulting rash will still lead to the impression of an allergic reaction.

Left-over questions and some resources:

There are plenty of hypoallergenic yarns available these days, especially when you take synthetics into account. I only researched two sources for this post, and the amount of information once I started digging was overwhelming.

The one thing I want to point out is that, given the diverse sources for yarn materials today, just because something isn’t wool doesn’t mean that it won’t cause a reaction. Silk allergies exist, so what about silk yarns? If someone is allergic to soy, does that mean it is unsafe for them to wear soy yarn? What about people allergic to grass wearing hemp and linen? I really don’t know the answer to those questions, but I think they are worth asking, especially if the sweater in mind is a gift.

Some Links (In no particular order):

Happy Knitting!

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