In the earlier half of the last millennium, those accused of crimes could prove their innocence through a trial of fire or water. Thus subjecting a person to either water or fire, usually represented in the form of hot metal rods or ploughshares (as the peasants would probably have more of these at their disposal), was a way to separate the guilty from the innocent.
Well, we can also use trial by fire and water to separate the wools from the cottons from the acrylics. Generally, most animal fibers will follow wool’s example, and most plant-based fibers will follow cotton’s example. Of course, it is always better to retain the ball band (the paper wrapped around the yarn to label it with the company, brand, fiber content, recommended needle size and washing instructions) to remember the fiber content of a particular skein, ball, or cake of yarn. However, who hasn’t pranced home from the yarn store, ripped off the ball band with fevered abandon, and wound their skein, telling themselves “I’m going to start something with this yarn right now!” only to have to abandon your newly wound skein to make dinner or walk the dog or fall into the internet hole? Then you return to your beautiful new yarn a week later only to discover you can’t find the ball band (psst! look under the couch cushions). Or maybe Great Auntie Mabel sent you some yarn she picked up at a church rummage sale, summing up the note with a, “I thought you would like this. See? You don’t have to spend all your money at that fancy yarn store!” Or maybe, you are a thrifty knitter who searches the Good Wills and second hand shops for old sweaters to unravel and knit anew. The point is, you will eventually end up with yarn whose fiber contents are entirely unknown to you. Time to separate the guilty from the innocent.
One of the really cool things about wool is that it is fire-retardant. What does that mean? Does that mean you should burst into a burning building wearing your brand new sweater and your nifty new woolen leggings to save that copy of Nancy Bush’s book Knitting Vintage Socks you left on your desk? NO! Wool will burn, but it won’t catch fire as quickly as cotton or linen. This is why you should knit that pot holder out of 100% wool, and not use a spare strand of wool as a candle wick.
On the flip side, cotton is very flammable. The white wicks in store-bought candles are made of cotton for this reason. Have you ever used one of the candles with a wooden wick, and it seemed difficult to light? That’s because cotton will catch fire much faster than wood. Think about it. The smaller in diameter the piece of wood or any plant, the quicker it catches fire. This is why you need kindling, like sticks and dry leaves, to start a fire. Those small bits will catch first and burn longer than your match can to light the logs on fire. Cotton is also a plant. The tiny fibers are harvested in a clump from the plant, like little white puffs. Cottage at the Crossroads has a pretty and informative article about the growth and harvest of cotton. If those little sticks can burn quickly, think how quickly those tiny fibers can burn! Point is, don’t use cotton for anything that’s going to be near an open flame or heat source, unless you want that cotton to burn.
Acrylic yarn is the most unique in the trial by fire. It doesn’t burn like cotton or resist flames like wool. It melts. That’s right, acrylic yarn, being made of synthetic (plastic) fibers will melt when exposed to fire and high heat. This is why fire spinners only wear all natural clothes when practicing their craft. It’s better to wear a fabric that will burn and can be put out quickly than a one that will melt onto your skin.
If you try any of this at home, please use extreme caution. Cut a small length of yarn about six inches or less to experiment with. Have water and a fireproof dish at the ready to drop the yarn into if necessary. Please practice good fire safety measures.
Not only is wool fire-retardant, but it is water resistant. When you place a piece of fabric knitted from wool under running water or try to submerge it into a bowl of water, the water will not immediately soak into the fibers, and in most cases will bead up and run off the wool. I highly recommend you try this at home, it’s just so cool to watch. It takes a lot of submerging and squeezing of the fabric to make wool soaked and dripping wet. For this reason, wool is a good option for outerwear in rainy or snowy climates. However, in a torrential rain, I still recommend a good rain coat, pair of wellies, and an umbrella. Be advised: the side affect of submerging your wool in water, is that if there is any heat and agitation, your wool will felt! (Unless it is superwash, but we won’t go into that). Felting occurs when you combine wool with water, heat, and friction. Felting causes the fibers in the wool to interlock together permanently. This can be a really great technique for creating dense, non-stretchy, water-resistant, fire-retardant, incredibly warm fabric. All of which is exactly what you want when you make a tea cozy, or a bag (there will be no spaces between the stitches, and in fact, your stitch definition will disappear) or a hat to go to Antarctica or the northern half of the northern hemisphere.
Cotton loves water, and it will soak up all the water it comes into contact to until it has reached max absorbency. This is why it makes a great summertime fiber, as it is ideal for those sweaty hot months. Cotton also makes a great fiber for knitted wash cloths and dish cloths and towels.
Acrylic, like wool, does not absorb water readily. Cheaper acrylic is more likely to squeak when rubbed with your fingers. Acrylic, unlike wool, will not felt in water, and is much harder to block. The only way I have heard of to successfully block an acrylic item is through steam. Pin the the item out the way you want it, and cover it with towel. Then use the steam setting on your iron to set the new, stretched out, shape. Traditional wet-blocking will not work.