Silk is some of the smoothest material out there, so it’s very easy to distinguish. Silk thread is very fine, even thinner than cotton or synthetic material. Hemp and jute have a unique brown coloring you can use to help distinguish them. Ramie, made from nettles, is also thick, stiff, and not very pliable. It’s usually mixed with cotton. Animal products like wool are soft, but can make you feel a little itchy. The strands in these types of yarn are different sizes and are not very pliable. Synthetic materials are very difficult to tell apart outside of a lab. It tends to be soft with a consistent thickness. Try burning a sample to determine what kind of synthetic thread you have.
Most animal products, including lower-quality silk, look dull and dark. It absorbs light. Acrylic yarn sparkles from the material inside of it. It looks like it is made up of small grains of sand. Cotton and other plant products are mostly dull. Specialized ones like bamboo and mercerized cotton shine like a reflective mirror.
Animal-based wool smells like animal hair. It usually smells similar to a wet dog or sheep. Cotton, alpaca, and other types of wool always smell a little when wet. Synthetic fibers don’t really have a strong scent, even when wet. You might be able to detect an oily, artificial smell sometimes. Synthetics also can absorb odors from nearby things. Many plant-based yarns, such as cotton, don’t have much of a smell, but burning them can help you identify them.
If you have a microscope available, you have a much better chance of determining exactly what kind of yarn you have. Synthetic yarns, in particular, are difficult to tell apart outside of a lab. In general, animal fibers twist and curl a lot. The exception is some types of alpaca hair that normally grow straight. Plant-based fibers look straight, like they have been pressed with an iron. Cotton and bamboo are a couple of examples. Silk is technically an animal-based fiber, but it also looks straight. Most synthetic fibers also look straight, although they don’t always look as perfect as plant fibers. Acrylic ones tend to be thin and consistently wavy, so they are often easy to distinguish from animal fibers.
Felting is when you fuse pieces of yarn together by hand. It can’t be done with most types of yarn, so it’s useful for recognizing wool and other animal products. Another way to do this is to dampen a strand of yard, roll it into a ball, and see if it sticks together. [6] X Research source
For example, if the yarn is made up of 6 individual fibers, separate them into groups of 3. You only have to fray the ends you plan on sticking together for the test.
Keep the yarn on a flat surface. The pieces will be easier to combine that way. If you try doing it while holding the strands up, they will come apart before you have a chance to finish the test.
You could also dip the yarn into water, but be careful not to pull the threads back apart. It’s easier to wet your fingers and then rub the water into the strands.
Wool is very common in felting, but other material, like angora, alpaca, and llama fur also stick together. Even silk is good for felting. If you’re still unsure about what kind of yarn you have, do some other tests. Burning or bleaching a sample could help you get more information.
If you’re not sure 4 in (10 cm) will be long enough, it’s fine to cut it a little longer.
You can hold the yarn in your fingers, but be extra careful to avoid the flames.
Make sure you’re working over a non-combustible surface. Stay away from anything that could potentially catch fire. You can do the test over any non-combustible surface, but have water nearby just in case. For additional safety, make sure you won’t be disturbed while you’re burning the yarn. Keep pets and children out of the room temporarily.
Light only the end of the yarn. You don’t have to burn the entire sample to finish the burn test.
Cotton burns right away and has a yellow-colored flame. Linen is similar, but it burns more slowly. Hemp and jute burn similarly to cotton, but both have a very bright flame. Silk and other animal threads burn slowly without melting. They all shrink like synthetic yarn does. Silk chars, but animal fibers like wool burn orange. Acrylic yarn and most other synthetics burn at a quick rate and shrink from the heat. Nylon and polyester burn more slowly than acetate and acrylic. Spandex doesn’t shrink.
Cotton, linen, hemp, jute, and rayon are all similar. Cotton and rayon smell like wood, but the others tend to smell more like rope. Silk smells sort of similar to charred meat or burning hair. Wool and other animal fibers always smell like hair or feathers. Acetate smells kind of like paper and vinegar. Acrylic yarn smells strong, unpleasant, and fishy. Nylon and polyester smell much milder than acrylic yarn. Nylon has a slight celery scent, but polyester smells pretty neutral overall.
Cotton yarn looks brown on the end with a fine, feathery gray ash. The yarn won’t look melted. Linen, hemp, and jute will all look similar to cotton, but the ash stays in the shape of the yarn. You won’t see much residue left on burned rayon. It melts slightly, leaving fluffy, black ash. Animal-based yarns don’t melt, but they leave a black bead behind that can be crushed into a gritty, black powder. They also burn out on their own. Synthetic yarn leaves a solid, black bead. Be careful, since it always continues burning for a little while even after you put out the fire. Polyester leaves more of a tan or cream-colored residue, while spandex has a soft, sticky black ash.
Bleach is unlikely to damage a glass, and you can easily wash out the container afterward if you plan on reusing it. Plastic containers are also safe to use in most cases. You could try reusing a jelly jar, for instance. A lidded container is better since you can seal the bleach in. Bleach fumes are very strong and harmful to breathe in, so keep the jar covered.
Color-safe bleach is made with hydrogen peroxide. It’s not as strong as regular bleach, so it could throw off the test. Once you have the bleach out, make sure no one else can mess with it. Keep children and pets away from it for their own safety.
The yarn doesn’t have to stay submerged in order for the test to work. As long as you get bleach all over it in the beginning, the organic material will dissolve.
If you have ever spilled bleach on a shirt, you know how quickly it works. You may start to see results as soon as 5 minutes after starting the test! Keep the jar sealed and stored in a safe place where it won’t be opened or knocked over.
Wool and other animal products fizz not long after you drop them into the bleach. They dissolve within a day. Silk yarn is a little slower to disappear, but it will still dissolve within 2 days. Bleaching is a great way to distinguish blended yarn. If you notice that the yarn bubbles, then partially dissolves, it’s blended. It is usually something like 50% wool or silk and 50% acrylic. The bleach test is great for telling you what kind of yarn you have, but not what specific type. For example, you won’t be able to tell apart wool and alpaca hair without inspecting them on your own.
The acetone in nail polish remover is what dissolves acetate yarn. On other types of yarn, such as those made with color-safe wool, acetone removes stains. Acetone can discolor some types of yarn, so make sure the yarn is actually dissolving instead of changing color.
