If we’re going to make beautiful creations out of yarn, it is important that the yarn we use is of good quality. But, what are the different ways to check yarn quality? What is yarn testing methods, and how is yarn strength measured?
Yarn quality is how well it is made. A yarn can have good weight, density and texture. It may even be washable. But, if it is poorly made, the entire knitting project is ruined.
Yarns are used as raw materials for weaving and knitting. Usually, there is no absolute good or bad yarn. There are, however, quality tests that can help determine which yarn is best for your use. TESTEX Textile Testing Equipment is one reliable option for testing yarn quality.
Yarn is made out of either animal-based, plant-based, or synthetic fibers. The animal-based fibers come from sheep’s wool, mohair, or angora. The synthetic fibers come from polyester, nylon, or rayon. The plant-based fibers come from cotton, hemp, or silk. The fibers are interlocked and called plies that are spun into thick strands. These strands range from 1 ply lace to 14 ply super bulky.
Yarn that is of bad quality includes yarn that:
- Breaks in the plies
- Bleeds color
- Prone to piling
There are a few characteristics of yarn to test that include:
- linear density
Testing should be done on a sampling of the yarn in temperatures of about 20 degrees C and 65% Rh to maintain a temperature of about 27 degrees C.
The Twist Test
The twist is the spiral disposition of the yarn that keeps the fibers together. Twist is expressed by the number of turns per unit length, such as how many turns per meter. To determine yarn twist in a single or a plied yarn, a twist tester machine is used to determine the coefficient of twist. This measurement is the level of twist of the yarn. The results are displayed as TPM.
How is yarn strength measured? ASTM D1907 is a denier test by the skein method. 1 Denier is the same as 1 gram with 9,000 meters of material. To give you an idea of strength, a human hair is approximately 20 Denier. Yarn is tested on a machine that spins one meter length and then weighs is to get a strength measurement. The larger the size, the heavier the yarn.
Breaking strength is classified into two methods:
- single end strength testing
- skein strength or Lea strength
Two types of strengths are determined:
- Tensile – the load applied gradually
- Ballistic – load applied under rapid impact conditions
Yarn strength and elongation are tested through Tensile testing equipment that has unique grips to hold the yarn. ISO and ASTM Standard Tensile test method test the breaking strength, elongation, tenacity, and toughness of yarn.
The fineness of yarn is expressed by count, or linear density. In the Metric count, Nm, it is determined by the number of one kilometer yarn weighing in One Kilogram. The Tex or Denier system takes the weight in grams of either 1 or 9 kilometers of yarn.
Yarn evenness is a measure of the level of variation in yarn diameter along its length. It refers to the variation in yarn linear density or mass per unit length of yarn. There are two methods for testing evenness that include using an Uster evenness tester in the capacitive method or a Zweigle G580 in an optical method.
The capacitive method uses a high-frequency generator with electrodes and an open capacitor. The optical method uses a light source and optics.
Out of all of the tests that are done commercially or using testing equipment, there is one that can be done at home. What is yarn testing methods to use to determine whether the yarn is made of wool, cotton, or acrylic? Carefully catch a small piece of it on fire.
The results will be the tell tale sign. If the flame slowly goes out and smells like burned hair, it is probably wool. When you rub the burnt ends in your fingers, it turns to ash.
When cotton is burned, the flame catches quickly and continues burning with a light yellow flame. It will smell like burnt paper. The ash does not fall apart quickly when rubbed between fingers.
If it is made of acrylic, the yarn will catch on fire fast and keep burning for longer than the cotton yarn. The smoke will be black because it is not an organic material with a strong chemical smell. It wlil leave no ash but rather some other black substance that looks like black beads. When you rub them, it is crispy but feels more like plastic.
Before you start your next knitting or crochet project, make sure to look at the label for yarn quality testing information. Of course, you can also get a good idea whether the yarn is suitable by trial and error in using it to test it out.