What are low melt yarns, again?
Low melt yarns are specialised synthetic yarns that are designed to melt at lower-than-normal temperatures. For example, the standard melting temperature for Nylon 6 (PA6) is 223°C, while the melting temperature of a low melt nylon yarn is typically around 85°C, but can go as low as 60°C. Generally, low melt yarns are available in nylon and polyester.
Why do I want to use low melt yarns?
You tell me, but I can tell you what they let you do! There are two broad uses for low melt yarns. First, they are used for bonding, and second, they are used for separating. Bonding yarns are also known as fusible yarns. They are designed to become sticky when they reach their bonding temperature, so they can be used to bond fabrics together. On the other hand, separating yarns are designed to lose strength when heated, meaning sections of fabric can be separated from one another when heat is applied.
Where else could I use low melt yarns?
The applications for bonding and separating yarns are different, but the broad answer is obviously textiles! Bonding yarns have a wide range of uses in the textiles industry; there are some common uses and some more innovative uses that merit consideration. We’ve written before about how they are used to fix the shape of fabric uppers on trainers.
Low melt yarns are commonly used to fix carpet backings and edges. In order to prevent carpets or rugs from unravelling or fraying, the edges are often stitched with a yarn that holds the edge together. Using a bonding yarn to do this can make the edge more durable, by preventing the stitching from unravelling with wear. Tufted backings are often also fixed with a low melt yarn in order to prevent the tufts from coming out of the carpet or rug with time.
Low melt yarns can also be used in applications like composites manufacturing. Low melt yarns can be used to fix woven carbon fibre before it is impregnated with resin. Carbon fibre filament is very smooth, so fibres in the woven fabric can shift and become wavy, which can reduce the strength of the final composite. They can also be used to stitch layers of carbon fibre fabric together to in order to improve shear strength. Standard, non-low melt yarns can affect the final strength of the composite negatively when used in this way.
Are there any disadvantages to using low melt yarns?
Low melt yarns are obviously susceptible to heat. Some wash and dry cycles washing machines and dryers are high enough that they could melt some of the lower-temperature low melt yarns, meaning they have to have been fully heat treated before being sent out to customers. Furthermore, low melt yarns are not well suited to applications where the rest of the product is not able to withstand the temperatures required to activate the low melt yarn. When the rest of the product cannot withstand the temperature required to melt the yarn, water-soluble yarns are a reliable alternative to low melt separation yarns.