Bonding yarns and separating yarns: The paradox of low melt yarns

A delicious ice cream. Ice in an ever-diluting glass of cola. An ancient glacier. These are things that we do not want to melt, but there are times when we can take advantage of a material’s ability to melt at a low temperature. Low melt yarns are a special type of yarn normally made from polyester, nylon, or copolyamide with special characteristics that take advantage of a lower-than-normal melting point.

Low melt yarns are often used as bonding yarns in the fabric upper of shoes like these
The upper fabric of shoes like these are often shaped by using low melt yarns as bonding yarns in a thermoforming process

The normal melting point of Nylon is between 220°C and 255°C, and the melting point of polyester is 260°C. Low melt yarns are yarns that are designed to melt at temperatures much lower than this, anywhere between 60°C and 110°C. This gives potential users plenty of flexibility in their manufacturing processes. Low melt yarns can be twisted with other yarns, to allow for an even greater range of characteristics and uses. Low melt yarns are often twisted with normal melting point yarns and filaments like glass. Lowering the melting temperature allows for two broad uses:

Bonding yarn

Low melt yarns can be woven into a fabric which then be heated and moulded into a desired shape in a process called thermoforming. 

Low melt bonding yarns, particularly ones twisted with other normal melting point yarns and filaments like glass, retain much of their original tensile strength, while being held in a defined yet flexible shape. As the bonding temperature is reached – normally 15°C to 30°C higher than the melting point  the low melt yarn becomes adhesive . Low melt bonding yarns are used to make labels and embroideries that can be adhered to other textiles with the simple addition of heat. 

Another common use of these low melt yarns is on the upper of fabric shoes, to fix the shape of the shoe and add some structural integrity without which the upper part of a fabric shoe would have the integrity of a sock. Bonding yarns are available in a large variety of yarn counts and colours.

Separating yarn

Low melt separating yarns can be used in applications where textiles and textile products are produced together and need separating afterwards. By using a low melt separating yarn, you can heat the finished product to the melting point of the yarn in order to separate them cleanly and quickly. Low melt separating yarns are available with melting points, and thus separating temperatures as low as 60°C. We have separating yarns available in multiple colours and with yarn counts between 75 dtex and 167 dtex.

You can read more about SageZander’s low melt yarns here. Whatever your potential use for low melt yarns, SageZander will endeavour to find one that will work for you. 

We are available at sales@sagezander.com and +44 (0)1260 295264.