Yarn Structure
The concentration of surface fibers that wind transversely around the untwisted core of a spun yarn determines the cohesion and abrasion resistance of the yarn. A high wrapper fiber density is a defining feature of rotor and air-jet spun yarns, providing the necessary strength to withstand the high tensions of weaving. These outer fibers hold the parallel core bundles together, preventing them from sliding apart under stress.
Spinners record this structural configuration on the spinning machine’s technical datasheet.
Spinning Adjustment
Control of the air-jet nozzle pressure and the draft ratio allows the spinner to manipulate the amount of surface wrapping during production. To achieve the desired wrapper fiber density, the spinning technician adjusts the air pressure in the nozzle, logging the parameters on the machine setup docket. If the wrapping is too sparse, the yarn will exhibit poor cohesion and shed excessive fiber during subsequent processing steps.
Conversely, excessive wrapping can make the linen yarn too stiff, which negatively affects the hand feel of the finished fabric.
Fabric Acceptance
Fabric softness and dye absorption are influenced by how tightly the yarn core is bound by these surface fibers. While a lower wrapper fiber density produces a softer yarn with better dye uptake, the buyer’s quality criteria require a minimum density to prevent yarn splitting during loom processing. This trade-off must be managed during the spinning process, with samples tested in the laboratory and recorded on the yarn shipment certificate before delivery.
If the yarn does not meet the specified wrapper density, the buyer may reject the entire shipment due to the risk of excessive fabric hairiness.
