The addition of spandex yarn in the textile industry has changed the sector in many ways. While traditional metrics like yarn count (NE) and GSM (grams per square meter) have long dictated fabric quality and feel, the inclusion of spandex is adding a new layer of complexity, impacting not just a fabric's stretch but also its weight, cost, and design possibilities.

Understanding the yarn count and GSM

At its core, fabric quality is defined by two fundamental metrics:

Yarn Count (Ne): This number indicates the fineness of the yarn. A higher count (e.g., 60s, 80s) signifies a finer, more lightweight yarn, ideal for soft, breathable fabrics. Conversely, a lower count (e.g., 20s, 30s) indicates a coarser, heavier yarn used for more durable and structured materials.

Fabric GSM (grams per square meter): This metric measures the fabric's weight and density. It's a crucial indicator of a garment's intended use.

• Lightweight (100–150 GSM): Perfect for summer shirts, linings, and innerwear.

• Medium-weight (150–250 GSM): The standard for everyday T-shirts, dresses, and casual wear.

• Heavy-weight (250+ GSM): Reserved for durable items like hoodies, sweatshirts, and towels.

Adding weight and complexity

Spandex, also known as Lycra or elastane, is a synthetic fiber renowned for its exceptional elasticity. When blended with natural fibers like cotton, it provides stretch and recovery, making garments more comfortable and form-fitting. However, its impact extends beyond just elasticity; it directly influences a fabric's GSM and, consequently, its cost.

How spandex impacts GSM

Contrary to popular belief, adding spandex to a fabric blend, even in small percentages, typically increases the overall GSM. This is because spandex yarn, despite its fine appearance, is denser than most natural fibers like cotton or polyester. When a spandex filament is wrapped by or twisted with a cotton yarn, the combined yarn becomes slightly heavier. This results in a finished fabric that, for the same given yarn count, has a higher GSM than its 100 per cent cotton counterpart. For example, a 30s cotton single jersey might have a GSM of around 150-160, while a 30s cotton/5 per cent spandex blend could easily jump to 170-180 GSM.

The cost equation

The introduction of spandex also adds a layer of complexity to costing. While the primary cost is the spandex fiber itself, there are other factors at play. For example, raw material cost as spandex is a petroleum-based product and is significantly more expensive per kg than cotton or polyester. Even a small percentage can increase the raw material cost of the yarn. Moreover, special machinery and more delicate handling are often required during knitting and weaving to prevent the spandex from breaking or losing its elasticity. This can slow down production and increase operational costs.

Spandex also requires specific dyeing processes and chemical treatments to ensure the color consistency with the blended fibers. These specialized finishes can add to the overall cost. Fabrics with spandex are often marketed as "stretch" or "performance" fabrics, allowing brands to command a higher price point. This allows them to pass on the added costs to consumers who are willing to pay for the comfort and durability benefits.

GSM and cost comparison

The following hypothetical data table illustrates the impact of a simple 5 per cent spandex blend on a common single jersey fabric.

As seen in the table, the 5 per cent spandex blend not only increases the fabric's GSM but also adds a substantial premium, making the fabric approximately 25-30 per cent more expensive at the raw material stage.

The bottom line for designers and consumers

The "spandex effect" is a critical consideration for designers and manufacturers. While it offers a pathway to creating more comfortable and functional apparel, it requires careful planning to balance the desired hand feel and performance with the increased weight and cost. For consumers, the price tag on a spandex-blended garment reflects not just the stretch but also the specialized processes and premium materials that went into its creation. The takeaway is clear: the modern textile landscape is no longer a simple calculation of yarn count and weight; it's an intricate dance of fibers, function, and finance, with spandex leading the way.