Learning Goal: Differentiate knit and woven fabrics, calculate fabric weight (GSM), and select durable apparel trims.

 

  • Complete Lesson Content: Fabric represents 50% to 70% of the total manufacturing cost of a garment. Selecting the correct construction and weight ensures the garment performs as intended.Fabric Classifications
    • Knits (Interlocking Loops): Stretchable, breathable, flexible. Common in t-shirts, hoodies, activewear, and underwear. Examples: Single Jersey, Interlock, Rib Knit, French Terry.
    • Wovens (Interlaced Warp & Weft Threads): Structured, durable, minimal stretch. Common in button-down shirts, denim, outerwear, and tailored trousers. Examples: Plain Weave (Poplin), Twill (Denim), Satin.
  • Fabric Weight (GSM)GSM stands for Grams per Square Meter. It measures the density and thickness of fabric.
    • Lightweight (100 – 150 GSM): Summer t-shirts, linings, light blouses.
    • Medium Weight (160 – 220 GSM): Standard t-shirts, dress shirts, lightweight hoodies.
    • Heavyweight (240 – 400+ GSM): Premium heavyweight tees, winter hoodies, heavy fleece, denim.

Fabric Type

Construction

Typical GSM

Ideal Apparel Application

Single Jersey

Knit

160 – 200 GSM

Standard T-Shirts

Cotton Twill

Woven

240 – 320 GSM

Chinos & Cargo Pants

French Terry

Knit

300 – 380 GSM

Midweight Hoodies & Sweatpants

Denim

Woven (Twill)

350 – 450+ GSM

Jeans & Outerwear Jackets
  • Definitions:
    • GSM: Grams per Square Meter; metric unit defining fabric weight.
    • Lab Dip: A small fabric swatch dyed in a laboratory beaker to test and approve color matching under standard light sources (D65).
    • Trims: Secondary functional or decorative components attached to garments (buttons, zippers, care labels, elastic bands, rivets).
  • Step-by-step Explanation:
    • Identify End Use: Select knit for elasticity or woven for structure.
    • Calculate GSM Requirement: Request fabric samples (swatch headers) and test weight with a GSM cutter and scale.
    • Perform Lab Dips: Send Pantone Textile Color Codes (TCX/TPX) to the dye house; approve lab dips under standard light box conditions.
    • Select Functional Trims: Match zipper types (YKK nylon coil vs. metal) and thread tensile strength to fabric weight.
  • Best Practices:
    • Always use Pantone Fashion, Home + Interiors (TCX or TPG) color codes for exact color matching.
    • Specify pre-shrunk fabrics or mandate fabric washing to keep shrinkage under 3–5%.
  • Common Mistakes:
    • Designing a structured tailored jacket using lightweight jersey knit fabric.
    • Approving lab dips under natural daylight instead of standardized store lighting (D65 light box).
  • Real Industry Example: Uniqlo co-develops proprietary synthetic fabrics directly with Toray Industries (Tier 2 mill) to create HeatTech, controlling fiber structure long before factory cutting.
  • Mini Case Study: Scenario: Brand “Aura” releases a heavy winter hoodie. They order 300 GSM fleece. Upon production delivery, the hoodies sag and feel flimsy because the mill used low-twist open-end yarns without elastane. Solution: Aura should have tested fabric burst strength and yarn quality (combed ring-spun cotton) rather than relying solely on GSM numbers.
  • Practical Activity: Cut a 10cm x 10cm square of fabric from an old cotton garment, weigh it on a digital pocket kitchen scale, and multiply by 100 to calculate its GSM.
  • Assignment: Create a Material Selection Sheet for a High-Performance Running Jacket, identifying fabric content, weave/knit, GSM, zipper specification, and reflective trim details.
  • Lesson Summary: Fabric selection relies on understanding construction (knit vs. woven), density (GSM), and performance trims. Rigorous fabric testing prevents costly mass-production defects.
  • Key Takeaways:
    • Knits stretch; wovens hold structure.
    • GSM measures density; higher GSM equals thicker material.
    • Always use Pantone codes and light box approvals for accurate color execution.
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