Understanding Denim Weights and Weaves

When shopping for denim shorts, you'll encounter terms like "lightweight," "midweight," "selvage," and "twill weave." These aren't just marketing jargon—they describe fundamental characteristics that affect how the denim looks, feels, and performs over time. Understanding these concepts empowers you to make informed purchasing decisions and find denim that genuinely suits your needs.

This guide explores the technical side of denim fabric, explaining weights, weave structures, and production methods in accessible terms. By the end, you'll have the knowledge to evaluate denim quality and understand why certain pairs cost more than others.

Denim Weight Explained

Denim weight is measured in ounces per square yard (oz/sq yd), indicating how heavy the fabric is. This measurement directly impacts comfort, durability, and how the denim ages. Weights typically range from around 5 oz for ultra-light denim to 20+ oz for heavyweight specialty fabrics.

Lightweight Denim (5-9 oz)

Lightweight denim is soft, breathable, and comfortable from the first wear. It drapes nicely and moves easily with the body. For Australian summers, lightweight options between 7-9 oz offer the best combination of comfort and structure. The trade-off is reduced durability—lightweight denim wears out faster and may feel less substantial.

Midweight Denim (10-13 oz)

Midweight denim represents the classic sweet spot, offering good structure and durability while remaining comfortable. Most mainstream denim shorts fall into this category. The 11-12 oz range is particularly versatile, suitable for most Australian conditions except the hottest summer days.

Heavyweight Denim (14+ oz)

Heavyweight denim is the choice of serious denim enthusiasts. These fabrics are rigid when new and require a significant break-in period—sometimes months of regular wear before they soften and conform to the body. The reward is exceptional durability and dramatic fade development that tells the story of your wear over years. However, for shorts in warm climates, heavyweight denim can be uncomfortably hot.

The Twill Weave Structure

What makes denim denim—as opposed to other cotton fabrics—is primarily its weave structure. Denim uses a twill weave, creating a distinctive diagonal ribbing pattern visible on the fabric surface. This pattern results from passing the weft (horizontal) threads over one warp (vertical) thread, then under two or more warp threads.

The twill structure gives denim its durability and characteristic drape. Unlike plain weave fabrics, twill weaves create fewer intersections between threads, allowing them to pack more tightly and resist wear. The diagonal pattern also helps denim resist creasing and recover from wrinkles.

Right-Hand vs. Left-Hand Twill

The direction of the diagonal lines distinguishes right-hand twill (RHT) from left-hand twill (LHT). Right-hand twill rises from lower left to upper right, while left-hand twill goes the opposite direction. Most classic American denim uses right-hand twill, which tends to be slightly stiffer with more defined fading. Left-hand twill, famously used by some brands, produces softer fabric that fades more evenly.

Broken Twill

Broken twill alternates the direction of the diagonal pattern, creating a zigzag effect. This weave prevents the leg twist that sometimes occurs with regular twill as denim ages. Some wearers prefer broken twill for its unique texture and reduced twisting, while others favour traditional twill for its classic appearance.

Selvedge vs. Non-Selvedge

Selvedge (or selvage) refers to the self-finished edge of fabric, produced on traditional shuttle looms. The term comes from "self-edge"—the fabric edge doesn't fray because it's finished as part of the weaving process, often with a coloured thread (typically red) marking the edge.

Why Selvedge Commands Premium Prices

Shuttle looms produce narrower fabric widths (typically 28-32 inches) compared to modern projectile looms (60+ inches). This means less fabric per weaving cycle and higher production costs. Additionally, shuttle looms weave more slowly and require more skilled operation. The resulting fabric often has more character and variation than mass-produced alternatives.

Does Selvedge Equal Better Quality?

Not necessarily. Selvedge indicates a particular production method, but quality depends on the cotton, dying, and finishing processes too. You can find exceptional non-selvedge denim and mediocre selvedge denim. However, brands that invest in selvedge production typically pay attention to other quality factors as well, making selvedge a reasonable (if imperfect) quality indicator.

For denim shorts, selvedge is less visible than in jeans (where it shows when you cuff the hem), making it more about fabric quality than visible distinction.

Cotton and Composition

Denim quality starts with cotton quality. The length of cotton fibres (staple length), their strength, and uniformity all affect the final fabric. Premium denim often uses long-staple cotton varieties like Supima (American Pima), Egyptian cotton, or Zimbabwe cotton, which produce smoother, stronger yarns.

Stretch Denim

Modern denim often includes elastane (Lycra/spandex) for stretch. Small percentages (1-3%) add comfort and recovery without significantly changing the denim character. Higher percentages (5%+) create very stretchy fabric that some find comfortable but others feel lacks authentic denim character.

For shorts, a small amount of stretch can enhance comfort, especially in fitted styles. The stretch allows movement without the break-in period rigid denim requires.

Dye and Finishing

Indigo dyeing gives denim its characteristic blue colour and fading properties. Traditional rope dyeing dips yarn repeatedly into indigo baths, building colour in layers. This method allows the indigo to penetrate only the outer layers of yarn, leaving cores white—which is why denim fades to reveal lighter tones underneath.

Sanforisation

Most modern denim is sanforised—pre-shrunk using a controlled process. Unsanforised (shrink-to-fit) denim shrinks 5-10% when first washed, requiring you to buy larger and shrink it to fit. Most casual shoppers prefer sanforised denim for predictable sizing, though enthusiasts sometimes prefer unsanforised for its traditional character.

Washing and Finishing

The wash applied to denim dramatically affects its appearance. Raw or dry denim is unwashed, stiff, and dark. Rinsed denim has been washed once to remove surface starch. Various wash treatments (stone-washing, enzyme washing, laser distressing) create pre-worn appearances of varying authenticity.

Applying This Knowledge

Understanding denim construction helps you evaluate options and find what suits your preferences. For denim shorts specifically:

• Prioritise appropriate weight for your climate—don't sacrifice comfort for prestige
• Consider stretch content based on your fit preference and activity level
• Examine construction details like stitching, rivets, and seam finishing
• Don't assume price always correlates with quality—evaluate each pair on its merits

Armed with this knowledge, you can confidently assess denim quality and make purchases that satisfy both immediately and over years of wear.