What Is Loop-Back Fleece? The Complete Guide
Loop-back fleece is a knit fabric construction with a smooth face on the exterior and a brushed, looped surface on the interior. It is the standard construction for premium heavyweight sweatshirts and hoodies — chosen for its warmth retention, durability, and the way it softens with wear rather than degrading.
What is loop-back fleece?
Loop-back fleece — also called loopback fleece or loop-back terry — is a weft-knit fabric construction. The exterior surface is smooth and compact. The interior surface is left with uncut yarn loops, created during the knitting process, which are then lightly brushed to produce a soft, insulating layer against the skin.
The name comes from the construction method: during knitting, a secondary yarn is fed in and forms loops on the reverse side of the base fabric. These loops are not cut — unlike in polar fleece, where the loops are cut and brushed into a pile. The intact loops in loop-back fleece are what give it its durability and its characteristic soft-but-structured hand-feel.
How loop-back fleece is made
Loop-back fleece is produced on a circular knitting machine. Three distinct layers are formed simultaneously: the smooth face yarn on the exterior, the structural knit base in the middle, and the loop yarn on the interior. The loop yarn is fed at a longer length than the face yarn, which causes it to form loose loops on the reverse side of the fabric.
After knitting, the fabric is washed and the interior is lightly brushed — a process called raising — to open the loops slightly and create a softer surface. The loops remain intact throughout. According to the Textile Institute, this intact-loop construction is what distinguishes loop-back fleece from cut-pile alternatives: the uncut loops retain structural integrity through repeated washing and wear cycles, resisting the surface degradation that causes cheaper fleece to pill and flatten.
Loop-back fleece vs French terry vs polar fleece
Loop-back fleece — intact interior loops, smooth exterior, 350–420gsm typical range. Warm, structured, durable. The correct construction for heavyweight sweatshirts and hoodies.
French terry — similar loop construction but lighter, typically 200–280gsm. The loops are less dense and the fabric is thinner. Better suited to summer-weight or transitional garments. Not a heavyweight fabric.
Polar fleece — the loops are cut and brushed into a pile on both sides. Lighter and softer initially, but the cut pile degrades faster — pilling and flattening with repeated washing. Typically synthetic (polyester). Not the same category as loop-back fleece.
The distinction matters when buying. A brand that describes a garment as "fleece" without specifying loop-back construction may be using polar fleece or a blended alternative. Loop-back fleece is the premium standard — and it should be stated explicitly on the product page.
Why GSM matters in loop-back fleece
GSM — grams per square metre — measures fabric density. In loop-back fleece, a higher GSM means more yarn per unit area: denser loops on the interior, a heavier face yarn on the exterior, and a more substantial knit base. The result is a garment that holds its structure, retains warmth more effectively, and resists surface wear over time.
The practical GSM ranges for loop-back fleece: 280–320gsm is mid-weight — adequate for mild conditions, lighter in hand. 350–380gsm is genuine heavyweight — structured, warm, season-spanning. 400gsm+ is premium heavyweight — the fabric has a drop weight, holds a silhouette, and performs across autumn and winter without a mid-layer.
Most high-street sweatshirts sit at 240–300gsm. The difference between a 280gsm and a 400gsm loop-back fleece garment is not subtle — it's a different category of product.
Ring-spun vs open-end yarn in loop-back construction
The yarn type used in loop-back fleece determines the quality of both the face and the interior loops. Ring-spun cotton is produced by continuously twisting and drawing out fibres into a tight, smooth, consistent yarn. Open-end cotton is produced faster by a rotor-spinning method that creates a coarser, less uniform yarn with more protruding fibres on the surface.
In loop-back fleece, ring-spun yarn produces a smoother face, tighter and more even interior loops, and significantly better resistance to pilling. The Cotton Incorporated Lifestyle Monitor data consistently shows that ring-spun cotton garments outperform open-end alternatives in consumer wash-durability testing — retaining appearance and hand-feel through significantly more wash cycles.
Open-end yarn is cheaper to produce. It is the correct choice for budget basics. It is not the correct choice for a 400gsm premium heavyweight garment.
How echelonn. uses loop-back fleece
Both the aegis. and the thorax. are built from 400gsm loop-back fleece, 100% ring-spun cotton. No polyester. No spandex. The loop construction is the same across both garments — the difference is silhouette: the aegis. is a heavyweight hoodie with a structured hood and kangaroo pocket; the thorax. is a crewneck sweatshirt with a dropped shoulder and ribbed cuffs and hem.
Both are enzyme-washed before they ship — a controlled wash process that pre-shrinks the fabric and softens the surface without compromising the loop structure. The fit you receive is the fit it keeps. We made 200 units of each. We don't restock.
"Ring-spun yarns demonstrate measurably superior tensile strength and surface uniformity compared to open-end spun alternatives, making them the preferred choice for premium fleece construction." — Textile Institute
FAQ
What is loop-back fleece?
Loop-back fleece is a knit fabric construction with a smooth exterior face and an interior surface of uncut yarn loops. The loops are formed during knitting and lightly brushed after washing. It is the standard construction for premium heavyweight sweatshirts and hoodies.
Is loop-back fleece the same as French terry?
No. Both have a looped interior, but French terry is significantly lighter — typically 200–280gsm — and the loops are less dense. Loop-back fleece is heavier, warmer, and more structured. French terry is a transitional or summer-weight fabric; loop-back fleece is a heavyweight winter construction.
What GSM should loop-back fleece be for a heavyweight sweatshirt?
350gsm is the minimum for genuine heavyweight. 400gsm is the premium standard — dense enough to hold structure, warm enough to replace a light jacket, and durable enough to maintain its appearance through repeated washing.
Why is ring-spun cotton better in loop-back fleece?
Ring-spun cotton produces a tighter, smoother, more consistent yarn than open-end cotton. In loop-back fleece, this means a smoother face, more even interior loops, and significantly better resistance to pilling and surface degradation over time.
Does loop-back fleece shrink?
Untreated loop-back fleece will shrink on first wash. Premium garments are enzyme-washed or garment-washed before shipping — a controlled pre-shrink process that stabilises the fabric. Always check whether a garment has been pre-washed before buying.
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echelonn. aegis. + thorax. 400gsm loop-back fleece · 100% ring-spun cotton · enzyme-washed · HQ 001 · 200 units aegis. → add to formation thorax. → add to formation |