The Fabric & GSM Handbook: Choosing the Right Base for Printed Apparel

Almost every disappointing apparel order can be traced back to a fabric decision that was made by default rather than on purpose. The print method gets debated for days; the base cloth gets chosen because someone said “180 GSM” once and it stuck.

This handbook is what our sourcing team explains on the first call. It covers what GSM does and does not tell you, how knit construction changes the way ink behaves, which fibres survive which processes, and how to write a fabric specification precise enough that two different suppliers would produce the same thing.

What GSM actually measures

GSM is grams per square metre. It is a measure of weight — nothing more. A square metre of the fabric, weighed. It says nothing directly about softness, durability, shrinkage, or how well a fabric takes ink.

This is worth being blunt about, because GSM is routinely used as a proxy for quality in marketplaces and it is a poor one. A 220 GSM open-end carded cotton tee will feel rougher, pill faster and print less sharply than a 180 GSM combed ring-spun one. The heavier fabric is heavier. That is all you learn.

GSM tells you how much fabric there is. Yarn type, knit and finish tell you how good it is.

What GSM does reliably predict:

• Opacity. Below about 150 GSM, white and light garments become see-through, which matters more than most buyers anticipate.
• Drape. Lighter fabric hangs closer to the body; heavier fabric holds structure and boxy silhouettes.
• Warmth and season fit. A 330 GSM fleece is a winter product, whatever else is true about it.
• Shipping cost. On a 2,000-piece order the difference between 160 and 200 GSM is real money in freight.

The weight bands that matter

For a printed t-shirt intended for daily wear, 160–190 GSM single jersey in combed ring-spun cotton is the sweet spot and has been for a decade. It is opaque, it drapes, it prints cleanly with every method, and it does not feel like a giveaway.

Knit construction, explained properly

Knit structure determines surface texture, stretch, and how flat the fabric lies under a press — which is exactly what determines print sharpness.

Single jersey

The standard t-shirt knit. Smooth face, looped back, moderate stretch across the width. It is the flattest common surface, which is why it prints better than anything else. Curls at raw edges, which is a cutting consideration rather than a wearing one.

Pique

The textured, waffle-like knit used for polo shirts. Its raised surface breathes well and hides creasing, but the texture means fine print detail breaks up. Embroidery is the natural decoration for pique, and it is why corporate polos are almost always embroidered rather than printed.

French terry

Smooth face, looped back, no brushing. Softer and lighter than fleece, wearable year-round, and increasingly the preferred hoodie fabric in warm climates. Prints well on the face side.

Fleece (brushed back)

French terry with the back loops brushed into a soft nap. Warmer, heavier, and the classic winter hoodie. The face still prints cleanly; the brushing is on the inside.

Interlock

Double-knit — smooth on both sides, denser, more stable, less prone to curling. Common in premium polos, kidswear and anything where both faces are visible.

Rib

Vertical ridges with strong crosswise stretch and recovery. Used for collars, cuffs and waistbands rather than whole garments. Never print across a rib and expect the graphic to stay square.

Fibres: cotton, polyester, blends and the rest

Cotton

Breathable, absorbent, comfortable, and the only common fibre DTG can bond to properly. It also shrinks, creases, and dries slowly. Within cotton the important distinctions are:

• Carded (open-end) — shorter fibres, cheaper yarn, rougher surface, more pilling. Fine for giveaways.
• Combed — short fibres removed before spinning. Smoother, stronger, prints sharper.
• Ring-spun — yarn twisted continuously, producing a finer and softer thread. Combed ring-spun is the standard for good retail tees.
• Organic — grown without synthetic pesticides; meaningful only when certified (see our sustainability guide).

Polyester

Strong, dimensionally stable, quick-drying, moisture-wicking and the only fibre sublimation works on. It is less breathable in still air and holds odour more readily than cotton, which is why performance polyester is usually treated with an anti-microbial finish. Recycled polyester (rPET) performs identically to virgin for apparel purposes.

Blends

• 65/35 poly-cotton — the workhorse uniform fabric. Durable, low shrinkage, holds a press.
• 50/50 — softer than it sounds, popular for retail; DTG colour comes out muted.
• Tri-blend (cotton/poly/rayon) — exceptionally soft with a heathered look and beautiful drape. Prints with a slightly vintage, textured finish because the fibres take ink differently.
• Cotton/elastane (95/5) — added stretch for fitted garments. Rigid prints must be kept small or they will crack.

Viscose, modal, bamboo, linen

All produce a beautiful drape and hand-feel. All are more delicate under heat presses and require careful temperature control. Excellent for fashion products, less appropriate for uniforms that need to survive institutional laundry.

Finishes that change everything

Two fabrics with identical fibre, yarn, knit and GSM can behave completely differently because of finishing. The ones you should know about:

• Bio-wash / enzyme wash — enzymes remove surface fuzz. The fabric becomes smoother, softer, less prone to pilling, and noticeably better at holding fine print detail. For DTG it is close to essential.
• Compacting — mechanical pre-shrinking. Reduces post-wash shrinkage from 7–8% to around 3%. If your garment must hold its size, specify compacted fabric.
• Mercerisation — a caustic treatment that swells cotton fibre, increasing lustre, dye uptake and strength. Gives that subtle sheen on premium polos.
• Peach finish — a light brushing for a suede-like surface. Lovely to touch, but it raises fibres that can soften fine print edges.
• Moisture management / wicking — a chemical finish on polyester that moves sweat to the surface. Survives roughly 30–50 washes on most treatments.
• Anti-microbial — reduces odour-causing bacteria. Useful in sportswear and healthcare uniforms.

Our stock fabric reference table

Choosing fabric by use case

Corporate uniform, worn three days a week for two years

200 GSM 65/35 poly-cotton, compacted. Low shrinkage, holds a press, survives institutional laundry, and embroidery sits on it beautifully. Do not chase softness here — chase dimensional stability, because your buyer's real problem is that the size 40 shirts must still be size 40 next March.

Retail t-shirt with a graphic front

180 GSM combed ring-spun single jersey, bio-washed. It is the fabric that makes a printed tee feel like a product rather than a promotional item, and it takes every print method well.

Sports jersey

140–160 GSM performance polyester with a wicking finish, sublimated. Anything else is a compromise: cotton holds sweat, and applied prints add weight and block airflow exactly where an athlete needs it least.

Streetwear drop

220 GSM heavy jersey, compacted, in an oversized block pattern. The weight is the aesthetic. Pair with high-density screen printing or puff for the texture that the category expects.

Event giveaway, 2,000 pieces, tight budget

150–160 GSM carded cotton, one-colour screen print. Be honest with yourself about the lifespan — this garment exists for a weekend and a photograph, and paying for combed ring-spun yarn is money that will not be noticed.

Fabric faults and what they cost you

Fabric arrives with defects. A competent manufacturer inspects and rejects; an incompetent one cuts around them and hopes. The common ones:

• Barré — horizontal streaking caused by yarn inconsistency. Invisible on the roll, obvious on a finished white tee under shop lighting.
• Shade variation — different dye lots in a single order. This is the most common complaint in repeat corporate orders and is why we hold your specific lot.
• Holes and needle lines — knitting faults, usually running lengthwise.
• Spirality — the side seam twists after washing, caused by unbalanced yarn twist. Devastating in uniforms and entirely a fabric-selection problem.
• Excess shrinkage — uncompacted fabric can lose 7–8% in the first wash, which turns a size L into an M.

We inspect incoming fabric using a four-point system and check GSM, shrinkage and spirality on every lot before cutting. That step is why our lead times include a day that other quotes do not.

How to write a fabric spec

Five elements. Include all of them and any competent factory in the world will make you the same cloth:

1. Fibre and blend ratio — “100% cotton” or “65% polyester / 35% cotton”.
2. Yarn — “30s combed ring-spun”.
3. Knit — “single jersey”, “pique”, “French terry”.
4. Weight — “180 GSM ±5%”.
5. Finish — “bio-washed, compacted, shrinkage max 3%”.

A complete spec looks like: 180 GSM ±5% single jersey, 100% combed ring-spun cotton, 30s count, bio-washed and compacted, max shrinkage 3%, colour per approved lab dip.

That last clause matters as much as the rest. A lab dip is a small sample of the fabric dyed to your target colour and approved before bulk dyeing begins. Approving a lab dip is the only reliable way to control colour, and skipping it is how brands end up with two slightly different navies in one collection.

What to read next

Fabric constrains print method more tightly than most buyers expect — polyester rules out DTG, dark garments rule out sublimation, and pique texture rules out fine detail. The printing methods comparison maps those constraints in full. If you are costing an order, the MOQ economics guide explains why fabric choice affects your minimum quantity as much as your print method does.

Or bring the question to us: tell us what the garment has to do and how long it has to last, and we will specify the cloth.