What a non-woven bag actually is
The classic reusable “green bag” handed out at supermarkets, trade shows and retail checkouts is almost always made from spunbond non-woven polypropylene (PP). Unlike a canvas tote — where cotton yarns are woven over and under each other — non-woven fabric has no threads. Molten polypropylene is extruded into fine continuous filaments, laid randomly onto a moving belt, then bonded together with heat and pressure into a single sheet. The result feels like a soft, slightly papery felt. It is light, surprisingly strong for its weight, tearable but not easily, and cheap to produce at scale — which is exactly why it dominates the promotional and grocery bag market.
Because there is no weave, the fabric can be cut, folded and welded together with heat or ultrasonic sound instead of needle and thread. That single fact drives most of the cost, speed and design decisions below.
Fabric weight (gsm): the first spec that matters
Non-woven PP is sold by weight per square metre — grams per square metre, or gsm. This is the single most important number on your spec sheet, because it governs how sturdy the bag feels and how much it costs. Heavier fabric uses more raw polypropylene, so price scales almost directly with gsm.
| Fabric weight | Feel & typical use | Trade-off |
|---|---|---|
| 40–50 gsm | Thin, low-cost giveaway bags for light contents | Cheapest, but flimsy and short-lived |
| 60–70 gsm | The common workhorse for promo & event totes | Good balance of price and durability |
| 80–90 gsm | Retail-quality reusable shoppers, grocery bags | Noticeably sturdier, higher cost |
| 100–120 gsm | Heavy-duty bags, wine carriers, premium reusables | Most durable, closest in cost to woven totes |
A useful rule of thumb: below 60 gsm the bag reads as disposable; 80 gsm and above reads as reusable. If a buyer wants the bag kept and reused — the whole point of the eco story — it is worth paying for the heavier cloth.
Plain vs laminated non-woven
Standard non-woven fabric is matte and slightly porous. For a glossier, more premium look — and for water resistance and print sharpness — a thin transparent film is heat-laminated onto the surface. This gives you two families:
- Plain (non-laminated): matte finish, breathable, fully recyclable as a single material, lowest cost. Best printed with simple silk-screen logos.
- Laminated: a glossy or matte BOPP film bonded to the face. It wipes clean, resists light rain and allows photographic, full-colour print. Common on retail shoppers and gift bags where shelf appeal matters.
The honest trade-off: lamination looks and performs better, but it adds a second material layer, which raises cost and makes end-of-life recycling less clean than plain PP. It is water resistant, not waterproof — seams and needle holes still let water through, so we never rate these bags for immersion or heavy rain.
How the bag is assembled: welded vs stitched seams
Here is where non-woven differs most from a fabric tote. Because polypropylene is a thermoplastic, panels can be fused rather than sewn.
- Heat-sealed / ultrasonic-welded seams: the standard method. Ultrasonic vibration or a hot tool melts the two layers together along the seam in one fast pass. No thread, no needle holes, extremely fast, and it suits automated or semi-automated lines. The vast majority of low-cost promo bags are welded.
- Stitched (sewn) seams: the panels are sewn on a sewing machine exactly like a cloth bag. This is stronger and looks more like a “real” bag, and it is the norm for heavier 90–120 gsm reusables and any bag that must carry serious weight. It costs more because it is slower and labour-based.
Welded seams win on price and speed; stitched seams win on strength and perceived quality. Many mid-range bags mix the two — welded body, stitched handles — to get the best of both.
Shape and handles: box vs flat, and how you carry it
Two structural choices define how a non-woven bag looks and how much it holds:
- Flat bag: two panels sealed at the sides and bottom, no gusset. Cheapest, lies flat, limited capacity. Good for documents, flyers and lightweight giveaways.
- Box bag (gusseted): side and bottom gussets give the bag depth so it stands up and holds boxed goods, groceries or wine bottles. This is the grocery-shopper shape and the most useful for genuine reuse.
Handles come in three main styles. Soft loop handles are made from the same non-woven fabric, welded or sewn on — cheapest and most common. Die-cut handles punch a hole straight through a reinforced top hem — ultra cheap, but only for light loads. Sewn webbing or long shoulder handles add real load capacity and a retail feel at extra cost. Match the handle to the weight the bag will carry, not just the look.
Print and branding methods
How you decorate the bag depends on how many colours you need and whether the fabric is laminated:
- Silk-screen printing: the workhorse for plain non-woven. Excellent for 1–4 solid spot colours and logos. Cheap at volume; each extra colour adds a screen and cost.
- Heat-transfer / thermal transfer: good for more detailed or multi-colour art on smaller runs.
- Full-colour gravure / offset lamination: the film is printed photographically before it is laminated to the fabric, giving edge-to-edge, full-colour, magazine-quality graphics. This is the premium retail look and needs a laminated construction.
For most B2B promo and grocery programs, an 80 gsm plain box bag with a two-colour silk-screen logo hits the sweet spot of cost, durability and brand visibility.
The eco angle — honestly framed
Non-woven PP bags are marketed as the reusable, eco-friendly alternative to single-use plastic, and there is a real case for it: polypropylene is a type-5 plastic that is recyclable, the bags are durable enough for dozens or hundreds of uses, and a heavier bag reused many times displaces a lot of thin checkout bags. The genuine environmental benefit comes from reuse, so specifying a fabric heavy enough to survive real use (80 gsm+) matters more than any label. Plain, un-laminated bags are the cleanest to recycle because they are a single material. We are careful not to overstate this — a bag that is too thin to be reused undercuts the whole story.
How SYMPATHYBAG makes this
At Guangzhou Ceyin Bags we produce non-woven PP shoppers across the full 40–120 gsm range, plain or laminated, welded or fully sewn, in flat or gusseted box shapes with your choice of handle. Our factory in Baoding runs three workshops with 150+ sewing machines and can turn out up to 50,000 bags a month, so large promotional and retail programs scale comfortably. MOQ is generally 500 pieces per design and colourway, and simple promotional bags can sometimes start lower, around 200–300 pieces. Development samples for VIP projects are free in about three days; standard samples are US$98 in about seven days and refundable against your order. Every run passes our four-stage in-line QC (IQC, IPQC, FQC, OQC) and we welcome AQL and third-party inspection. When contents will touch food or reach children’s markets, we can arrange testing through accredited labs (REACH, Prop 65, CPSIA and similar). See our OEM / ODM capabilities, browse bag categories, or send your spec for a quote.
