Two quotations land on your desk. Both say 150 gsm kraft. Same size, same print, same quantity. One is fourteen percent cheaper.Take the cheaper one and you may have bought a bag that carries a third less weight, because grammage measures the weight of the paper, not its strength. One quote is virgin kraft, the other recycled, and nothing on either document tells you which. The number everyone negotiates is rarely the number that decides whether the bag works.This part covers what does: the paper, the construction, the handle and the glue.
This is the first part of the full paper bags purchase guide by Simmy Lin, Managing Director at BK-Bags, a leading supplier of paper bags and reusable shopping bags, producing in Vietnam and China since 2006.
Paper bags for retail are made from kraft paper, ivory board, art paper or wood-free paper, specified by grammage in g/m² (commonly 120 to 250 gsm for carrier bags), by fibre source (virgin or recycled), by construction (square bottom or side gusset, machine-made or handmade) and by handle type (twisted paper, flat paper, cotton rope, PP rope, ribbon or die-cut). Grammage measures weight per square metre, not strength: at the same gsm, virgin kraft carries substantially more than recycled kraft because its fibres are longer. Load capacity is a construction property, set by the bottom, the depth of the top turnover and how the handle is attached, not by paper weight alone.
In This Article:
Key Takeaways
- Grammage is weight, not strength. At equal gsm, virgin kraft outperforms recycled kraft by roughly a quarter to a third.
- “Wood-free” paper is made from wood. The term means chemical pulp, not tree-free, and it is not an environmental claim.
- Most paper bags fail at the handle, not in the paper. Ask about the reinforcement patch before you ask about the price.
- Machine-made and handmade are two different products. A quotation that does not say which is not comparable to one that does.
- If the bag is laminated, the lamination has already chosen your glue. Water-based adhesive will not bond to it.
1. The four paper grades
Kraft paper. Made by the kraft (sulphate) chemical pulping process, which is where its strength comes from. Brown is unbleached, white is bleached, and coloured krafts are dyed in the pulp rather than printed, which is why the colour survives a scuff. Kraft is the default for grocery, food service and everyday retail because it takes load better than anything else at the same weight.
Ivory board is coated one side, smooth and bulky, common at 210 to 300 gsm. Art paper is coated both sides for the highest print fidelity, at 128 to 200 gsm, then laminated or assembled by hand, because art paper alone lacks the stiffness to hold a carrier bag shape.
Wood-free paper is the most misleading name in packaging. It is made from wood. The term means the pulp is chemical rather than mechanical, so the lignin has been removed. It says nothing about whether trees were used and it is not an environmental claim.
| Grammage | Typical use | Notes |
| 80 to 120 gsm | Bakery, pharmacy, food service, small merchandise | Often flat or die-cut handle, or none |
| 120 to 170 gsm | Everyday retail carrier, fashion, grocery | The volume band for most retail programmes |
| 170 to 210 gsm | Mid-premium retail, gift, heavier loads | Where ivory and art paper start |
| 210 to 300 gsm | Luxury retail, rigid-feel bags, boxes | Usually handmade, laminated, often board-reinforced |
A caution on recycled grades for food contact. Recycled fiber carries whatever was in the paper’s previous life, including mineral oil residues from printing inks. For direct food contact, specify virgin fiber or a barrier layer and ask for a food-contact declaration. A recycled grade that suits a fashion bag does not necessarily suit a bakery bag.
2. Grammage is not strength
Grammage, written gsm or g/m², is the weight of one square meter of paper. It is the number every quotation leads with, and on its own it is not a strength specification. This is why “150 gsm kraft” is not a specification. A complete paper line reads:
grade · grammage · fibre source · finish · certification claim
For example: brown kraft, 150 g/m², 100% virgin softwood, machine glazed one side, FSC Mix 70%.
If a quotation gives you the first two only, you cannot compare it to anything.
3. How the bag is built
The bottom
Square bottom (SOS, self-opening sack) is the retail standard, because the bag stands up on its own. Side gusset folds flat on both sides: cheaper, packs flatter, less stable standing. Flat or pinch bottom has no standing base. A cardboard bottom insert is the cheapest way to carry weight without the base folding: specify glued in or loose, because a loose one falls out and a glued one is a priced component.
The top
The turnover, or hem, is the top edge folded over and glued. It stops the mouth of the bag tearing and it is where the handle anchors. Ask how deep it is. A shallow turnover is a common cost saving and the reason handles tear out through the top edge. A top stiffener, a card strip inside the turnover, is standard on premium handmade bags.
Machine-made and handmade
Machine-made bags run on automatic bag lines: paper printed on the reel by flexography, then formed, glued and the handle applied inline. Fast, consistent, low unit cost at volume, and how kraft carriers and food bags are produced.
Handmade bags start as printed sheets, usually offset on art paper or ivory board, often laminated, then cut, folded, glued and handled by hand. The only route to precise offset colour, full-bleed images, lamination, foil, embossing and knotted rope.
4. Handles, and how they are attached
Most paper bag complaints are handle failures. The paper is usually fine.
| Handle | How it is made | Notes |
| Twisted paper | Paper rope formed and applied inline on the bag machine | The workhorse. All-paper, recyclable, low cost at volume |
| Flat paper | Flat paper tape | All-paper, comfortable across the hand, common on kraft carriers |
| Cotton rope or ribbon | Applied by hand, knotted or glued | Premium feel. Not paper, which matters in the recycling stream |
| PP rope | Applied by hand, usually knotted | The cheapest premium-look handle. It is plastic |
| Die-cut | Punched through the bag itself | No added component, no added cost, least comfortable to carry |
Attachment is the specification that matters
- Glued patch handle. A reinforcing paper patch glued over the handle ends inside the bag. The strong version.
- Direct glue, no patch. Handle ends glued straight to the turnover. Cheaper, weaker, and the usual cause of a handle pulling through.
- Knot through a punched hole. Strong if the hole is reinforced, a tear line if it is not.
- Aglet or t-bar. A bar on the handle end sitting inside the bag against the panel. Distributes load well.
Ask for the patch. Ask whether the hole is reinforced. Both cost a fraction of a cent and they decide whether the bag gets home.
The plastic handle question
A PP rope handle is polypropylene, and it changes three things at once. It has to be removed before the bag enters the paper stream, and most people do not remove it. It counts against the EU design-for-recycling grade that applies from 2030. And it creates no US tariff exclusion: the antidumping order on paper shopping bags excludes certain bags with handles made wholly of woven ribbon or similar woven fabric, and its own footnote states that braided or twisted rope or cord does not qualify.
5. Glue: the specification nobody quotes
Adhesive never appears on a purchase order and it decides two things: whether the bag holds together in a humid container, and whether it can be recycled cleanly.
Starch and dextrin (water-based). The traditional bag adhesive. Fully repulpable, cheap, best for recyclability. Slower setting, and it will not bond to a laminated or varnished surface.
PVA cold glue (water-based). Used on handmade bags and lamination. Dries clear, strong on uncoated paper, repulpable.
EVA hot melt. Sets in seconds, which is why high-speed bag lines use it for bottoms and handles, and it bonds to coated and laminated surfaces where water-based glue will not. It softens with heat, a real risk in a container crossing the equator.
PUR hot melt. Reactive polyurethane. Strongest and most heat resistant, most expensive, and hardest on the recycling stream.
If your bag is laminated, water-based glue will not hold it, so the lamination decision has already made the glue decision. And if your containers cross hot routes or sit at a port in summer, say so before the quote. That is a hot-melt specification question, and it is cheaper to answer in advance than after a container of unstuck bottoms arrives.
6. Load capacity and how to test it
EN 13590:2003 covers test methods for determining the volume and carrying capacity of flexible carrier bags. The test loads the bag and lifts it repeatedly, with the required load scaled to its volume. The industry guideline from CEPI Eurokraft and EUROSAC, published by the European Paper Bag Association, is that a high-quality paper carrier should carry at least 6 kg home from the supermarket and be reusable up to five times.
load capacity is a construction property: it comes from the bottom, the depth of the turnover, and the handle attachment.
7. Twelve questions to ask your supplier
The paper
- What grade is the paper: kraft, ivory, art, wood-free or other? State it exactly.
- What is the grammage in g/m², and is that the base paper or the finished laminated weight?
- Is the fibre virgin, recycled or blended, and what percentage?
- Can you provide mill test data for tensile and burst on this grade?
- Is the paper suitable for food contact, and can you supply a declaration?
Construction
- Square bottom, side gusset or flat bottom, and is there a bottom board?
- How deep is the top turnover, and is there a top stiffener?
- Machine-made or handmade? This changes the print options and the price.
Handles
- Handle type and exact material. If it is rope, is it paper, cotton or PP?
- How is the handle attached: glued patch, direct glue, knot through a hole, or aglet? Is the punch hole reinforced?
- What is the tested load capacity of the finished bag, and by what method? Has it been tested to EN 13590?
Glue
- Which adhesive system, what is its heat resistance, and has this construction shipped on hot routes before?
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Next in this series: Part 2, printing and finishing paper bags · Part 3, certification, regulation and import duties
