Sewn-bottom / open-mouth
The classic flour sack. Filled through the open mouth and closed with thread or adhesive. Flexible on sizes and easy to run on simple filling equipment.
Application · Food
Flour paper bags built for 25 kg filling lines
Multi-wall kraft paper sacks for wheat flour, bakery premixes, semolina, starch and food ingredients — printed in our own factory and produced in a food-grade workshop.
What We Supply
One bag type, many flour applications
Flour mills and food-ingredient producers need a bag that stands on the pallet, survives the drop from the filling spout, and keeps moisture out during a long sea voyage. The structure below is the one we build most often for 22.7 kg and 25 kg fills.
- 2–5 plies of kraft or white paper, 70–110 gsm per ply
- Food-grade PE inner liner 0.04–0.07 mm where moisture matters
- Sewn bottom, pasted square bottom or valve filling
- Inner and outer reinforcement strips for heavy stacking
- Flexo print in 1–8 colours, including barcodes and batch panels
Specifications
Common flour bag structures
These are the configurations we produce most often. Your exact size is confirmed against your filling machine and product bulk density.
| Structure | Typical size | Fill weight | Best for |
|---|---|---|---|
| 3-ply kraft, 80 gsm, sewn bottom | 85 × 49.5 × 10 cm | 25 kg | Wheat flour and bakery flour on standard filling lines |
| 3-ply kraft, 80 gsm, sewn bottom | 81 × 49.5 × 10 cm | 22.7 kg | Export flour packs sold in 50 lb markets |
| 3-ply kraft + PE liner | Built to your fill weight | 20–30 kg | Sugar, starch, semolina, oats and additives |
| 3-ply kraft, valve filling | 57 × 50 × 14 cm | 25 kg | High-speed valve filling with tidy pallet stacking |
| 4–5 ply kraft, reinforced bottom | Built to your fill weight | 40–50 kg | Long sea transit, rough handling, high stacking |
Filling Method
Sewn bottom or valve filling?
Both types are produced in-house. The choice depends on your filling line and how the bag is handled after filling.
Valve filling
Filled through a paper, inner/outer or ultrasonic valve. Faster on automatic lines, less dust, and the flattened valve keeps the pallet tidy.
Not sure which fits your line? See the comparison in valve bag vs open-mouth bag, or send us a photo of your filling spout.
Food Safety
Produced in a food-grade workshop
Flour and food-ingredient customers are audited on what the bag is made of and where it is made. Our production for food-contact packaging runs with separate raw material storage, documented process control and food-contact compliant paper and ink selections.
- ISO 9001 quality management and ISO 22000 food safety management
- HACCP-based process control on the food-grade line
- Food-contact compliant paper, film and ink selection
- Certificate documents supplied with quotations on request
FAQ
Flour paper bag questions
What size is a standard 25 kg flour bag?
A common 25 kg flour bag is a 3-ply, 80 gsm kraft bag of roughly 85 × 49.5 × 10 cm with a sewn or pasted bottom. The final size is confirmed against your filling machine and the bulk density of your flour.
How many plies do I need?
Most 25 kg flour bags use 3 plies at 80 gsm. Two plies suit lighter or short-distance fills; 4 plies are used for longer sea transit, higher stacking or rougher handling.
Do flour bags need a PE inner liner?
A food-grade PE liner of 0.04–0.07 mm is recommended when flour is stored in humid conditions or shipped in containers for several weeks, because it blocks moisture that paper alone cannot stop.
Can you print our brand and barcode?
Yes. Flexographic printing runs from 1 to 8 colours, including brand artwork, barcodes, batch panels and multi-language text. Artwork is checked against the bag structure before sampling.
What is the MOQ and sample lead time?
MOQ depends on bag size, structure and print colours, and sample lead time is confirmed with your quotation once artwork is approved. Send your specification and we will confirm both within one working day.
Tell us your flour bag specification
Send length × width × gusset, fill weight, plies, liner, printing and quantity. We will advise the structure and quote within one working day.