PP woven sacks for flour, sugar and rice

Flour, sugar and rice are usually packed in woven polypropylene (PP) sacks because the fabric is strong for its weight, resists tearing and stacks well. The three products do not ask the same of a sack, though: flour is a fine powder that can sift through a weave, sugar and rice are granular, and all three must stay dry.

Key definitions

• Woven fabric. Flat polypropylene tapes interlaced at right angles, usually into a seamless tube on a circular loom. A closer weave leaves smaller gaps between the tapes.
• Fabric weight (GSM). Grams per square metre of fabric. More grams means more polypropylene: as a rule a stronger, stiffer and more expensive sack.
• Liner. A separate bag of thin polyethylene film inside the woven sack. It holds fine powder in and slows moisture.
• Lamination. A thin plastic coating bonded to the fabric, closing the gaps between the tapes.
• Hemmed top. The cut edge of the mouth, folded over and sewn so that it does not fray. A heat-cut top is sealed instead by the hot blade that cuts it.
• Stitched bottom. The bottom of the tube, folded and sewn shut.
• Sifting. Fine product escaping between the tapes or through the needle holes of a seam.

Why woven polypropylene is the usual sack

The strength comes from the tapes: polypropylene film is slit into narrow tapes and stretched, which gives each tape its tensile strength (see the factory page). Woven fabric alone is not a barrier, though: air and humidity pass between the tapes. That lets a filled sack release trapped air, and it is why liners and lamination exist.

How flour, sugar and rice differ as contents

Product	How it behaves	What matters most	What to ask the supplier
Flour	Fine powder that holds air after filling	Sifting; moisture	Closeness of the weave, the bottom seam, a liner or lamination
Sugar	Free-flowing crystals that cake when damp	Moisture	A liner, and how the sack is closed over it
Rice	Grains too large to sift	Dryness; a clear brand and grade	Print and stripes; a liner or lamination for humid routes

Flour is the demanding one. It can work through a weave and through the needle holes of the bottom seam. A closer weave, a liner or laminated fabric each reduce sifting. A liner or lamination also stops the fabric breathing, and freshly filled flour holds air, so tell the supplier how you fill and close your sacks.

Sugar and rice do not sift as flour does. Their risk is moisture: sugar draws it from humid air and sets into lumps, and damp rice turns musty.

Liners and lamination are trade options that not every maker supplies. Ask what your supplier can provide, then test sample sacks on your own filling line.

White fabric, print and coloured stripes

White is the usual ground for staple sacks: the fabric looks clean and shows a printed brand clearly. Al-Sharq Plastic Manufacturing Company makes white PP woven bags to the size ordered, unprinted or printed with the buyer’s design.

A mill that packs several grades or weights in the same white sack can tell them apart with coloured stripes. The stripes are woven in, not printed: coloured tapes run with the white ones on the loom and show as lines along the length of the sack. One colour per grade, or one for the 25 kg sack and another for the 50 kg sack, can be read from across a warehouse.

Size follows the fill weight and the product’s bulk

A sack is specified from two things: the fill weight, and the room that weight of product takes up. Common fill weights for flour, sugar and rice are 25 kg and 50 kg. Flour is lighter for its volume than sugar or rice, so the same weight needs a roomier sack. Every sack also needs spare length above the product so that the mouth can be closed, usually by sewing.

If a sack you already use works, measure it flat and send the width and length. If not, ask the supplier to propose a size.

How to specify a sack, step by step

1. Product and fill weight. For example: wheat flour, 50 kg per sack.
2. Size. Width and length of the flat sack, in centimetres.
3. Protection. How long the sacks are stored, how humid the route is, and whether a liner or lamination is advised and available.
4. Fabric colour. White, or white with coloured stripes and the colour for each grade or weight.
5. Print. Unprinted or printed, with the artwork and its position.
6. Top and bottom. Hemmed or heat-cut top, and how you close the sack after filling.
7. Quantity and destination. The number of sacks, whether the order will repeat, and the place of delivery.

Steps 1, 2, 4, 5 and 7 cover the six details Al-Sharq needs to prepare a quotation.

Storing and stacking sacks

Keep empty and filled sacks under a roof, dry and off the floor on pallets. Keep them out of direct sunlight: polypropylene degrades under prolonged sun unless it is UV-stabilised, so ask the supplier about UV stabilisation if your sacks will stand outdoors. Build stacks in interlocking layers so that they hold together.

Check the food packaging rules of your market

Rules for packaging that touches food, and for what must be printed on a sack, differ from country to country. Before ordering, check the rules of the country where the food will be sold, and ask the supplier for what those rules require.

Al-Sharq supplies customers in Egypt, other African countries and the Middle East. To ask what it can make for your product, use the enquiry form.