PP woven bags: how they are made and how to order

A PP woven bag is a sack made from fabric woven out of flat polypropylene (PP) tapes, cut to length and sewn shut at the bottom. It is the usual packaging for dry goods sold by the sack, such as flour, sugar, rice, animal feed, fertiliser and seeds, commonly in fills of 25 kg or 50 kg.

The fabric is strong for its weight, resists tearing and stacks well. It leaves the loom as a tube, so an ordinary bag has no side seams and only the bottom is sewn. Plain woven fabric is not watertight: air and moisture pass between the tapes, and a very fine powder can sift through.

Key definitions

• Tape. The flat strip of polypropylene that the fabric is woven from, slit from an extruded film and stretched for strength.
• Warp and weft. The two directions of the weave: warp tapes run the length of the bag, weft tapes run round it.
• Circular loom. The machine that weaves tapes into a seamless tube of fabric.
• Fabric weight (GSM). Grams per square metre of fabric. A higher figure means more polypropylene and a stronger, heavier bag. For ordinary sacks it commonly falls between about 50 and 120 GSM.
• Denier. The weight in grams of 9,000 metres of tape. The higher the denier, the heavier the tape.
• Mesh. The number of tapes per inch of fabric in warp and weft, for example 10 × 10. Denier and mesh together decide the fabric weight.
• Hemmed top. The mouth of the bag is folded over and sewn, which gives a firm edge that does not fray.
• Heat-cut top. The mouth is cut with a hot blade that fuses the ends of the tapes so that they do not unravel, with no fold and no stitching.
• Stitched bottom. The bottom of the tube is folded and sewn shut, with a single or a double fold and row of stitching.

How a PP woven bag is made

Production follows five steps, in this order. The factory page of Al-Sharq Plastic Manufacturing Company shows them with photos from its own production floor.

1. Tape extrusion. Polypropylene granules are melted and extruded as a thin film, which is slit into narrow tapes. Drawn over a series of rollers, the tapes stretch and gain their tensile strength.
2. Winding. Each tape is wound onto its own bobbin, ready for the looms.
3. Circular weaving. Shuttles carry the weft tapes round the ring of a circular loom while the warp tapes feed in from the creel, producing a seamless tube of fabric. The flat width of that tube is the width of the bag.
4. Fabric on the roll. The tube is flattened and taken up on rolls. Coloured tapes on the creel give a coloured fabric or coloured stripes, so the colour is woven in, not printed on.
5. Cutting, sewing and printing. The fabric is cut to the length of the bag, and the bottom is folded and sewn. Bags ordered with print carry the customer’s design.

White or coloured, printed or unprinted

Colour and print are separate choices, so the Al-Sharq range fits in one small table.

Fabric	Unprinted	Printed
White	Plain white bag for general packing	White bag carrying your brand and product details
Coloured	Coloured or striped bag that identifies a product at a glance	Coloured or striped bag carrying your print

Each option has its own page: white, coloured, printed and unprinted bags.

How to describe the bag you need

A supplier can only quote for the bag you describe. Start from the contents: a light product such as bran needs a larger bag than the same weight of a dense one such as sugar. Then settle three points:

1. How the bag will be treated. Filling, closing, stacking height, transport and outdoor storage decide the fabric weight. State the GSM of your present bag if you know it; if not, describe the use and ask the supplier to propose a fabric.
2. The top and the bottom. Say whether you want a hemmed or a heat-cut top, and ask whether the bottom is single or double folded and stitched.
3. Options. Inner liners, lamination and UV stabilisation exist in the trade, for fine powders, goods that must stay dry and bags that stand in sunlight. Not every maker offers each of them.

When in doubt, offer to send a sample of the bag you use now.

What to send for a quotation

Bags are made to order, so a quotation starts from your requirements. Six details are enough:

1. Size. Width and length of the flat bag, in centimetres.
2. Contents and weight. What the bag will hold, and how many kilograms per bag.
3. Fabric colour. White, a colour, or white with coloured stripes.
4. Print. Unprinted or printed. For a printed bag, send the artwork, say where on the bag it should appear, and check the labelling rules of the country where the goods will be sold.
5. Quantity. The number of bags in this order, and whether the order will repeat.
6. Destination. City and country of delivery, or the port for an export order.

Send them through the enquiry form; the same list is on the products page. Ask in the same message for the price, the minimum quantity, the lead time and the delivery terms.

Where Al-Sharq fits

Al-Sharq Plastic Manufacturing makes polypropylene woven bags, white and coloured, printed and unprinted, to the buyer’s requirements at its plant at Plot 176, Southern Developers Area, 10th of Ramadan City, Sharqia Governorate, Egypt, and supplies customers in Egypt, in other African countries and in the Middle East. The photos on this site show a tape extrusion and stretching line, winders, circular looms, white, red and striped fabric, and plain sewn bags.

The figures and options in this guide are general trade knowledge, not a statement of what Al-Sharq makes. For your own order, send an enquiry with the six details above.