Leno Mesh Bags: Types, Sizes and Uses

What a leno weave is, how leno, raschel and open-weave produce bags differ, and how to size and specify a mesh bag for onions, potatoes and citrus.

Onions, potatoes, garlic and citrus are alive after harvest. They breathe, give off heat and moisture, and rot when that moisture has nowhere to go. A closed sack that suits rice or cement will spoil a load of onions in days. The mesh bag exists for this one job: hold the weight, let air through, and let a buyer see what is inside without opening it. Leno is the weave that makes an open mesh strong enough to carry 25 or 50 kg, and it is the name most growers and traders use for the bag itself.

What a leno weave is

In a plain weave, tapes cross over and under each other and stay in place only because they are packed close together. Space them out to make a mesh and they slide, the holes close up on one side and open on the other, and the fabric loses its shape. A leno weave fixes that. The warp tapes run in pairs, and each pair twists around every weft tape it crosses. The twist grips the weft like a knot, so the openings keep their size and position even when the bag is dragged or stretched. The result is a light, open fabric that does not ladder or gape.

Three kinds of produce bag

The three are often sold under one name, so it pays to say which is wanted. Our ventilated PP woven bag is made in open weave and in leno mesh from virgin polypropylene at 60-80 GSM, with 5 to 15 percent open area, for fills of 10, 25 and 50 kg. We do not knit raschel nets; the column above is there so a buyer can tell the products apart when comparing quotes.

Why ventilation decides shelf life

Stored bulbs and tubers keep respiring. In a stack, the heat and water vapour they release have to leave through the bags, and where they cannot, condensation forms on the cooler outer layer. Wet skins are where neck rot and soft rot start in onions and where potatoes begin to sprout and green. An open mesh lets store ventilation or a passing breeze carry the moisture away from the middle of the stack. It also lets the produce dry after rain or washing, and it lets heat escape from a load that was bagged warm from the field.

Sizing the bag

Size follows fill weight and the bulk of the crop. Onions take more room per kilogram than potatoes, and large-grade produce packs more loosely than small. The bag should close with a hand's width of fabric to spare; an overfilled mesh bag puts the whole load on the closure and splits there. Our stock dimensions are 40 x 60 cm and 50 x 80 cm, with other sizes made to order. Confirm any size with a trial fill of the actual crop and grade before placing a volume order, because a bag that suits one variety can be short for another.

Colour, closure and label

Colour

Chosen to flatter the crop: red and violet for onions, yellow and orange for potatoes and citrus, green for cabbage. Our standard colours are natural, green, red and yellow.

Closure

Drawstring woven into the mouth for fast closing by hand; sewn or heat-sealed mouths for packing lines.

Label

An open mesh cannot carry print. Branding goes on a woven-in band, a stitched tag or a card under the drawstring.

Mesh opening

Small enough that the smallest grade cannot push through, large enough for air and for a view of the produce.

Reuse

A leno bag survives several trips. Wash and dry it between crops to avoid carrying disease from one lot to the next.

Sunlight is the usual cause of failure

Produce is graded, weighed and often stored in the open, and a mesh has thin tapes with no shade from neighbouring tapes. An unstabilized bag can weaken in a few weeks of strong sun and then tear when it is lifted full. Order mesh bags UV stabilized, and say how long and where they will be outdoors. The stabilizer is the same HALS system used in our UV stabilized PP woven fabric. Our guide to UV stabilization explains how to put that into an order as a figure a supplier can test rather than a single word.

When a mesh bag is the wrong choice

Ventilation is a requirement of living produce, and a fault for anything that must stay dry. Milled and processed goods need the opposite construction: a closed weave, usually coated. Rice belongs in a printed PP woven rice bag, sugar in a PP laminated sugar bag and compound feed in a PP laminated animal feed bag, all of which keep humid air out. Dry pulses and whole grain sit in between and travel in plain woven sacks made from the standard PP woven fabric roll, which breathes a little without leaving the product exposed. A trader handling both fresh and dry lines usually needs both kinds of bag.

What to send with an enquiry

A quote for mesh bags depends on seven facts: the crop and its grade, fill weight, bag width and length, colour, closure type, whether a label band is needed, and the months of outdoor exposure. Add the quantity and the port or city of delivery. With those in the first message, a sample can be made to match rather than guessed at. Enquiries go through the contact page, and the minimum order for ventilated bags is 50,000 pieces.