Your onion bag didn't fail. Your onions sweated.

A packer calls and says the bags failed. Half a pallet came back soft, the buyer rejected it, and the bag is the obvious suspect because it is the thing you can hold in your hand.

Almost every time, the bag did not fail. The onions sweated, and the pack had nowhere to put the moisture.

Where it actually starts

An onion keeps living after you pack it. It respires, and respiration gives off heat and water vapour for days. That moisture has to leave the pack or it condenses on the first cold surface it finds — which, inside a stacked pallet, is the bulb next to it.

It collects at the neck first. The neck is where the leaves were cut, it is the least protected part of the bulb, and it is the part that stays wet longest. Wet neck, warm pallet, no airflow: that is the whole recipe, and it does not need a single hole in the bag.

By the time it shows, the rot is in the middle of the stack. The outside bags look fine. That is why the diagnosis usually lands on the wrong thing.

Why the middle of the pallet

Air moves around the outside of a pallet and not through it. The bags on the faces get airflow whether the pack ventilates or not. The ones in the core only get the air the packaging lets through.

So a pack that ventilates marginally will look acceptable for a long time — every outside bag is fine — and then fail all at once in the core of a full load on a long haul. The failure is not random. It is the bags that were least able to breathe, in the position where breathing mattered most.

What this rules out

A few things people change first, that usually are not the cause:

Bag strength. If the bag tore, it tore because someone lifted a soft, heavy pallet, not because the material was under-spec. Soft product came first.

Bag size. An onion pack that is too tight restricts airflow, so size can be part of it — but going up a size without changing ventilation just gives you a bigger pack with the same problem.

The closure. A clip, a stitch and a heat seal all breathe about the same, which is to say not at all. The closure is worth changing for other reasons — several US chains now refuse metal staples in the pack — but it will not fix sweating.

What actually changes it

Ventilation, and how much print area you are willing to give up to get it.

All mesh breathes best. Air on every side, nothing blocking it. It also barely prints, which is the trade-off: this is a working bag, not a shelf bag. If the pack is going to a repacker or into food service, this is usually the right answer and the cheapest one.

Combo puts a printed film face on one side and a mesh window on the other. Less airflow than full mesh, enough for most retail onion programs, and you get the panel the chain wants. This is where most branded onion programs end up.

Tube bags off the roll ventilate like mesh and take the operator out of the bottleneck, because the machine cuts and closes instead of someone feeding bags. If the constraint is the shift rather than the shelf, look here.

Perforated poly is the one to be careful with. It prints beautifully and it does not move nearly enough air for onion in volume. It works for produce that tolerates moisture. Onion does not.

The question worth asking first

Before changing anything, find out where in the pallet the failures were. If they were in the core and the outside bags were sound, it is ventilation, and no amount of extra gauge will fix it. If failures were random across the load, something else is going on — field heat, harvest moisture, or a cold chain that broke — and the packaging is genuinely not the problem.

That one question saves a season of changing bags for the wrong reason.