Why products break in transit, and the fix for each cause

A customer sends you a photo. The glass jar is in pieces, but the box looks almost new. Was it the courier, or was it the packing?

Most sellers answer that question with a guess. I would rather you answer it with the evidence, because the box and the product usually tell you what happened.

We make cushioning in Jaipur, and we also ship our own goods to buyers in 20+ countries. So I look at this question from both sides of the box.

Products break in transit for five reasons. They get dropped. They get crushed under other parcels. They get shaken for hours on a truck. Something sharp goes through the box. Or they move around inside their own box and hit the wall, or each other. Each cause leaves different marks, and each one needs a different fix. Adding more bubble wrap helps with some of them and does nothing for the others.

This list is not my invention. Test labs think about transit in the same way. ISTA's overview of its parcel test, ISTA 3A (2018 version), puts a packed box through drops, then vibration with and without a load stacked on top, then more drops, including one onto a hard block. ASTM D4169 (version D4169-23e1) also builds its test plans from a sequence of the hazards a shipment is expected to meet on its route.

The five causes at a glance

Let us take them one at a time.

1. Drops and impacts

A parcel is picked up and put down many times between your dock and the customer's door. Every time a hand slips, or a box slides off a belt or a stack, it falls.

The US Department of Defense handbook on cushioning design, MIL-HDBK-304C (1 June 1997), sums up the handling studies of its time in a few plain lines. Most packages get many drops from low heights, and few get more than one from a great height. In most of those studies, more than half of all drops landed on the bottom of the package. So the base of your pack takes the most hits. Corners and edges still get hit, and a corner drop puts the whole force on a very small area.

What it looks like:

1. One crushed corner or edge on the box, and the product broken on that same side.
2. Cracks in glass or ceramic that spread out from one point.
3. A cushion that is flattened where the product pressed into it, with the product touching the box wall.

The third one has a name. Packaging engineers call it "bottoming out": the cushion squashes completely, and almost the whole shock passes into the product. It happens when the cushion is too thin or too soft for the weight it carries.

The fix is cushioning between the product and every wall of the box, corners included, thick enough that the product cannot push through it. If I could add protection in only one place, I would put it under the product, because the base takes the most drops. For very fragile items, pack the product in a small box with cushioning, then cushion that box inside a bigger one.

I would not trust a "Fragile" sticker to do any of this. The same handbook says that fragile and handle-with-care labels have some effect, but a minor one.

2. Crushing under other parcels

In a truck or at a hub, parcels are stacked. The box at the bottom carries everything above it, sometimes for many hours. If the box is weak, or half empty, its top sinks and the product takes the load.

The signs in the photos:

1. The top of the box dished in, or the sides bulging out.
2. Creases running across the side panels.
3. Tins, cartons and soft packs dented or flattened from above, even with good cushioning around them.
4. Several parcels from the same dispatch with the same marks.

Humidity makes this worse. Corrugated board takes up moisture from the air and loses strength as it does. A technical note from Georgia Tech's Renewable Bioproducts Institute (Roman Popil, April 2018, updated May 2019) estimates that box compression strength changes by about 10% for every 10-point change in relative humidity. It also cites the Fibre Box Association's figure of about a 32% loss at 80% relative humidity. This is why crushing complaints tend to rise in the monsoon.

Most of a box's stacking strength sits in its corners and in the flutes that stand upright, as NC State Extension's guide to produce packaging explains. A box with a crushed or wet corner has lost much of its strength before the next parcel is even stacked on it.

The fix:

1. Use a box with enough stacking strength for the weight and the route. Ask your box supplier for the box compression strength (BCT), measured by a method such as ASTM D642, and do not stop at the number of plies.
2. Fill the box. In a full box, the product and the filling help hold the top up. A half-empty box caves in.
3. Store empty cartons off the floor in a dry place, and use the oldest stock first.
4. When you load your own vehicle, put the heaviest parcels at the bottom.

Honestly, I would rather pay a little more for a stronger box than keep paying for replacements.

3. Vibration

Vibration does its damage slowly. Think of a tiffin box in a bag on a long bus ride. Nothing falls and nothing is crushed, and still the dal finds its way past the lid by the time you arrive.

A parcel on a truck gets the same treatment for hours, sometimes days. Caps work loose. Screws back out. Two bottles rub against each other until the print is gone. This is why the vibration tests in ASTM D999 (D999-08, reapproved 2023) judge the box together with its inner packing and its closures, not the box alone.

How it shows up:

1. Scuff marks, rubbed print or worn labels where two items touched.
2. Loose caps and slow leaks, with no crack anywhere.
3. Loose screws, rattling parts, or an electronic item that looks fine but does not work.
4. Powders that have settled, so the pack looks half empty.

The answer is to stop things moving against each other. Wrap or separate items that touch. Tighten caps and seal them with tape or a shrink band. Fill the gaps so the product cannot slide. Keep glossy or printed surfaces away from rough material that can scratch them.

4. Puncture

A puncture comes from a point: a forklift tine, the corner of a heavier parcel, a sharp edge on a cage or a conveyor. It can also come from inside, when a hard corner of the product presses on the box wall and the box gets knocked from outside.

What you will see:

1. A hole or a tear in the box, with damage on the product at the same spot.
2. The edges of the hole pushed inward, which means something came in from outside.
3. The edges pushed outward, which means the product's own corner went through.

The fix is stronger board, or a double-wall box, for heavy and high-value parcels. Keep the product's hard corners away from the box walls with cushioning or corner pieces.

We make air cushion film, and here is its honest limit. A sharp point bursts an air pillow, and bubble film too. Air is good at cushioning and filling space. It is poor at stopping a point. I would rather tell you that here than have you find it out from a returned parcel.

5. Movement inside the box

This one confuses sellers the most, because the box arrives looking fine. It is also the one I would fix first, because it is usually the cheapest to fix. The product was moving inside it the whole way. Every knock outside turned into a hit inside, as the product slid across the empty space and struck the wall, or another item in the same order.

The evidence usually looks like this:

1. A clean box with a broken product.
2. Cushioning that has slid to one side or settled at the bottom.
3. Two items from the same order damaged where they touched each other.
4. A customer who says the box rattled when they picked it up.

The fix is a box that fits the product, with room for cushioning on every side, and not whichever box happened to be on top of the pile. Fill the empty space so nothing moves, and keep items in a multi-item order apart. Then close the box and shake it. If you hear anything move, it is not ready.

Reading the evidence

I always start with the box, not the product. Ask the customer for photos in this order: the outer box from all sides, then the product and the cushioning as they found them. Once the cushioning is pulled out and thrown away, half the story goes with it.

Then use this table:

One broken order tells you little. The pattern over many orders tells you a lot. Our guide to tracking your damage rate shows how to log each case so that the pattern shows up.

When it is not transit damage at all

Before you change the pack, rule out three things:

1. The product was damaged before it was packed, which is a manufacturing or handling problem in your own warehouse. Open one unit from the same batch in your stock and check it.
2. Heat. A parcel in a closed van in May gets hot. Wax, chocolate and some adhesives soften, and more cushioning will not stop that.
3. Air freight. Lower air pressure at altitude can push liquid past a cap that was not tight. ISTA's 3A test has an optional vibration step under low pressure for parcels that may travel by air.

Then test the fix

Once you know the cause, change one thing and test it before you change the whole line. A simple drop test in your own warehouse checks the fix for drops and loose products. For picking the material itself, see choosing cushioning by product weight and fragility.

At Jagannath Polymers, cushioning is one of our product lines: air cushion systems and paper wraps. So yes, we have an interest in selling you more of it. But cushioning is the main fix for only two of these five causes, drops and movement inside the box. Crushing needs a better box. Puncture needs stronger board. Vibration needs things held apart and closures sealed properly.

If you are not sure which cause you are looking at, send us two photos, the outer box and the product as found, and tell us the route. We will tell you which of the five it looks like.