Ask most people which insert protects a vial better and they will say foam. They are right, and it is frequently the wrong answer anyway, because “better” is not the same as “necessary”.
How each one actually holds a vial
The two materials work on completely different principles, and understanding that makes the choice obvious in most cases.
EVA foam is a closed-cell material that compresses and springs back. The cavity is cut fractionally smaller than the vial, so inserting it compresses the cavity wall and the wall pushes back. That interference fit is what holds the vial, and the same compressibility is what absorbs energy in a drop.
Paperboard does not compress meaningfully. A folded platform holds a vial through geometry: a punched hole sized fractionally larger than the vial, with small relief tabs around the perimeter that flex against the glass. The vial’s base rests on the box floor, so the deck locates it while the floor carries the weight.
One is a shock absorber. The other is a locator. That distinction settles almost every decision.
The question that decides it
Does the box travel on its own, or inside an outer case?
If it travels inside a case, the case absorbs the impact. The insert only has to stop the vial moving, and a die-cut paperboard platform does that perfectly well at a fraction of the cost.
If it is posted on its own — a direct-to-customer pack, a sample going out in a mailer — the insert is the only impact protection in the system. That is when foam earns its money.
Everything else is a secondary consideration.
Where foam is genuinely worth it
- Posted packs with no outer. Nothing else is absorbing energy.
- Heavy vials. A filled 10ml vial has enough momentum to tear a single-layer paperboard hole.
- Repeated opening. Every removal flexes a paperboard relief tab a little further; after several cycles the grip weakens. Foam tolerates the cycle far better.
- Mixed components. One block can carry a round vial cavity, a syringe channel and an ampoule cradle, each cut to its own item.
- Presentation. A flush black foam surface makes labelled vials read cleanly on opening in a way bare board does not.
Where paperboard is the right answer
- Light vials inside a case. 2ml, 3ml and 5ml formats are well within what a folded deck holds.
- Single-stream recycling. Foam is not paper. If the whole pack must go into one recycling stream, paperboard is the honest specification and foam is not.
- Flat shipping. Cartons and paperboard inserts both ship collapsed. Adding foam partly defeats that advantage.
- High volume. At scale the cost difference is substantial and compounds across every unit.
- Boxes opened once. Repeated removal is what wears a punched hole. A single opening does not.
What each costs
We would rather give you the shape of it than a misleading number, since it varies with size, count and quantity.
Foam typically costs several times a comparable paperboard insert. The gap is widest at low volumes, where foam cutting is relatively labour-intensive and paperboard die-cutting amortises quickly. It narrows at high volumes but never closes.
Set against that, foam removes a component from the pack in some cases — a foam block with a lid pad can replace a platform, a partition and void fill.
Where people over-specify
The commonest pattern we see is a customer who has had a breakage, and responds by upgrading the insert to foam without changing anything else.
Often the breakage was not an insert problem. It was a box that was too big for its contents, so the whole pack could accelerate inside the shipper before hitting something. Reducing void fixes that, and costs less rather than more. Foam in an oversized box just gives the loose pack something soft to arrive with.
If you have had transit damage, the first question is not “what insert” but “how much empty space is there”.
Density: the specification people forget
When foam is the right answer, density matters as much as cavity size, and it is the property most often left unspecified.
Too soft, and a heavy vial gradually settles under load and vibration; the cavity takes a set and stops gripping. Too firm, and every insertion takes force, the cavity mouth tears, and the end user struggles to get the vial out.
We select it against your vial weight and how often the pack is opened, then confirm it on a physical sample. A foam that suits a presentation box opened once would be genuinely irritating on a pack opened weekly.
A middle option worth knowing about
Twin-wall or laminated paperboard sits between the two. Bonding two layers, or folding a partition with double walls, gives noticeably more strength than a single deck while staying entirely in the paper stream.
For a 10ml vial inside an outer case, that is often the right specification — more capable than a single-layer platform, cheaper than foam, and it recycles with the carton.
How to decide in one minute
- Does the box ship on its own? → Foam.
- Is the vial 10ml or heavier? → Foam, or twin-wall paperboard.
- Must the pack recycle in one stream? → Paperboard or moulded pulp.
- Will it be opened repeatedly? → Foam.
- None of the above? → Paperboard, and put the saving into the printing.
Send us the vial and tell us how the pack travels. If paperboard is enough, we will say so.
Further reading
How Custom Inserts Help Reduce Vial Movement
Most vial damage is not caused by one dramatic impact. It is caused by thousands of small movements over hours of vibration.
Common Mistakes to Avoid When Ordering Custom Vial Boxes
Most expensive packaging mistakes are made in the first week of a project, before anything is printed.