Packaging data sheets use a small vocabulary repeatedly, and several of the terms mean something narrower than they appear to. Misreading them is how people end up with the wrong specification twice. Six worth knowing.
Grammage / GSM
Weight per square metre. It tells you what the material weighs and very little about how it behaves – two materials at identical grammage can differ substantially in stiffness. It is useful for costing freight and for spotting when a supplier has changed something. Not useful as a performance specification. We went through this in detail for sheet in what GSM means on a corrugated sheet spec sheet.
Compressive strength
Resistance to being crushed through the thickness. Useful if the material is being crushed. Useless if it is being bent – and most panels and sheets are being bent. If a quote leads with this figure and the application is a layer pad, ask for a flexural number.
Flexural modulus / flexural strength
How the material behaves in bending. This is the number that matters for anything spanning a gap. Modulus is stiffness – how much it deflects under load. Strength is where it breaks. For a packaging application, modulus is usually the one you care about, because it fails by deflecting long before it fails by breaking.
Virgin, recycled, regrind
Virgin is new resin. Recycled is material that has been through a use and a collection. Regrind is manufacturing waste reprocessed – technically recycled, but post-industrial rather than post-consumer. The distinction matters the moment anyone asks you for a recycled content claim, which we covered in recycled content claims.
UV stabilised
An additive package that slows ultraviolet degradation. Without it, polypropylene chalks and embrittles in sunlight. Worth having outdoors, worth not paying for indoors. Ask whether it is included rather than assuming.
Tolerance
The allowed variation on a dimension. Frequently omitted, and it is the one that causes arguments at goods-in. A sheet quoted at four millimetres with no tolerance can arrive at 3.6 and there is no basis for the conversation. Ask for it on thickness and on cut dimensions.
And one that is not on the sheet
Trip life. No data sheet will tell you how many trips something will make in your operation, because it depends on your handling. Any supplier quoting a trip-life number without asking about your loop is guessing, and it is worth treating the number accordingly.
How to compare two quotes properly
Put the numbers side by side in the same units and check which ones differ. If one quote has a flexural figure and the other only has compressive strength, you are not comparing the same property, and the cheaper one may simply be the one that disclosed less.
Then check thickness with a caliper on samples. It takes seconds and it settles most of these comparisons immediately – a sheet or panel that is under its stated thickness is the single most common discrepancy.
Any supplier who will answer all of this is comparable. Any supplier who will not is asking to be compared on price alone.
What we can do
We supply PP honeycomb panels and quote with the terms above stated explicitly rather than leaving them to be inferred. Tell us what you are comparing, and we will give you the numbers that actually distinguish one option from another – including telling you which numbers do not matter for your application.