Two absorbent pads can look identical, carry the same absorbency figure and sit in the same tray, and still be different products — because the core decides what the pad can be called and which disposal route has to exist for that claim to mean anything. The pad under a beef steak and the pad under a punnet of blueberries are not the same specification, and the difference is not the size. This article maps tray scenarios to the core and the grade that fits.
Why the core decides the grade
A pad is a core wrapped in a food-contact top sheet and a barrier back sheet. The absorbency comes from the core, and the core is the layer that decides the compostability claim:
- Starch-based and cellulose cores are the routes that carry a compostability claim today.
- SAP-based cores absorb more per gram, but the superabsorbent polymer is not compostable, and no top sheet changes that.
- Back sheets and top sheets matter too. A compostable core under a polyethylene back sheet still leaves a pack that will not compost as one piece.
The practical consequence: ask what the core is, not just what the pad absorbs.
Two grades, and why the market decides which one matters
Compostability grades are tied to a disposal condition. Industrial composting (EN 13432, ASTM D6400) runs hot and fast and takes a wider range of material. Home composting (TÜV OK compost HOME) runs cooler and is a harder test to pass. A pad certified for the industrial route will not break down usefully in a garden heap, and a home-certified pad is not automatically the right answer either — in most of Asia and much of North America the collection infrastructure is industrial, landfill, or absent.
That is the part buyers skip. A compostable pad sold into a market with no composting collection produces no environmental result; it produces a cost. The grade should be chosen against the collection that actually exists where the tray is sold — not against the strongest certificate available. If the end market only has landfill, the honest position is that the pad's compostability is a procurement choice rather than an environmental one.
By tray: what to specify
The core question is not "which pad", but "what does this tray do to a pad, and which core survives it while still meeting the grade".
| Tray | Absorbency demand | Core to specify | Grade that fits | Most-missed point |
|---|---|---|---|---|
| Red meat | High, and fast — purge comes out early | Starch-based or cellulose, higher gsm | Industrial; home where a grade exists | Back-sheet barrier: purge wicks through if it is too thin |
| Poultry | High, with a wetter drip | Cellulose core, denser structure | Industrial | Wet strength — a light core tears when the tray is lifted |
| Seafood | High, plus free liquid | Cellulose or starch-based, with a firm back sheet | Industrial | Free liquid pooling: capacity is not the same as drainage |
| Leafy vegetables | Low to moderate; condensation rather than purge | Light cellulose core | Home or industrial | Over-absorbing — a heavy core dries the leaf edge |
| Berries | Low, but the pack must not crush | Thin cellulose core | Home or industrial | Thickness: a thick pad lifts the fruit and the lid does not close |
| Cooked and prepared food | Moderate, and the pad is often seen | Cellulose core, clean edge | Industrial | Appearance and bleed-through once the pack is on display |
What the pad still has to do
The compostability claim is an addition to the pad's job, not a substitute for it. Whichever core is chosen, the pad still has to hold liquid in, resist rewet under the weight of the product, sit flat so the tray closes, and be food-contact compliant for the product type it touches. A compostable pad that rewets under a loaded tray has not done its job, and a lighter core will pass a bench absorbency test and still fail in a full tray — so test at the real load.
Common misuse
- Specifying by absorbency alone. Capacity says nothing about the core, and the core carries the claim.
- Changing the core but keeping a polyethylene back sheet. The pack then composts in no condition, and the certificate on the core does not transfer to the finished pad.
- Ordering a home-compost grade into an industrial-only market — or the reverse, where the customer's audit expects the industrial standard.
FAQ
Are all absorbent pads compostable?
No. Most pads are built on a superabsorbent polymer core, which is not compostable, and the top and back sheets are usually not either. A compostable pad is a specific construction, not a category.
Does a compostable pad absorb less?
Not necessarily less, but differently. Compostable cores are generally bulkier for the same capacity, which changes the pad thickness and how it fits the tray. Select on tissue thickness as well as the capacity figure.
Which grade should we ask for?
Whichever condition exists where the pack is sold. Ask the customer where the tray is discarded and request the certificate for that condition — EN 13432 or ASTM D6400 for industrial, OK compost HOME where home composting is real.
Browse the range
For the compostable construction itself, start at biodegradable absorbent pads. For specifying a single grade in detail, see how to specify a biodegradable absorbent pad, and for the wider category see fresh absorbent pads.