Oven Kraft trays are made from two corrugated boards: G-Flute at 0.8 mm and F-Flute at 1.2 mm. They are built the same way and perform across the same temperature range. The choice between them comes down to one question: how much wall does the format need?
What the two boards share
Both boards use the same five layers: a functional barrier film of 8–10 µm on the food-contact side for barrier grades, a food-grade kraft liner, a starch-based adhesive, the corrugated core and an outer kraft liner. Both are rated for service from −28 to +220 °C, come in kraft, dark kraft, black and white finishes, and are made from FDA-compliant food-contact materials.
The only difference is the corrugated core.
Why the core matters
Corrugated board is stiff because of its shape. The fluted core works like a row of small beams between the two liners. A taller flute moves the liners further apart, which makes the board stiffer in bending.
A finer, lower flute gives a flatter surface, sharper folds and less material per tray. That is why G-Flute, at 0.8 mm, suits most baking trays and cake bases, and F-Flute, at 1.2 mm, takes over where the tray has more to carry.
Four questions that decide the board
| Question | Usually G-Flute | Usually F-Flute |
|---|---|---|
| How large is the format? | Standard trays, loaf pans and cake bases | Long or wide trays and forms |
| How demanding is the geometry? | Shallow to medium walls | Deep or tall walls, shapes that must hold form under load |
| How heavy is the fill? | Typical bakery and produce fills | Higher fill weights |
| How is it handled? | Standard depositing, freezing and display | Heavier handling and stacking loads |
Examples from the catalogue
- Baking trays, such as the W4430 and W5262, run in G-Flute.
- Deep baking trays, such as the W2106 and W2685, are made in F-Flute.
- Produce trays appear in both boards, depending on size and fill.
Every product page lists its board, and the catalogue can be filtered by board.
When it is not obvious
Some formats sit between the two. In those cases the decision is made during a specification session with our team and confirmed on your line. A short trial of both boards with your real fill and oven profile usually settles it.
Read more
The G-Flute technology and F-Flute technology pages explain each board in detail. For new or unusual formats, see Custom formats.
