Steady-state gas permeation through a laminate behaves like electrical resistors in series: each layer of thickness L and oxygen permeability P contributes a diffusion resistance R = L / P. The stack's total resistance is the sum of the layers', and its oxygen transmission rate (OTR) is the reciprocal:
R_total = Σ (L_i / P_i)
OTR = k / R_total (lower OTR = better barrier)
The top panel draws the stack as a real cross-section (thickness to scale); the bottom panel draws the same stack as a resistor ladder, with each layer's bar width proportional to its share of R_total — the layer that dominates the ladder is the one actually controlling the barrier, regardless of how thick it looks in the cross-section.
Shelf life is estimated from a fixed oxygen-sensitivity budget divided by OTR — a tighter barrier buys more days before the packaged product oxidises past its threshold.
Recyclability score follows real mono-material design guidance (used by the EU PPWR and most national extended-producer-responsibility schemes, and reported on an Environmental Product Declaration): a single polymer family sorts and reprocesses cleanly near 100%. Every additional distinct material class in the stack makes mechanical separation impractical for standard material-recovery facilities, so the score drops sharply per extra material — and any aluminium-foil or metallised layer is treated as effectively unrecyclable in a standard stream, collapsing the score toward zero regardless of how thin it is.
- Add / remove layer — build up a laminate the way real barrier films are engineered (e.g. PE / EVOH / PE for an oxygen-barrier pouch, or PET / Al foil / PE for a retort pack).
- Drag a layer row — reorders the stack (lamination order doesn't change total resistance in the steady-state model, but it changes which face meets the product — try it and watch OTR hold steady while the cross-section flips).
- Material dropdown — sets the selected layer's polymer or metal and its real-world oxygen permeability coefficient.
- Thickness slider — thicker layers resist diffusion better (lower OTR) but add material and cost. You can also drag a layer boundary directly in the cross-section panel.
- Reset to mono-material — collapses the stack to a single PE layer, the recyclability ceiling every laminate trades away for barrier performance.
Real-world relevance: this is exactly the trade-off packaging engineers face when choosing between a fully recyclable mono-material pouch and a higher-barrier multilayer laminate that extends shelf life but is rejected at most recycling sorting lines.