Face liner vs back liner: the seven properties that actually differ
Both sides of a gypsum board are paper, but they are not the same paper. Grammage, colour, sizing, tensile balance and porosity are specified independently — here is how.
Buyers often source plasterboard liner as one line item. Mills do not make it that way. The face liner and the back liner are separate grades with separate furnish, separate sizing strategies and separate quality risks, and specifying them together is the most common cause of a mismatched trial reel.
The seven divergent properties
| Property | Face liner | Back liner |
|---|---|---|
| Grammage | 140–170 g/m² | 180–220 g/m² |
| Colour | Ivory / cream top ply | Grey, unbleached |
| Top-side sizing | Heavy — paintability, jointing | Light — functional only |
| Tensile bias | CD-weighted for wrap and edge fold | MD-weighted for web tension |
| Porosity | Controlled, low fibre lift | Open, bond-driven |
| Surface smoothness | Critical (Bendtsen controlled) | Secondary |
| Typical defect risk | Show-through, fibre puff, paint flash | Edge cracking, paper break at scoring |
Why the back liner is heavier
The board is scored on the face and snapped away from it. That puts the back liner in tension at the moment of break and makes it the structural hinge during handling. Under-specifying back liner grammage to save cost is a false economy: breakage on site is attributed to the board, not the paper, and it costs the manufacturer the claim.
Ordering them as one spec: what goes wrong
- A single Cobb limit forces the mill to over-size the back liner, weakening the core bond.
- A single tensile spec produces a face liner too stiff in MD, which cracks on the edge wrap.
- A single brightness target prices the back liner as if it needed a bleached top ply — pure cost with no function.
Specify them as two grades, on two positions, with two COAs. WeePaper quotes face and back separately and can ship them from the same mill run so the pair is dimensionally matched.
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