Duplex board is really two products in one sheet. The top has to be bright, smooth and coated well enough for multi-colour printing, while the back – usually made from recycled fibre – has to give the board its stiffness at a sensible cost.
For the top side, our duplex customers use coating clay or premium clays such as Kaolite-90 and KCC Fines, with titanium dioxide where they need extra opacity. Binding comes from oxidised starch and PIDICRYL 128-M, and optical whitening agents lift the visual whiteness of the top.
Common duplex challenges
- Dusting and calender build-up – SAPCOTE C-104 lubricant gives a smoother, cleaner coating.
- Coating colour viscosity – PIDICRYL 6250 keeps high-solids colour flowing.
- Stiffness in the back layers – D.S.R. and cationic starch.
- Stickies from waste paper – stickies control and deinking chemicals where the top liner uses recycled fibre.
- Grey back shade – pigment dyes and Direct Black for a uniform back colour.
Because we supply coating, wet-end and machine clothing items, a duplex mill can consolidate a large part of its purchasing with us and deal with one team.