Guide

What is duplex board? Duplex, folding boxboard and kraft for printed boxes

Duplex board, also called white lined chipboard (WLC), is a paperboard with a white coated printing surface and a grey back made mostly from recycled fibre. It is the everyday board for printed boxes such as shoe boxes, toys and household goods. Folding boxboard and solid bleached board are made from virgin fibre; they cost more and are the safer choice where food touches the box.

By Eastern Dragon Package Tech PLCLast updated 24 September 2026

Key facts

Duplex (white lined chipboard)	White coated top, grey back of recycled fibre; grade codes GD and GT
Folding boxboard (FBB)	Virgin fibre: mechanical pulp between layers of chemical pulp; grade codes GC and UC
Solid bleached board (SBS)	Bleached virgin chemical pulp all the way through
Paperboard	Paper heavier than about 250 g/m²
Food contact	Recycled board can carry mineral oil residues that may move into food

What is duplex board?

Duplex board, also called white lined chipboard (WLC), is a paperboard made in several layers, mostly from recycled fibre. The top is white and coated, usually with two or three layers of coating, so it prints cleanly; the inside is grey, because of the recycled fibre. It is stiff, folds well and costs less than virgin-fibre board, which is why it is the everyday board for printed product boxes. Board grades are often named with the codes of the German standard DIN 19303: coated duplex with a grey back is GD, triplex (with a white back) is GT, and folding boxboard is GC.

Duplex, folding boxboard or solid bleached board?

The three boards look alike from the printed side. The difference is what they are made of, which shows on the back and in how the box can be used.

Board	Made from	Back	Typical uses
Duplex (WLC, GD)	Mostly recycled fibre	Grey	Shoe boxes, toys, cereals, frozen and chilled food in an inner pack, household goods
Triplex (GT)	Mostly recycled fibre	White	Boxes whose inside is seen
Folding boxboard (FBB, GC)	Virgin fibre: mechanical pulp between chemical pulp	White or cream	Health and beauty, food, confectionery, medicines
Solid bleached board (SBS)	Bleached virgin chemical pulp	White	Premium boxes and food packaging

Can duplex board touch food?

With care. Recycled fibre can carry traces of mineral oil from the printing inks of the paper it was made from, and studies in Switzerland found mineral oil moving from recycled board into dry food such as rice. Where food touches the board directly, as with cakes, pastries, pizza or loose biscuits, use virgin-fibre board such as folding boxboard, solid bleached board or kraft, or pack the food in an inner bag or liner first. For products in their own sealed wrap, duplex board is widely used.

How do you choose the board for a printed box?

Four questions settle most choices.

Will food touch the board? Choose virgin-fibre board, or add an inner bag or liner.
Will anyone see the inside of the box? A white back (triplex or folding boxboard) looks cleaner.
How heavy is the product? Heavier products need stiffer board, or E-flute corrugated.
How premium should it feel? Folding boxboard and solid bleached board print brighter and feel smoother.

Questions

Is duplex board the same as cardboard?

“Cardboard” is an everyday word for any stiff paper material. Duplex is one specific paperboard, with a white printing side and a grey back. Corrugated board is a different material: fluted paper glued between flat liners.

What do GD2 and GC1 mean?

They are board grades from the German standard DIN 19303. GD is coated board with a grey back (duplex); GC is folding boxboard made from virgin fibre, with a white back (GC1) or a cream back (GC2). The number separates variants within each family.

Why is the inside of my box grey?

Because it is duplex board: the grey is the recycled fibre inside. If the inside will be seen, choose triplex or folding boxboard, which have a white back.