The paper on the outside of the box is known – not surprisingly – as the outer liner. It will normally be made out of virgin kraft paper, although, despite the name, these days it will actually contain up to about 12% recycled material.
It follows naturally that the paper on the inside of the box is known as the inner liner, and this will usually be made out of fully recycled materials, a mixture of newspaper waste, virgin board, and so on; it’s not as rigid as virgin kraft, and it doesn’t look quite as good, but that doesn’t matter because the real strength – and good looks - is needed on the outside. It also reduces the overall weight of the board and, of course, being fully recycled makes it better for the environment. It is known as Test 3 and is represented in our box specification by the letter T.
Double wall cardboard boxes will have another sheet of liner paper between the flutes. This may also be Test quality paper, although Chip liner is also often used.