Testliner vs Kraftliner: Choosing the Right Containerboard

What is liner in corrugated board?

Corrugated board is built from two components: liner, the flat sheets on the outer and inner faces, and fluting (medium), the wavy layer glued between them. The liner carries most of the printing and contributes much of the board's bursting and surface strength. Because the liner is what customers see and handle, its quality directly affects both the look and the durability of the finished box. Testliner and kraftliner are the two main liner types, distinguished primarily by the fibre they are made from.

What is kraftliner?

Kraftliner is produced primarily from virgin kraft pulp, giving it long, strong fibres. This makes it the stronger of the two liners, with higher bursting strength and better performance in humid or demanding conditions. Its surface is clean and uniform, which makes it well suited to high-quality printing and premium packaging. Kraftliner is typically chosen where strength and appearance matter most — for export boxes, heavy products, or branded retail packaging — and it usually carries a higher price because of the virgin fibre content.

What is testliner?

Testliner is made mainly from recycled (recovered) fibre, often in two or more layers. Because it uses recovered paper, it is more economical and has a smaller environmental footprint in terms of fresh fibre use. Modern testliner has improved considerably and performs very well for the majority of standard packaging applications. It is the workhorse liner for everyday corrugated boxes where extreme strength is not required and cost efficiency is a priority.

Key differences at a glance

When deciding between the two, it helps to compare them across the factors that matter most for your packaging:

• Fibre — kraftliner is mostly virgin; testliner is mostly recycled.
• Strength — kraftliner is generally stronger, especially when wet.
• Appearance — kraftliner has a cleaner, more uniform surface for printing.
• Cost — testliner is usually more economical.
• Sustainability — testliner uses recovered fibre; both are recyclable.

How to choose between them

The right choice comes down to your priorities. If you ship heavy or high-value goods, export over long distances, or need premium print quality, kraftliner's extra strength and cleaner surface justify the higher cost. If you are packaging everyday goods, shipping shorter distances, and want to control costs or maximize recycled content, testliner is usually the better fit. Many buyers use a combination — kraftliner on the outer face for print and strength, testliner on the inner face for economy. Discuss your product weight, shipping conditions, and printing needs with your supplier to land on the optimal specification.

Grammage and combined board strength

Liner choice is only part of the equation; the grammage of the liner and the flute profile together determine the strength of the finished board. A heavier liner or a stronger flute increases burst and edge-crush performance. Rather than over-specifying, it is best to define the box's required strength — for example, the weight it must carry and the stacking it must withstand — and let the supplier engineer the right combination of liner type, grammage, and flute. This avoids paying for unnecessary strength while ensuring the box performs in the field.