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Types of Containerboard – What You Should Know About Liners and Flutings

Corrugated board is one of the most widely used and most sustainable packaging materials. The strength of a box, how much load it can withstand, and how it looks when printed all depend primarily on the paper grades used in its production. These materials fall into two main categories: liners (the outer and inner flat layers) and flutings (the corrugated medium between them).

This article provides a clear and concise overview of the most common paper types and when each is the right choice.

 

What is the difference between liners and fluting?

  • Liners form the smooth outer and inner surfaces of the board. They determine the appearance and partially the strength of the packaging.
  • Fluting is the corrugated medium between the two liners. It acts like a “paper spring”: it absorbs shocks and provides rigidity to the board.

Both components must meet different optical and strength requirements based on their function.

Liners (Cover Papers)

Colours and appearance

The most common liner colour combinations are:

  • Brown–brown: natural brown on both sides
  • White–brown: white exterior, brown interior
  • White–white: white on both sides, offering a premium, aesthetic appearance

How is a liner made white?

There are two main methods:

1. Bleached White Kraftliner

Made from bleached fibres — a strong, printable paper produced from virgin pulp.
In two-layer white kraftliners, the top layer consists of bleached hardwood kraft fibres. The bleaching process is carried out under completely chlorine-free (TCF) conditions.
The base layer is a blend of softwood fibres and a small amount of high-quality recycled fibres sourced from corrugated board.
White testliner is also available in different quality grades.

2. Coated White Testliner (milled/coated white recycled liner)

A premium recycled-based paper with a coated surface that provides excellent printability and high visual quality.
This is also a two-layer construction: beneath the coating there is a layer of white recycled fibres, and the base layer consists of brown recycled fibres.
Coated white kraftliner is also available on the market.

Advantages and limitations

  • White or coated liners:
    ✔ Excellent printability
    ✔ Aesthetic, high-quality appearance
    ✔ Suitable for branding and premium packaging
    ✘ Higher price point
  • Brown liners:
    ✔ Sustainable and cost-efficient
    ✔ Naturally appealing look
    ✘ Limited print performance

Types of liners by strength

Kraftliner

  • Contains virgin fibres → very high strength and moisture resistance
  • Ideal for export packaging, industrial use, heavy loads, and cold-chain packaging

Testliner

  • Made from 100% selected, high-quality recycled fibre
  • Excellent price–performance ratio
  • Suitable for standard packaging applications

Schrenz / Srenc

  • 100% recycled paper made from unselected, lower-quality recovered fibre
  • Typically grey or grey-brown due to its mixed fibre content
  • Uncoated, rough surface
  • Commonly used as an inner liner or for low-performance applications

Fluting (Corrugated Medium)

Fluting provides the backbone of the board: mechanical strength, rigidity, and impact resistance. Just like liners, it can be produced from virgin or recycled fibres.

Main types

SC-Fluting (Semi-Chemical Fluting)

  • Made from virgin fibres
  • High tensile strength and good moisture resistance
  • Recommended for export packaging and heavy-duty applications

Recycled Fluting / Wellenstoff

  • Made from 100% recycled fibres
  • Sustainable and cost-effective
  • Ideal for standard packaging needs
    “Wellenstoff” is a German term commonly used for recycled corrugating medium.

Which paper type should you choose?

Virgin fibre-based grades (kraftliner, SC-fluting)

✔ High strength
✔ Good moisture resistance
✔ Suitable for overseas export, heavy industrial goods, and sensitive products

Recycled grades (testliner, srenc, wellenstoff)

✔ Sustainable
✔ Economical
✔ Ideal for general packaging applications and normal load requirements

Domestic production – sustainable solutions from Hungary

In Hungary, containerboard is produced exclusively by Hamburger Hungária Kft., the Dunaújváros paper mill of the Austrian family-owned Prinzhorn Group.
Their “Austro” branded products are exported at a rate of around 80%.

Their portfolio consists entirely of recycled-based grades, including:

  • AustroLiner 2 and AustroLiner 3 liner papers
  • AustroFluting Plus, AustroFluting-R, AustroWelle, and AustroWelle Light corrugating mediums
    Available in a grammage range of 80–175 g/m².

Why does choosing the right paper matter?

The liner–fluting combination determines:

  • the mechanical strength of the packaging
  • printability and visual quality
  • packaging costs
  • environmental performance

Kraft-based solutions are ideal for premium and heavy-duty applications, while recycled papers offer a sustainable and cost-effective alternative for the majority of packaging needs.

You can explore the product portfolio of Hamburger Containerboard here: Products - Hamburger Containerboard


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