Kraftliner, testliner – what is the difference?
4min read
28/03/2017
The terms kraftliner and testliner are often used in connection with cartons. These two terms refer to the quality of the cardboard and the quality of the paper. Schrenzpapier also falls into this category. We explain what is meant by these terms and what the differences are between kraftliner and testliner.
Everybody knows that cartons can be made from corrugated board in many different ways – but not what the ominous term “liner” is all about. If you ask independently into the blue, you get the most varied answers: from cruise ships to roller skates to the much talked about large trucks, everything is there. Our kind of liners have already been in use for decades and have proven their worth:
It’s all about corrugated cardboard!
When we talk about liners, we are referring to the liner paper that is needed as a component in the production of cardboard. In order to produce a stable folding carton from corrugated board, you need this liner in addition to the so-called fluting paper: the liner forms a smooth inner or outer cover, while the fluting paper is used for the corrugated layer of the carton. Depending on whether the corrugated board base paper is made from virgin wood fibres or recycled fibres, further subdivisions take place:
(Source: Official Journal of the European Union 2015/1072)
The different cover papers
There are three different types of papers that form the top layers or interlayers of the carton:
Kraft liner
Kraftliner
Kraftliner is paper that consists of at least 80% virgin fibre. This fibre material is characterised by its high strength, because the still fresh, long fibres form a very tear-resistant structure. This makes kraftliner papers particularly stable and durable: A corrugated cardboard box made predominantly of kraftliner is enormously resistant. This is why kraftliner boxes are popular when heavy or valuable freight, hazardous goods or merchandise are to be packed and shipped over a long transport route. Due to the high bursting strength, these cartons can be stacked without difficulty and withstand loading. The fairly closed, smooth paper surface is well suited for printing and adhesive tapes have good adhesion
Testliner
Kraftliner
Testliner is the cheaper paper variant. In contrast to kraftliners, this liner consists of 100% recycled paper. Compared to kraftliner, testliner therefore usually has somewhat lower quality properties, e.g. in terms of strength. This depends on the grade of the recovered paper used in production. Therefore, there is a further subdivision into T1, T2 and T3: Grade T1 contains the highest-quality recycled papers, while grades T2 and T3 contain correspondingly fewer. In this way, the appropriate packaging quality can be selected according to individual needs. Among other things, this saves costs and protects the environment!
Schrenz
Schrenz
Schrenz is a term for paper made from various recycled fibres, usually produced from unsorted waste paper. This paper is lighter and of low strength. Therefore it is often used as an intermediate liner for multiwall corrugated board.
Kraftliner or testliner?
How can I tell that it is a kraftliner and not a testliner quality? The simple test: If you tear the paper at an angle and see long, even brownish paper fibres, you can be sure that it is a Kraftliner quality. This is because kraft paper consists of virgin fibre papers, whereas with testliner the fibre length is secondary. But why is kraft paper not always dark brown? Firstly, it depends on what kind of wood is used (softwood or hardwood) and secondly, and more significantly, the proportion of recycled fibres. Up to 30% recycled fibres may be used in the production of kraft paper. By using different proportions of recycled fibres, the colour can vary from dark brown to grey-brown.
This chart shows the share of the different paper types in the production of corrugated board in Germany. The only question is how many boxes made of kraft or testliner paper will fit into one of these new Gigaliners for transport…?
