Numerous different types of paper are used in packaging applications, some of which have very different properties. The appropriate type is selected depending upon the requirements placed upon the packaging by the package contents and transport conditions. Some of the most important types of paper are described in the following table:
| Paper grade |
Characteristics and applications |
| Asphalt paper |
Asphalt is a black/brown bituminous mixture of flammable hydrocarbons. Asphalt paper comprises a layer of this substance between two plies of paper. Asphalt paper is highly waterproof and is only slightly permeable to water vapor. Consequently, it is most particularly used for packaging goods which are susceptible to corrosion. Asphalt paper cannot be heat sealed, so water vapor permeability is always a critical factor, which in turn means that it cannot be used as the sole means of corrosion protection. Asphalt paper is merely water-repellent, but is not impermeable to water vapor. |
| Kraftliner |
Due to its high strength and moisture resistance, kraftliner is used as an outer and intermediate ply, especially in corrugated board. The high strength is achieved thanks to the virgin fiber used in the production of kraftliner, which has a low recycled fiber content. |
| Kraft sack paper |
As its name would suggest, kraft sack paper is primarily used for sack/bag production. It is distinguished by elevated elasticity. |
| Wet strength paper |
Special type of paper which has been specially treated, e.g. by coating, lamination or impregnation, to improve its resistance to water and water vapor. Wet strength paper types are in particular used in sacks/bags in order to maintain their tensile strength when exposed to moisture and for cartons if condensation is anticipated in transit. |
| Parchment paper |
In addition to moisture resistance, parchment paper’s most significant advantage is its completely greaseproof nature. It is thus mainly used for packaging greasy or oily or grease-sensitive products. Glassine and imitation parchment paper have similar grease-repellent properties. |
| Gray chip |
Gray chip, also known as schrenz, is used, like kraftliner, in corrugated board manufacture, but for the fluting instead of the outer or intermediate plies. Its recycled fiber content is relatively high. |
| Testliner |
Testliner, like kraftliner, is used for the outer and intermediate plies of corrugated board. However, its strength is not quite as high as that of kraftliner, as it has a higher recycled fiber content. |
| VCI paper (Volatile Corrosion Inhibitor) |
VCI paper provides protection from corrosion. The paper acts as a support for the inhibitors which actually provide protection from corrosion. Further information may be found in the Corrosion Protection section. |
