Topic of your interest
Paper testing
Do you need detailed information on paper specifications ranging from thickness, tensile strength, colour, gloss, printability, water absorption, and ageing resistance? Fogra offers numerous inspections and tests – some by ISO, DIN, or other standards. Here, you will find an overview of the most frequently requested tests. If you cannot find a specific test, contact us.
The general paper tests include paper thickness, specific volume, and fibre orientation. The strength properties and the deformation behaviour include the hygroexpansivity, the picking tendency, and the double fold number according to Schopper and other tests. The surface properties are characterised using roughness, static and dynamic friction coefficients, or contact angle. The optical properties can be specified using colour, gloss, whiteness, and more. The counter print or wipe test, mottling tendency, or inkjet printability are summarised under the printability and writability tests. The absorption of water or oil and air permeability are examined in terms of behaviour towards liquids and gases. The ageing tests examine how resistant, lightfast and durable papers and proof papers are.
General paper testing
Do you need to check manufacturer specifications or have papers analysed that are not specified in detail? Thickness, mass or volume - the general paper testing analyses are the right ones for this.
Paper thickness
ISO 534
What is analysed?
Paper thickness is determined in µm as a single sheet or in a stack.
How is it analysed?
The paper or stack is subjected to a defined pressure. The distance between the two thrust faces is then determined electronically.
What are the benefits of this analysis?
The thickness is essential when selecting paper or designing products. The value can also be used to adjust printing and finishing machines specifically. Thickness measurement can also be used to check manufacturer specifications or analyse unspecified materials.
Grammage
ISO 536
What is analysed?
The mass per unit area of paper in g/m2 is ascertained.
How is it analysed?
A defined-sized circular area is punched out and measured using a precision scale. The grammage can be calculated from the quotient of the weight and the area.
What are the benefits of this analysis?
This value plays a vital role in paper selection or product design. It can be used to check manufacturer specifications or to analyse unspecified materials.
Paper density & specific volume
ISO 534
What is analysed?
The density of paper is established in g/cm3, and the specific volume in cm3/g.
How is it analysed?
Firstly, the paper thickness and the mass per unit area are measured. The density or specific volume results from the quotients of these measured variables.
What are the benefits of this analysis?
The characteristics are required when selecting paper or designing products. These values also help to check manufacturer specifications or unspecified materials.
Fibre orientation
Fogra-Method
What is analysed?
Here, the difference in tensile strength is determined in percent from two different tensile directions.
How is it analysed?
Paper strips are cut from the test sheet at an angle of 30° and -30° to the machine direction. The tensile strength is determined on both strips.
What are the benefits of this analysis?
The difference in tensile strength is a parameter for the deviation of the main fibre direction from the machine direction. At high values, diagonal tension and stack skewing can occur.
Absolute moisture
Karl Fischer Method
What is analysed?
The absolute water content is measured as a percentage.
How is it analysed?
The paper is tested with a Karl Fischer titrator using a headspace sampler.
What are the benefits of this analysis?
The water content influences the printing, finishing, and dimensional behaviour of papers. In practice, the relative moisture content is usually of interest. However, the absolute moisture content can provide additional information for manufacturers in the event of defects.
Ash content 525 °C
ISO 1762
What is analysed?
The proportion of inorganic components such as fillers, pigments, and calcium carbonate (coating) is determined as a percentage.
How is it analysed?
The paper to be analysed is incinerated at 525 °C in the oven. The mass percentage of ash in the original total weight is identified by differential weighing.
What are the benefits of this analysis?
The ash content provides information about the chemical composition of the paper. Comparative measurements can also be used to conclude any fluctuations in production.
Ash content 900 °C
ISO 2144
What is analysed?
The percentage of inorganic components is established, whereby the carbonate content is extracted.
How is it analysed?
The paper sample is incinerated in the oven at 900 °C. Differential weighing determines the proportion of the original total weight accounted for by the remaining ash.
What are the benefits of this analysis?
The characteristic value provides information about the chemical composition of the paper. If the ash content measurements at 900 °C and 525 °C are compared, the carbonate or coating content can also be determined.
Strength properties and deformation behaviour of paper
The paper has a wide variety of strength properties and deformation behaviour. These include residual, bending, splitting, and coating strength, but also dust tendency or elongation at break, foldability, and creasability. All these properties influence printing or serve as a quality feature.
Tensile strength or elongation at break
ISO 1924-2
What is analysed?
The tensile strength in or across the fibre direction is determined in kN/m. The maximum elongation can also be specified as a percentage.
How is it analysed?
Thin strips of paper are pulled apart at their ends at 20 mm/min using a tensile tester until they tear. At this point, the force or elongation is measured.
What are the benefits of this analysis?
The tensile strength is an indicator of the resilience of papers. It is particularly significant for web presses. In extreme cases, web breaks can occur there.
Residual strength in the fold
Fogra-Method
What is analysed?
The tensile strength of heatset papers is measured in N/15 mm after drying and folding in or across the fibre direction. The papers are also classified according to their suitability for heatset printing machines.
How is it analysed?
Thin paper strips are dried with hot air in the "Fogra-HOT" laboratory dryer and folded with the "Fogra-FI" folding instrument. The tensile strength is then determined.
What are the benefits of this analysis?
Thermal and mechanical stresses during the heatset process reduce the strength of the fold. This can lead to individual pages tearing out after stitching. By measuring the residual strength, the paper's suitability can be ensured in advance, or the cause can be localised in case of a complaint.
Coating strength in the fold (inside fold method)
ISO/TS 23885
What is analysed?
The coating strength of coated papers in the inner fold is assessed as a percentage of the surface area. The test is carried out across grain direction.
How is it analysed?
Paper strips are folded in a defined manner using the "Fogra-FI" folding instrument. A force impulse transfers loose coating particles from the inner fold to a dark surface. Their quantity is determined by image analysis.
What are the benefits of this analysis?
Coating breakage in the inner fold and the associated coating dust deposits reduce the quality of printed products (e.g. books). A laboratory test can ensure the paper's suitability in advance or identify the causes of complaints.
Coating strength in the fold (outer fold method)
Fogra-Method
What is analysed?
The coating strength of coated paper in or across the grain direction in the outer fold is determined as a percentage of the surface area.
How is it analysed?
After printing paper strips on the test printing device, they are folded in a defined manner using the "Fogra-FI" folding instrument. The area of the line break can be identified by analysing the image of the outer fold.
What are the benefits of this analysis?
The quality of various folded products is impaired by line breaks in the outer fold and the associated broken fold edges. A laboratory test is carried out in advance to ensure the suitability of the paper or to identify the cause in the event of complaints.
Hygroexpansivity (max. 68 %)
ISO 8226-1
What is analysed?
The change in length of paper is ascertained in or across the fibre direction when the relative humidity increases from 33 % to 68 %. The resulting percentage value refers to the length at 50 % humidity.
How is it analysed?
Paper strips are hung in a special climate chamber and weighted down with light weights. Saturated salt solutions generate the required humidity levels. After a certain conditioning time, the strip lengths are measured and the corresponding characteristic value is calculated.
What are the benefits of this analysis?
The paper behaviour at high humidity levels can be investigated using hygroexpansivity up to 68 %. The results also provide information on moisture-related dimensional changes in certain printing processes, such as offset printing. These can influence the register accuracy and flatness of the prints.
Hygroexpansivity (max. 86 %)
ISO 8226-2
What is analysed?
The change in the length of paper in or across the fibre direction is gauged, which results from an increase in relative humidity from 33 % to 86 %. The value refers to the length at 50 % humidity and is given as a percentage.
How is it analysed?
Paper strips are suspended and weighed down with low weights in a climate chamber. The required humidity can be generated with the help of saturated salt solutions. After a specific conditioning time, the characteristic value can be calculated from the measured strip lengths.
What are the benefits of this analysis?
By measuring the hygroexpansivity up to 86 %, the behaviour of paper at very high humidity levels can be investigated. The results also provide information on moisture-related dimensional changes in certain printing processes, such as offset printing. These changes can influence the register accuracy and the flatness of the printed products.
Picking resistance
ISO 3783
What is analysed?
The speed at which printing with a test oil first leads to picking or delamination marks on the paper is measured in m/s.
How is it analysed?
A paper strip is printed with a test oil of low, medium, or high viscosity on an IGT test printing device. During this process, the printing speed increases linearly. The start of picking is determined visually. The corresponding printing speed can be deduced from the distance to the start of printing.
What are the benefits of this analysis?
Picking is a common problem in offset printing that leads to reduced print quality and increased washing cycles. The picking resistance test can be carried out to find suitable papers or causes of complaints.
Blistering
Fogra-Method
What is analysed?
The tendency for blistering during printing in the heatset offset process.
How is it analysed?
The paper is printed on both sides with a heatset test ink with a high ink film thickness and dried in a defined way with "Fogra-HOT". This is followed by a visual assessment of the blister formation.
What are the benefits of this analysis?
The test can be used to check the paper's suitability for heatset web offset. It can also be used to process complaints.
Dry dusting
Fogra-Method
What is analysed?
The tendency to dry dusting.
How is it analysed?
The paper surface is vacuumed with a special suction nozzle. Loose paper components are loosened in the process. These are collected with black filter paper and visually analysed.
What are the benefits of this analysis?
A high tendency to dry dust can lead to contamination of the blanket or build-up. The test can be used to determine whether the paper is responsible for frequently required washing processes.
Wet dusting
Fogra-Method
What is analysed?
The tendency to wet dusting.
How is it analysed?
A certain number of paper layers are successively rolled over by a micro-grained metal roller, which is immersed in a tub of test liquid (water or fountain solution). The paper components released by the liquid collect in the tub. This is then emptied over a black filter paper. The collected residues are analysed visually.
What are the benefits of this analysis?
Contamination of the blanket or build-up can be caused by a pronounced tendency to wet dusting. This test makes it possible to determine whether the paper is responsible for the frequently required washing cycles.
Bending stiffness (beam method)
DIN 53121/ISO 2493-1
What is analysed?
The bending stiffness is determined under static conditions in or across the fibre direction. The value refers to the width and is given in mNm.
How is it analysed?
A strip of paper clamped on one side is bent at a defined angle at a defined distance using the so-called two-point method. The characteristic value is calculated from the force to be applied and the sample width.
What are the benefits of this analysis?
Bending stiffness is very important when selecting paper for certain print products. It also impacts finishing processes and the runnability in the printing press. The test can be used to ensure that the required specifications are met.
Bending stiffness (resonance method)
DIN 53123-1/ISO 5629
What is analysed?
The bending stiffness is ascertained under dynamic conditions in or across the fibre direction. The value related to the width is given in mNm.
How is it analysed?
The resonance method is used for the measurement. Here, the length-variable free end of a strip of paper clamped on one side is excited to vibrate at a certain frequency. The characteristic value is calculated based on the length at which the maximum amplitude is reached and the mass per unit area.
What are the benefits of this analysis?
The test is important when selecting paper for specific print products. The bending stiffness influences the finishing processes and the runnability in the printing press. Measuring it ensures that the required specifications are met.
Splitting resistance according to Brecht-Knittweiss
DIN 54516
What is analysed?
The resistance that a paper or cardboard offers to splitting perpendicular to the plane of the sheet is determined. It is specified as a length-related force in kN/m.
How is it analysed?
The paper or cardboard sample is glued between two hinged metal jaws using double-sided adhesive tape. These are clamped in a tensile machine in such a way that a uniform attack occurs along one of the edges. The force that causes the sample to split is determined.
What are the benefits of this analysis?
The splitting resistance is a quality feature of paper and cardboard. A value that is too low can favour delamination and peeling. The parameter can be used to check suitability or determine the cause in the event of a complaint.
Internal bond strength (Scott-Bond)
DIN ISO 16260/TAPPI T 569
What is analysed?
The energy required to abruptly split a paper or cardboard is measured. The bond strength is specified in J/m².
How is it analysed?
The paper or cardboard sample is fixed between an aluminium plate and a metal tangle using double-sided adhesive tape. A pendulum then strikes the metal tangle with a defined mass and speed. The energy absorbed during the splitting of the sample is measured.
What are the benefits of this analysis?
The internal bond strength is a quality feature for paper and cardboard. Delamination and peeling can be favoured by a value that is too low. This test can clarify whether papers or cardboard are suitable for printing and where possible causes of complaints can be found.
Creasability
DIN 55437:2008
What is analysed?
The creasability of a folding boxboard is assessed both visually and technically. The folding factor is specified as a dimensionless value.
How is it analysed?
The cardboard sample is creased using various parameters. The creasing is then visually checked to ensure it is free of defects (no cracking) and the creasability range is determined. The folding factor is determined by the ratio of the bending stiffnesses between the uncreased and the creased sample.
What are the benefits of this analysis?
It is an important quality feature for folding boxboard. A large creasability range means that the cartonboard is well suited for folding boxboard applications. The test also helps to identify the causes of complaints.
Tearing resistance according to Elmendorf
ISO 1974
What is analysed?
The average force required to tear a cut paper further is ascertained in mN.
How is it analysed?
Clamped in a special testing device, the paper samples are cut in a defined manner and then torn by applying force. The force required for this is documented.
What are the benefits of this analysis?
The quality feature of tearing resistance is specified in certain standards, such as ISO 9706 for ageing resistance by a defined minimum value. The test result can be used both for suitability testing and in the event of complaints.
Folding endurance by Schopper
ISO 5626
What is analysed?
A Schopper apparatus is used to quantify the number of double folds a paper undergoes until it tears.
How is it analyed?
A thin strip of paper is clamped between two clamps under a defined tensile force. At the height of the centre of the strip, it is folded alternately forwards and backward along the same line. To do this, two opposing blades press the paper through a narrow slit.
What are the benefits of this analysis?
The folding endurance is an important stability property of paper products that are folded frequently during use. These include maps, for example. Their service life depends, among other things, on the number of double folds of the paper used.
Surface properties
These tests are particularly important for finishing and printing properties.
Roughness according to Bendtsen
DIN 53108/ISO 8791-2
What is analysed?
The roughness according to Bendtsen is determined in ml/min. The value measures the air volume flow that can flow between a flat surface and the paper surface.
How is it analysed?
A certain air pressure is generated in the interior of a circular measuring head. Air can escape between the lateral border and the unevenness of the paper underneath. A certain volume flow is required to maintain the pressure, which is measured.
What are the benefits of this analysis?
In addition to haptics, roughness influences numerous finishing properties as well as the tendency to rub off and ink deposit. The parameter can be determined for suitability testing or to find the cause of complaints.
Roughness depth according to Parker-Print-Surf
ISO 8791-4
What is analysed?
The roughness according to Parker-Print-Surf is calculated in µm. This corresponds to the average distance between a flat surface and the paper surface.
How is it analysed?
Air flows between two ring-shaped chambers of a defined measuring head through the gaps formed by the partition wall and paper unevenness. A certain pressure difference is maintained in the process. The volume flow required for this is measured and converted into the characteristic value.
What are the benefits of this analysis?
In addition to the haptics, the roughness has an effect on numerous further processing properties as well as the tendency to rub off and ink deposit. The value can be used to check the suitability of the paper and determine the causes of complaints.
Request measurement of the roughness according to Parker-Print-Surf
Coefficient of static and dynamic friction (slip angle)
DIN 53119-2
What is analysed?
The coefficient of static and dynamic friction of two superimposed layers of paper is established.
How is it analysed?
The paper to be analysed is placed on a horizontal plane. A strip of paper fixed under a friction shoe is placed on top of it. The plane is tilted until the friction shoe begins to slip. The static friction is calculated from the angle of inclination. The dynamic friction results from the time required to cover a certain distance.
What are the benefits of this analysis?
The values are important for the paper feed in printing and finishing machines. They are used for suitability testing or to determine the cause of complaints.
Contact angle
What is analysed?
The contact angle between a (coated) paper surface and a test liquid is measured.
How is it analysed?
A drop of a test liquid of a defined volume is placed on the paper surface using a contact angle measuring device. A high-speed camera determines the angle between the paper surface and the drop surface from the side.
What are the benefits of this analysis?
The contact angle is a measure of the wettability of the surface with a specific liquid. This is an important prerequisite for a trouble-free printing process. The measurement can, therefore, be carried out for suitability testing or to determine the cause of complaints.
Surface energy
What is analysed?
The surface energy of a (coated) paper surface is determined in mN/m.
How is it analysed?
The contact angles of several test liquids with known surface tension are determined on the paper to be analysed. From this, the surface energy and its polar and dispersed components can be calculated.
What are the benefits of this analysis?
The surface energy indicates how well a paper can be printed with certain inks and what type of further processing (e.g. lamination) is possible with it. It is usually determined to test the suitability of papers and to find the causes of any defects.
Optical characteristics
These tests are particularly important for the selection of paper and product design. These include colour and gloss properties in particular.
Colour 45°/0° - D50
ISO 13655
What is analysed?
The LAB values are determined in measuring mode M0, M1 or M2 on a white (wb) or black (bb) measurement backing.
How is it analysed?
The measurement is carried out with a standard hand-held spectrophotometer of your choice.
What are the benefits of this analysis?
The colour values describe the visually perceived paper colour under the respective lighting and viewing conditions. On this basis, the papers can be categorised by PSO (ISO 12647-2). Predefined specifications can also be checked.
Colour d/0° - C
ISO 5631-1
What is analysed?
The LAB values are measured using diffuse illumination for illuminant C and 2° standard observer.
How is it analysed?
A stack of paper consisting of at least ten layers is measured using a spectrophotometer with sphere geometry. The UV component of the illumination is adjusted to illuminant C by using edge filters.
What are the benefits of this analysis?
The colour determined in this way is a common parameter in the paper industry for indoor applications. The measurement result can be used to check manufacturer specifications or to analyse unspecified materials.
Colour d/0° - D65
ISO 5631-2
What is analysed?
The LAB values for illuminant D65 and 10° normal observer are ascertained with diffuse illumination.
How is it analysed?
A stack of paper consisting of at least ten layers is measured using a spectrophotometer with sphere geometry. Beforehand, the UV component of the illumination is adjusted to illuminant D65 by using edge filters.
What are the benefits of this analysis?
The colour determined in this way is a common parameter in the paper industry for outdoor applications. The value makes it possible to check manufacturer specifications or to analyse materials that are not specified in more detail.
Optical brightener content
ISO 15397
What is analysed?
A measure for the content of optical brighteners is determined.
How is it analysed?
The D65 Brightness is measured both with and without a UV filter. The optical brightener content is calculated from the difference between the two values.
What are the benefits of this analysis?
This value influences the intensity of colour changes caused by different UV components in the lighting. It can be used in particular to match the print run and proof paper in the best possible way.
TAPPI gloss 75°
ISO 8254-1
What is analysed?
The TAPPI gloss at 75° is defined using a converging light beam and the value is given in gloss units.
How is it analysed?
Under defined conditions, the light reflection on the paper surface is measured at the specular angle. This is put in relation to the reflection of a glass standard with 100 gloss units.
What are the benefits of this analysis?
TAPPI gloss is the gloss value usually specified by manufacturers. It plays an important role in paper selection and product design. This test allows manufacturers' specifications to be checked or non-specified materials to be analysed.
DIN gloss 75°
ISO 8254-2
What is analysed?
The DIN gloss is determined at 75° using a parallel light beam. The value is given in gloss units.
How is it analysed?
The light reflection on the paper surface is measured at the specular angle under defined conditions. The result is put in relation to the reflection of a glass standard with 100 gloss units.
What are the benefits of this analysis?
Gloss is important for paper selection and product design. Although the TAPPI method is usually used in practice, the DIN 75° gloss can provide additional information for complete characterisation.
DIN gloss 45°
DIN EN 14086
What is analysed?
The DIN gloss at 45° is assessed using a parallel light beam. The value is displayed in gloss units.
How is it analysed?
The light reflection on the paper surface at the specular angle is measured under defined conditions and put in relation to the reflection of a glass standard with 100 gloss units.
What are the benefits of this analysis?
Gloss is important when selecting paper and designing products. The DIN 45° gloss is preferable for high-gloss papers, even if the TAPPI process is usually used in practice.
Gloss (20°, 60° and 85°)
ISO 2813
What is analysed?
The gloss values are measured at 20°, 60° or 85° and specified in gloss units.
How is it analysed?
The light reflection on the paper surface is measured at the specular angle. The characteristic value is determined relative to the reflection of a glass standard with 100 gloss units. Glossy samples are measured at 20°, and matt samples at 85°.
What are the benefits of this analysis?
The gloss has a significant influence on paper selection. In addition to the TAPPI gloss, the measurement method described here is used in particular to match the print run and proof paper in the best possible way.
CIE whiteness – D65/10°
ISO 11475
What is analysed?
The CIE whiteness is determined for illuminant D65 and 10° standard observer.
How is it analysed?
A spectrophotometer with sphere geometry is used, in which the UV component of the illumination has been adjusted according to illuminant D65. The CIE tristimulus values are measured for a stack of at least ten layers of paper. The characteristic value is calculated from this.
What are the benefits of this analysis?
The CIE whiteness D65 is commonly used in the paper industry for outdoor applications. Manufacturer specifications can be checked, and unspecified materials analysed.
CIE whiteness – C/2°
ISO 11476
What is analysed?
The CIE whiteness is determined for illuminant C and 2° standard observer.
How is it analysed?
The CIE whiteness can be determined using a spectrophotometer with sphere geometry, in which the UV component of the illumination has been adjusted according to illuminant C. The parameter is calculated from the measured CIE tristimulus values of a stack consisting of at least ten layers of paper.
What are the benefits of this analysis?
The value is common in the paper industry for indoor applications. It can be used to check manufacturer specifications and unspecified materials.
ISO Brightness
ISO 2470-1
What is analysed?
The reflection factor in the blue spectral range is determined as a percentage for diffuse lighting with illuminant C.
How is it analysed?
A stack of at least ten layers of paper is measured at 457 nm using a spectrophotometer with sphere geometry. The UV component of the illumination must be adjusted to illuminant C by using edge filters.
What are the benefits of this analysis?
This parameter, which the paper industry uses for indoor applications, makes it possible to check manufacturers' specifications or to analyse materials that are not specified in more detail.
D65 Brightness
ISO 2470-2
What is analysed?
The reflection factor in the blue spectral range is measured as a percentage under diffuse lighting with illuminant D65.
How is it analysed?
A stack of at least ten layers of paper is measured at 457 nm using a spectrophotometer with sphere geometry. Beforehand, the UV component of the illumination must be adjusted to illuminant D65 using edge filters.
What are the benefits of this analysis?
This parameter, which the paper industry commonly uses for outdoor applications, can be used to check manufacturers' specifications or to analyse materials that are not specified in more detail.
Opacity
ISO 2471
What is analysed?
The opacity (paper backing) of a paper in the visible area in per cent.
How is it analysed?
The value is measured using a spectrophotometer with sphere geometry. The reflectance factors of a sheet of paper over a black cavity and a stack of at least ten layers of paper are measured. The results are set in relation to each other to calculate the characteristic value.
What are the benefits of this analysis?
Opacity describes the extent to which a sheet obscures underlying printed matter on the same paper. That is important in paper selection and product design. Its determination allows to check manufacturer specifications or to analyse unspecified materials.
Printability & writability
How ink behaves on paper is tested in these tests.
Mottling tendency
Fogra-Method
What is analysed?
The tendency to mottling is analysed in the case for overprinting and back splitting.
How is it analysed?
A two-coloured print (magenta on cyan) is made wet-on-wet on the IGT test printing device. This is then rolled over twice by a blanket roller. A visual or image-analysed assessment of the mottling is carried out on the test print produced in this way.
What are the benefits of this analysis?
Mottling is a visually disturbing effect. It can reduce quality, especially in even areas. By analysing the mottling tendency, it is possible to determine the extent to which the paper is responsible.
Wipe test
Fogra-Method
What is analysed?
How even the paper surface is with regard to the absorption of offset printing inks.
How is it analysed?
A special wipe test ink is applied evenly to the paper to be tested using a spatula. After a certain exposure time, excess ink is scraped off the paper surface and wiped off with an absorbent cloth. The brightness distribution is then assessed visually or by image analysis.
What are the benefits of this analysis?
The wipe test is used to visualise the distribution of surface pores on coated papers and the partial absorbency on uncoated papers. Both can contribute to uneven printing. The wipe test can therefore be used to find possible causes of mottling.
Counter print test
Fogra-Method
What is analysed?
The extent to which offset printing ink can be deposited from the printed front side onto the unprinted reverse side.
How is it analysed?
The paper is printed on the prüfbau test printing device with a special ink setting test ink. After various time intervals, counter prints are made on unprinted paper. The amount of ink transferred to the counter paper is assessed visually.
What are the benefits of this analysis?
Ink set-off leads to a reduction in the quality of the printed product. The counter-print test can be used to determine whether a paper is susceptible to this. It also provides information on the ink setting behaviour. It is, therefore, usually carried out to determine the cause of such defects.
Ink writability
DIN 53126
What is analysed?
Whether the paper can be written on with water-based ink.
How is it analysed?
A drawing device is used to draw straight lines in and across the fibre direction under defined conditions using a drawing nib and standard test ink. The paper is considered writable if the strokes do not run out, bead, or strike-through.
What are the benefits of this analysis?
Ink writability is essential for writing papers. It can be used to determine whether papers are suitable as such.
Inkjet printability (incl. certificate)
FFPI-SP 08
What is analysed?
How long the drying time of a label inkjet print on paper or cardboard is.
How is it analysed?
A labelinkjet print head prints a DataMatrix code onto the substrate. After different periods, the code is passed under a wiping unit. The codes treated in this way are analysed with a verifier and checked for readability.
What are the benefits of this analysis?
In the pharmaceutical and packaging industry, the "label capability", particularly of folding boxboards, is an important criterion for the substrates and inks that can be used. This test can be carried out to determine suitability or in the event of complaints.
Behaviour towards liquids and gases
Whether and how much water or oil a paper absorbs or how much air it lets through is tested with these tests.
Water absorption (Cobb)
ISO 535
What is analysed?
How much water in g/m2 is absorbed via the surface within a certain time.
How is it analysed?
The paper is clamped between a water-filled metal container and a flat lid. The composite is turned upside down for a certain period. The paper is then taken out, and excess water is removed. The characteristic value can be determined from the difference in weight before and after contact with water and the surface area.
What are the benefits of this analysis?
Water absorption influences the printability, coatability, and bondability of papers. A high absorption capacity is important for water-based inkjet printing and dispersion coating, for example. Analysing water absorption can indicate the causes of problems in printing or further processing.
Oil absorption (Cobb-Unger)
Based on ISO 535
What is analysed?
The amount of castor oil that can be absorbed over the surface in g/m2 within a defined period of time.
How is it analysed?
The samples are clamped between an oil-filled metal container and a flat lid. After the composite has been turned upside down for a set time, the paper is removed, and excess oil is removed. The characteristic value is calculated from the difference in weight before and after oil contact and the surface area.
What are the benefits of this analysis?
Oil absorption plays a particularly important role in offset printing. This is because the papers have to absorb the low-viscosity oils of the printing inks. It therefore has a significant influence on the drying process and related properties. Analysing oil absorption can provide information on the causes of problems in printing practice.
Air permeability according to Bendtsen
DIN 53120-1/ISO 5636-3
What is analysed?
The air permeability of the paper according to Bendtsen in µm/Pas. This value corresponds to the flow velocity per unit of pressure.
How is it analysed?
Clamped between a ring-shaped surface and a seal, a constant overpressure is generated on one side of the paper. The air permeability is calculated from the measured air volume flow per unit of time and the surface area.
What are the benefits of this analysis?
Air permeability is of interest for certain products, such as food packaging. It can also influence the paper feed or the blocking tendency of dispersion-coated print products. Determining this helps to identify the causes of specific application problems.
Ageing
These tests examine how durable papers and proof papers are. This also includes light fastness and stability requirements.
Permanence (incl. certificate)
ISO 9706
What is analysed?
The ageing resistance of papers is verified.
How is it analysed?
As part of the test, the pH value in the cold water extract, the kappa number, the alkali reserve, and the tearing resistance according to Elmendorf are determined. If all values are within the specified limits, conformity with the standard is attested by a certificate.
What are the benefits of this analysis?
This makes it possible to identify papers that exhibit a high degree of durability. If they are stored in a protected environment over long periods, they show little or no changes that affect legibility and handling.
Light fastness
ISO 12040
What is analysed?
The resistance to artificial lighting with xenon arc light is determined in the form of colour changes.
How is it analysed?
The samples are irradiated in a defined temperature and humidity range for a certain period. The period is calculated according to the desired light fastness level. This is measured using the so-called wool scale. Colour measurements are taken before and after irradiation.
What are the benefits of this analysis?
Light fastness is an important parameter in quality assurance and the durability of products made with paper. Testing them ensures that they meet the desired standards.
Proof paper resistance
ISO 12647-7/-8
What is analysed?
Under climatic conditions typical for test prints, the ageing resistance is measured in the form of colour changes.
How is it analysed?
The paper to be analysed is successively exposed to three climatic scenarios in the dark: 1) 24 h at 25 °C and 25 % relative humidity, 2) 24 h at 40 °C and 80 % relative humidity, 3) 7 d at 40 °C and 10 % relative humidity. Colour measurements are taken before and after.
What are the benefits of this analysis?
This test ensures the resistance of proof papers that are to be used worldwide.
Stability requirements for general graphical applications (incl. certificate)
ISO 20494
What is analysed?
The extent to which papers change as a result of the ageing process during normal storage.
How is it analysed?
As part of the test, the pH value in the cold water extract and the alkali reserve are determined. The tearing resistance, according to Elmendorf, is measured before and after accelerated ageing. If all values are within the specified limits, conformity with the standard is confirmed with a certificate.
What are the benefits of this analysis?
Compliance with ISO 20494 is often required when documents are created and stored over a long period. It can be checked to determine suitability or in the event of complaints.