A variety of tests are used to determine ink and paper and paperboard quality, and to measure their interactions. They are necessary to balance print quality, cost, and wear on the press. Some of the important paper and ink tests are listed here:
Paper test
Paper and ink testing
Tests for paper and ink interaction
A variety of tests are used to determine ink and paper and paperboard quality, and to measure their interactions. They are necessary to balance print quality, cost, and wear on the press. Some of the important paper and ink tests are listed here:
Paper test
A wide variety of paper tests are available, depending on the specific needs and on the governing contract or specification:.
Major paper properties are widely classified into four categories.
Physical Properties
Optical Properties
Mechanical Properties
Miscellaneous Properties
Physical Properties
Grammage or basis weight
Thickness
Bulk
Porosity or Roughness
Dimensional stability
Grammage Test
The mass per area of the paper is measured as GSM (grams per square meter). (Mass is usually measured as weight at a location with sea-level gravity.) Paper sheets are cut to a size of 10 cm × 10 cm, then the sheets are weighed individually. The mean of the weights is used to calculate the mass of the paper per square meter, and the standard deviation is determined from all samples.
Thickness
Defines the thickness of the paper. Consistency of caliper throughout the paper web is an important consideration. An abrupt increase or decrease in caliper can affect the extent to which the printing plate or blanket contacts the paper and transfers a complete printed image, as well as other printability and runability issues.
Bulk
Thickness of the paper in relation with GSM. Not only is consistent thickness required in web offset lithography, where varying bulk within a single roll can cause the roll to unwind with uneven tension, which is responsible for various printing defects as well as web breaks. Higher bulk of the same GSM will reduce the show through defects.
Porosity or roughness
A degree of peaks and valleys on the surface of the paper. High roughness of the paper results in more consumption and many other printability defects, too.
Dimensional stability
A measure of the extent to which a paper will resist a change in size as the result of a change in moisture content. Dimensional instability will result in mis-registration in the press.
Optical properties
Gloss
Whiteness
Brightness
opacity
Shade
Opacity
Opacity is a property of paper that describes the amount of light which is transmitted through it, with paper having a low degree of opacity being more translucent and allowing more light to pass through it. A paper's opacity determines the extent to which printing on a particular side of paper will be visible from the reverse side (called show-through)
Paper shade
Paper shade plays a significant role in the quality of colour reproduction. The shade of the paper affects the colour values of the primary and secondary colours and hence the colour gamut of a press. A wide variety of paper tests are available, depending on the specific needs and on the governing contract or specification:.
Major paper properties are widely classified into four categories.
Physical Properties
Optical Properties
Mechanical Properties
Miscellaneous Properties
Physical Properties
Grammage or basis weight
Thickness
Bulk
Porosity or Roughness
Dimensional stability
Grammage Test
The mass per area of the paper is measured as GSM (grams per square meter). (Mass is usually measured as weight at a location with sea-level gravity.) Paper sheets are cut to a size of 10 cm × 10 cm, then the sheets are weighed individually. The mean of the weights is used to calculate the mass of the paper per square meter, and the standard deviation is determined from all samples.
Thickness
Defines the thickness of the paper. Consistency of caliper throughout the paper web is an important consideration. An abrupt increase or decrease in caliper can affect the extent to which the printing plate or blanket contacts the paper and transfers a complete printed image, as well as other printability and runability issues.