Accelerated ageing tests are widely used in conservation research, either to
predict how long a paper would last or to what extent a certain treatment would
prolong the period during which an object, or its material, will keep the
qualities needed to be used for its intended purpose.
Burst Index
The quotient of the bursting strength of a paper and its grammage in the conditioned
state as defined in the standard method of test.
Bursting Strength of Paper
The strength of paper in pounds per square inch, as measured by Mullen tester.
This is also referred to as burst and pop strength.
Grammage of paper
In metric system, weight (in grams) per square meter of paper or paperboard.
Moisture Content
This is the amount of moisture contained by paper, expressed as a percentage of its
total weight. Average amount ranges from 4-7%. Uniform moisture is a necessity in
all grades of paper. The amount of moisture in a sheet of paper affects basis weight,
printability, physical strength, and runnability.
Opacity
The ability of a sheet of paper to prevent light transmission through it.
High opacity is essential for a paper intended for duplex printing (printing on
both sides of paper), or for intensive color printing on one side of the sheet.
Opacity increases with increase in grammage of sheet. Addition of fillers, dyestuff,
or pigment also increases opacity of paper. However, beating, pressing or calendering
of paper decreases it opacity.
Porosity
A structural property of paper, which refers to resistance of paper to air permeation.
In printing, high porosity is needed in offset papers to decrease the ink consumption.
Tear Factor
Tear factor is calculated as tear strength per unit grammage (g/m2).
Tear Strength
The resistance of a sheet of paper to tearing, as measured by the force required
to tear a strip under standard conditions. Tear strength is an important performance
factor to a printer or converter.
Brightness
Paper, paperboard, and pulp are measured through a lab test to determine the degree
of reflectivity as measured by blue light to determine its brightness level. Paper
brightness affects the legibility and contrast of printing.
Compressibility
Compressibility describes a paper's capacity to be squeezed (upon flat surfaces) and
returned to its prior state. It is an important property of paper when stacks of paper
are placed under compression. It is also known as Cushion.
Density
Density or specific gravity of paper is it weight per unit volume, obtained by dividing
the basis weight by caliper. Paper density (in g/cm2) expresses how compact the paper is.
Edge Crush Test
A test to evaluate the compression strength of containerboard used to manufacture
corrugated shipping boxes.
Gloss
The property of a surface, which causes it to reflect light specularly.
Gloss expresses the amount of directed light that is reflected in a certain direction.
Gloss of paper is measured by Gardner Gloss Meter, which measures the reflected light
at an angle of 75°.
Moisture Content
This is the amount of moisture contained by paper, expressed as a percentage of its
total weight. Average amount ranges from 4-7%. Uniform moisture is a necessity in all
grades of paper. The amount of moisture in a sheet of paper affects basis weight,
printability, physical strength, and runnability.
Peel Test
The peel test has been widely used for the mechanical measurement of the adhesion
phenomenon. However the proportion of the energy input dissipated plastically within
the adhered is a major concern in analyzing peel test data.
Tensile Strength
The force, parallel with the plane of the paper, required to produce failure in a
specimen under specified conditions of loading. Tensile strength is measured in
both the grain and cross-grain directions.
