Paper Standards Measur Umschlag - Sappi Mobile

Paper
Standards & Measurements
sappi

Sappi is committed to helping printers and graphic designers use paper in the best possible way. So we share our knowledge with
customers, providing them with samples, specifications, ideas, technical information and a complete range of brochures. Find out
more on our unique web site
www.sappi.com/KnowledgeBank

Paper
Standards & Measurements
Content
l Introduction 3
ll Paper Specification 4
Basis weight 4
Thickness / Caliper 4
Specific volume 4
Relative humidity 4
III Optical Properties 5
Gloss 5
ISO-Brightness 5
CIE-Whiteness 6
Shade (colour) 6
Opacity 6
Metamerism 6
Fluorescence 6
Yellowing 6
IV Surface Properties 7
PPS roughness 7
Smoothness 7
Surface roughness (laser profile) 7
Picking resistance 7
IGT 7
Prüfbau 7
V Strengths 8
Tensile strength and breaking length 8
Elongation (stretch at break) 8
Tearing resistance 8
Residual strength 9
Bursting strength 9
Stiffness (rigidity) 9
Scott Bond 10
Blister test 10
Vl Absorption 11
Water absorption Cobb 11
Oil absorption Cobb-Unger 11
Ink absorption / Set-off 11
Water absorption – Drop test (Prüfbau) 11
Ink repellence – IGT 12
Contact angle measurement 12
Penetration Dynamic Analyzer (PDA) 12
VlI Others 13
pH value 13
Ash content 13
Mottle test 13
Ink rub resistance 14
Cracking test 14
VIIl List of Standards and Measures 15
IX Concluding remarks 16
X Table of recommended units 17
XI Table of conversion factors 18
1

l Introduction
This brochure is a small summary of the very extensive
publications of DIN and ISO standards. It has been produced
to help explain the most important standards and units without
complicated mathematical formulas and with simple
words.
The paper properties are arranged into different groups, so
that the emphasis in the requirements of the paper becomes
clear. Therefore some overlaps cannot be avoided.
3

ll Paper Specification
A paper specification is a list of characteristics with appropriate
measured values, which the paper has to fulfill. The
measured values are indicated with their tolerances. A specification
is necessary, since this shows the requirements of
the customer and forms the basis, that always the same
paper is supplied. In order to come to a specification, one
must know the intended purpose and the requirements of
the paper. Discussions with the customer or consumer are
the correct way to co-ordinate the requirements of the
paper and the possibilities in paper production.
Basis weight ISO 536
The weight in g/m 2 is understood by the basis weight of a
paper under conditioned circumstances. The entire mass is
the sum of fibrous materials, fillers, process materials and
water.
Thickness / Caliper ISO 534
The thickness of a paper is measured between two even
plates, which are adjustable with a defined pressure. Because
of the compressibility and the inhomogeneity several
measurements have to be carried out and the results averaged.
The thickness of a paper is dependent on grammage
and specific volume.
Specific volume ISO 534
The thickness is expressed in micrometers (µm). To compare
the thickness of papers with different basis weights, the
specific volume is used. This is the thickness to which the
basis weight of 100 g/m 2 refers. This calculation is carried
out according to the formula:
Thickness (µm) divided by the basis weight is the specific
volume (cm 3 /g).
4
The picture above shows the most important optical and physical characteristics,
in so-called Datasheets are listed. These can request or with your personal
partner receive you at any time in the Internet.
Relative humidity Tappi 502
The relative humidity indicates how many percent of the maximum
possible water vapour portion, at a certain temperature
is actually in the air (i.e. between the sheets of a stack or the
windings of a reel).
L&W Micrometer

lII Optical Properties
The first impression of a paper is its colour, its whiteness and
its gloss. The appearance of the paper is of course important
when it is sold, but the optical properties are also important
when the paper is printed on. In order to be able to
manufacture paper with the right optical properties, pulp
and coating raw materials, paper technologists must have
access to good measurement methods.
The optical characteristics of the paper are affected by the
measurement of reflection, absorption or transmission of
light which strikes a sheet of paper.
Whiteness and shade of the paper do not have direct influence
on the printability but have an influence on the printed
result. Colour printed on bright white underground results in
another impression than printed on other white undergrounds.
The ISO12647-2 standard used for the colour management
in the graphic arts industry provides a colour-correct reproduction
with the consideration of the paper type.
Gloss ISO 8254-1 (DIN)
ISO 8254-2 (Tappi)
A calendered, coated or varnished paper has a high proportion
of direct reflection, which is commonly called gloss.
Gloss is an important characteristic in the production of
coated papers. The gloss makes paper look elegant and the
property is therefore important for advertising print. Gloss is
measured with special instruments where the sample is illuminated
with parallel light at a certain incidental angle. Fixed
optical geometries, incidental and reflection angles of 75, 60
or 20 degrees, are usually used. A specific geometry and
angle is used, based on paper quality and gloss level. The
following gloss standards are common: DIN 45° or 75° and
Tappi 75° or 20°.
DIN standard and/or low angle are used for (ultra) high gloss
levels.
Gloss can also be measured on a printed area and is called
print gloss.
ISO-Brightness ISO 2470
The brightness is a measure for the reflection of blue light of
the paper expressed in a percentage in comparison with an
ultimate reference brightness standard (IR3 standard).
There are three brightness values for fluorescent papers:
ISO-brightness under C-light, D65-brightness under D65
light and brightness with fluorescence eliminated.
The higher the brightness value, the brighter the paper is.
Papers with optical whitening agents show a peak in the
blue reflection. This addition of blue reflection causes the
sample to appear whiter to the observer and gives higher
ISO-brightness and D65-brightness values. The ultraviolet
energy level of the illumination must be adjusted using a
fluorescent calibration standard.
L&W Gloss Tester
5

CIE-Whiteness ISO 2470
Whiteness is a subjectively perceived property. Most people
consider that it increases when the material has a slightly
blue tone. It is thus clear that whiteness in some way is an
aspect of colour perception, and that any measurement of
whiteness must be based on colour management.
Shade (colour) ISO 5631
Shade of a paper is the colour of a paper. The colour is described
as blue, green, yellow or red or as a mixture of these
colours. The colour can be described according to intensity
and saturation. There are several different systems in use,
but most common for the paper industry is the CIE L* a* b*.
Opacity ISO 2471
The opacity is a measurement for the light transparency
degree of the paper, expressed in a percentage in relation to
the reflected light. Paper which lets a lot of light through is
transparent; paper which lets less light through is opaque.
The higher the value, the more opaque the paper is.
Metamerism
Metamerism is the condition in which two colours can
appear identical under certain light sources but exhibit clear
differences in other light sources. This occurs because the
reflective/reflection curves of the metameric colours are not
the same/alike over the whole spectrum.
Fluorescence
If a colour becomes more optically intensive under a certain
light source it is due to the effect of fluorescence. This
occurs when parts of the incident light are reflected in other
wavelengths. The impact of fluorescence is shown by the
optical brighteners used in many papers as they convert UV
light into visible light.
6
Yellowing DIN 6167
Degree of yellowing / discolouration of paper exposed to daylight
or heat, after a specified period of time. A test piece is
exposed for a specified time to UV light or heat. Colour measurements
at specific time intervals describe the yellowing /
discolouration. The degree of yellowing is expressed in a yellowing
number.
Elrepho

IV Surface Properties
Paper is a surface product, its surface determines the visual
impression and the feel. Beyond that, printing techniques,
converting techniques and application determine the characteristics
of the paper surface.
PPS roughness ISO 8791-4
The geometric form of a paper surface is defined as deviation
from the ideal dead level. The more the surface approaches
the ideal level, the smoother the paper is. The
measuring method (PPS) is based on the measurement of
the air leakage between the paper surface and an even
measuring head. In case of the PPS roughness, the depth of
the pores is measured by a defined circle. The higher the
measured value is, the “rougher” the paper surface is.
Smoothness ISO 879/-2/3 und ISO 5627
Definition and measuring method are comparable with
those used for roughness. Depending upon measuring
technology either the time is measured in which a certain
amount of air is used (Bekk and Gurley) or airspeed is measured
under a constant pressure (Bendtsen or Sheffield).
Apart from the air flow measurement principles there is also
the optical smoothness measurement according to FOGRA
and IGT method for determination of print smoothness.
Surface roughness (laser profile)
By use of a laser profile device it is possible to make a 3D
topographical roughness profile of the paper surface. Every
component’s surface has some form of texture which varies
according to its structure. These surfaces can be broken
down into three main categories: Surface roughness, Waviness
and Form.
With this measurement it is possible to analyze defects of
the paper surface related to the paper machine.
Picking resistance
The picking resistance of a paper is the strength of the paper
surface (Z-direction). In the offset printing process there are
forces on the paper surface caused by splitting of the ink
(tack) and adhesion forces of the blankets. Individual fibers,
coating particles or whole surface areas can be pulled out.
The picking resistance can be determined according to
different methods:
IGT ISO 3783
The IGT and Prüfbau picking tests show rather good correlations
with picking demands in the offset printing process.
The principle of the test methods is to simulate as much as
possible the print conditions. With the IGT method oils with
different viscosity are used in combination with accelerated
speed. The selection of a combination of oil and speed is
dependent on the kind of paper (LWC, WFC etc.).
Prüfbau
With the Prüfbau-test special test inks or commercial inks
can be used to perform a picking test. It is also possible to
pre-wet the paper with fountain water to determine the wet
pick. The adjustable parameters such as pressure, speed,
printing roller and time interval must be taken from the test
provisions and be tuned with the respective type of paper
and its application.
Prüfbau
7

V Strengths
The strength of paper plays an important role during production
but especially at converting of the paper. The
strength is in many cases also important for the use of
paper. A paper, which is produced as a reel is subject to a
tensile force in linear direction, a paper which is produced as
a sheet is subject usually to a tensile force in transverse direction.
Depending on the forces on the paper there are test
methods, which can objectively determine if the paper’s
strength is sufficient for these demands (forces).
Tensile strength
and breaking length ISO 1924-2
The testing of the paper on tensile strength takes place via
tear test under a defined increasing force. The measured
tensile strength value is the quotient of the force (N) at the
moment of break and the width of the test strip. The tensile
strength index is the quotient of the tensile strength and the
grammage (g/m 2 ) of the paper.
The breaking force (N) and the grammage are the basis for
calculating the breaking length. The breaking length is the
length of a strip of paper with a defined width, when, freely
suspended, it tears due to its own weight.
Elongation (stretch at break) ISO1924-2
The elongation at rupture defines the stretch of a paper in
percentage (%) at the time of tearing in relation to the unloaded
length. The elongation at rupture is simultaneously
measured with the breaking force. From the breaking force
and elongation graph the elasticity module can be calculated.
This elasticity module is related to the dimensional stability
of the paper in different printing and converting processes.
8
Tearing Tester
Tearing resistance ISO 1974
The mean force required to continue the tearing of an initial
cut in a single sheet of paper is expressed as the internal
tearing resistance. If the initial slit is made in the machine
direction, the result is given as machine direction tearing
resistance and similarly for the cross machine direction.
Tensile Tester

Residual strength FOGRA
Residual strength is an important characteristic for web offset
papers. In web offset the paper is printed, heated and
folded. During this process the paper should have a specific
residual strength to prevent web breaks and breaks on the
fold.
Under standardized circumstances a paper is heated and
folded. Directly afterwards the tensile strength of the test
piece is determined.
A general method for residual strength is the FOGRA
method. With this method the residual strength of the paper
should be higher than a minimum value of 0.67 kN/m.
Bursting strength ISO 2758
The bursting strength is expressed as the maximum uniformly
distributed pressure, applied at right angles to its
surface that a single sample piece can withstand under test
conditions. The Burst index is the bursting strength divided
by the grammage.
Stiffness (rigidity) ISO 5628
The stiffness is an important characteristic of the paper,
because it has substantial influence on the runability properties
during the printing process and on the requirements for
converting (folding, creasing etc.). Stiffness is defined as
resistance against bending in the elastic area of the paper.
Beside grammage and thickness there are other items
which have influence on the stiffness, such as choice of raw
materials, refining degree of the fibers, quality and amount of
filler and moisture content. The extent of the bend follows
the laws of mechanics, which means the paper is not damaged
when stretched on the outside and compressed on
the inside. There are different methods available to determine
the stiffness but the most used method in the paper
industry is the 2-points load method. With this method the
force needed to bend a rectangular test piece to a specified
angle is measured. The stiffness in machine direction and
cross direction are the key factors.
Bursting Strength Tester
9

Scott-Bond Tappi T 569
ZDT Tappi T 541
Internal bond strength (paper’s strength in its thickness
direction) is an important characteristic during printing and
converting processes. Internal bond strength is the maximum
load that single ply or multiple paper or boxboard can
withstand when loaded with a force directed at right angles
to the surface of the sample material. The paper’s ability to
withstand these forces depends on factors such as choice
of pulp, degree of beating and refining, paper machine settings
and choice of additives.
The Z-directional tensile and Scott Bond tests are different
methods. The ZD-tensile measures the maximum force to
split the sample at a low standardized test speed perpendicular
to the test surface. The Scott Bond method measures
the energy needed to split the sample at a speed several
thousand times higher.
Internal bond is related to several phenomena during
printing and converting such as delaminating, blistering,
creasability etc.
Blister test
With the Blister test the drying section of a HSWO printing
press is simulated. The blister oil test has proven to be a
good test to determine the blister resistance in practice. The
paper is put in an oil bath with a specific temperature and
the water located in the paper evaporates, just as happens
in the drying section of the HSWO printing press. Blistering
can occur if the temperature is too high, the internal bond
too low or the vapour permeability too low. Printed areas
with a high coverage of ink (300–400%) are more sensitive
for blistering. Papers used for HSWO should show no
blistering at a temperature of 160–170°C or 340-360°F.
10
Scott-Bond Tester

Vl Absorption
Types of paper for offset printing should have a certain
absorption to give the ink a good adhesion and to store the
fountain water (temporarily). The absorption level should not
be so high that printing ink and fountain water show through
the paper. The absorption is an important property of the
paper during the printing process and is a crucial factor for
paper-ink-fountain water interaction studies.
Water absorption Cobb ISO 535
Dependent on the intended purpose, different measuring
methods for the determination of the water absorption ability
were developed. An old method is with the help of a pulling
feather/spring to apply a coloured ink on the paper with a
specific increasing width and observe if the ink spreads out
or shows through. With the ink swimming test the measure
of gluing is likewise tested. Both testing methods are limited
to printing and writing papers.
For papers which are printed in offset the absorption is often
determined with the Cobb test. The water absorption is determined
by measuring the amount of water, which is taken
up by the paper within a specific time. The Cobb test gives
only reliable values, if the paper is not fully soaked through
with water.
Cobb Sizing Tester
Oil absorption Cobb-Unger FOGRA
The Cobb test can also be used for the measurement of oil
absorption instead of water and is called the Cobb-Unger.
Ink absorption / Set-off
The set-off of paper describes the absorption of ink on the
paper. The speed of absorption is determined by the time
that the ink needs to penetrate into the paper. For the offset
process this property is very important. An absorption which
is too slow, may result in smearing because the ink does not
dry fast enough. An absorption which is too fast, may result
in a reduction of the dry ink properties.
The set-off of paper can be measured with a test printing
machine like Prüfbau or IGT.
A sample is printed with a standard ink. After several time
intervals, a part of the printed sample is countered against a
blank counter sheet of the same paper (top on bottom in
order to simulate a pile). The density of the transferred ink of
each area on the counter sheet is measured and plotted
against time.
The shorter the time from high ink transfer to no ink transfer
of the counter sheet the faster the set-off.
Water absorption – Drop test (Prüfbau)
The drop test is carried out using the Prüfbau printing
machine. A drop of a defined Isopropylalcohol solution is
applied to the paper sample by means of a micro-pipette
and the paper is immediately printed with an ink. The ink
densities in the pre-wetted and dry printed areas are measured.
The ink density in the pre-wetted area is expressed
as a percentage of the ink density in the dry printed area.
The higher the value, the lower is the ink repellence of the
paper.
11

Ink repellence – IGT
If the flow rate of fountain solution is high and/or the paper
has poor water-absorbing characteristics, the film of fountain
solution on the surface of the paper results in repulsion
of the ink in the following printing unit. Depending on the extent
of the repulsion, solid areas can show an uneven printout.
The ink repellence test is carried out using the IGT test-printing
machine. Dampening is performed using an engraved
steel roller dampened with fountain solution. The printing
unit of the IGT tester is situated below the dampening unit,
which allows the first section of the paper strip to be printed
dry. The second section of the paper strip is printed after
dampening and is designated as the first interval. There is a
time interval of 0.05 seconds between wetting and printing.
The printing densities of the solid area (dry printing) and the
pre-wetted area are measured. The mean value of the
dampening interval is expressed as a percentage of the
mean value of the solid area. The higher these values are,
the lower is the ink repellence of the paper.
Contact angle measurement Tappi-558
With determination of the absorptive capacity of paper for
liquid it is necessary to define clearly, which liquid it concerns,
how long the time of contact will be and under which
conditions the test is implemented. In most cases where a
liquid droplet is applied to a solid material, an angle is
formed at the point of contact between droplet and solid,
the so called wettability angle or contact angle. This contact
angle is an indication of the wetting performance of liquids
applied to solids. This contact angle must be determined immediately,
because the liquid could penetrate rapidly into the
pores of the paper. Many printing inks, oils, paraffins and
similar products have rather a low surface tension and are
spreading immediately on the paper surface. Contact angle
measurements and wetting studies can be performed using
an automated contact angle tester.
12
Penetration Dynamic Analyzer (PDA)
With this test it is possible to measure process relevant
parameters of paper, coating colours or chemicals like glue
and ink with the aim of predicting printability, glueability and
ability for coating.
A paper sample is brought into contact with liquid in a measuring
cell. From the moment of liquid contact, it is radiated
in the Z-direction with high-frequency low-energy ultrasonic
signals. These signals are received by a highly sensitive
sensor before they are processed in the device and transmitted
to a personal computer. The main advantage of this
method compared to other methods is that the penetration
dynamics can be tracked in real time with millisecond time
resolution.
Drop test: Paper with a good water absorption
Drop test: Paper with a bad water absorption

Vll Others
pH value ISO 6588
The pH value in the data sheets defines the pH value of the
surface. The pH values are indicated on a scale from 0 to 14.
The measuring value 7 marks the neutral point which corresponds
to distilled water. Values below 7 refer to “increasingly
acid”, values above 7 stand for “increasingly alkaline”.
Papers should be close to, if possible, next to the neutral
area or in the slightly alkaline range to have ideal requirements
for printing and further treatment.
Ash content ISO 2144
The ash content is the remaining residue as percentage of
dry paper after ignition at 900°C. The ash content is the total
of inorganic material, like carbonate, kaolin etc. in the paper
(including filler). Fillers have an important influence on the
paper quality (for instance opacity) and are dosed with care
depending on the application of the paper.
Mottle test
Mottling is the uneven print appearance, mostly in solid
areas: small dark and light areas in the surface of paper
(board) caused by ink, paper or printing press. Mottle is influenced
by many parameters: e.g. ink, colour sequence,
construction of printing press, speed, rubber blanket and
fountain water. Variations in the surface characteristics such
as absorption and smoothness play an important role
regarding mottle and are caused by the production process
and the components within the paper.
There can be three kinds of mottle:
Backtrap mottle
Ink applied to paper surface on a preceding printing unit of a
multi-colour press will split onto the blanket in a subsequent
unit and then be re-deposited onto the next sheet. If this
occurs unevenly, the print can become mottled.
This backtrap mottle can be simulated on a test printing
machine by printing the paper and countering the paper in
pre-defined times against a clean blanket reel.
Water interference mottle
Water transferred to paper surface on a preceding printing
unit of a multi-colour press should be absorbed by the coating
before it reaches a subsequent printing unit. If it is not
absorbed it will prevent even transfer of the ink. A mottled
print can result.
The method IGT ink repellence (see chapter VI Absorption)
is used to test this phenomenon.
Midtone mottle (screen mottle)
This is an uneven print in 30–60% screens, caused by differences
in the scattering and absorption behaviour of base
paper and/or coating. This effect can occur in one colour
printing and even in case of perfectly formed dots of equal
density (optical effect).
Midtone mottle can be evaluated by printing a screen with
the test printing machine or with help of a plastic screen
which is put on top of the paper. The level of screen mottle
can be evaluated visually or with help of image analysis.
13

Ink rub resistance Prüfbau
Rubbing is the effect of repeated relative shifting of two
touching surfaces under a certain amount of pressure. The
measure of resistance of a printed material to this rubbing
effect is known as ink rub resistance.
Ink rub resistance can be determined with the Prüfbau ink
rub tester. 48 hours after printing the ink rub resistance is
visually evaluated. It is also possible to evaluate the ink rub
resistance with a spectrophotometer or with image analysis.
Cracking test DIN 55437
After the printing process the paper is mostly converted to
brochures, books, maps etc.
During converting when the paper is folded, cracking of the
coating can occur at the folds.
Papers below 170g/m 2 are directly folded, whereas papers
equal or above 170g/m 2 are creased before folding. Folding
can be carried out with the Fogra folding tester. Fold is
visually evaluated for cracking.
The creasability of a paper is tested with a special machine,
which has a creasing knife and different rules.
Papers which can be creased within a wide range (combinations
depths and widths) without showing faults, have a
good creasability level. Papers that can only be creased
without showing faults within a small range have a bad
creasability level.
14

Vlll List of Standards and Measures
Selection of ISO/DIN/TAPPI and FOGRA test methods
Unit Europe US
Paper Specification
Basis weight g/m2 ISO 536 Tappi T 410
Thickness / Caliper µm ISO 534 Tappi T 411
Specific volume cm2 /g ISO 534 Tappi T 500
Relative humidity % Tappi 502 Tappi T 502
Optical Properties
Gloss % ISO 8254 – 1 and 2 Tappi T 480
ISO-Brightness % ISO 2470 Tappi T 452
CIE-Whiteness ISO 11475 Tappi T 562
Shade ISO 5631 Tappi T 524 or T 527
Opacity % ISO 2471 Tappi T 425
Metamerism
Fluorescent
Yellowing DIN 6167
Surface Properties
Roughness PPS µm ISO 8791-4 Tappi T 555
Smoothness Bekk sec. ISO 8791-2/3 and ISO 5627 Tappi T 479
Surface roughness (laser profile)
Picking resistance
IGT ISO 3783 Tappi T 514
Prüfbau
Strengths
Tensile strength and breaking length kN/m – km ISO 1924-2 Tappi T 494
Elongation % ISO 1924-2 Tappi T 494
Tear resistance mN ISO 1974 Tappi T 414
Residual strength kN/m FOGRA
Bursting strength kPa ISO 2758 Tappi T 403
Stiffness mN.m ISO 5628 Tappi T 556
Scott Bond / ZD Tensile J/m 2 – kPa Tappi T 569 – Tappi T 541 Tappi T 569 – Tappi T 541
Blister test ° Tappi T 526
Absorption
Water absorption Cobb g/m 2 ISO 535 Tappi T 441
Oil absorption Cobb-Unger g/m 2 FOGRA
Ink absorption / set-off test (Prüfbau)
Water absorption (Drop test)
Ink repellence – IGT
Contact angle measurement Tappi T 558 Tappi T 558
Penetration Dynamic Analyzer
Others
pH-Value ISO 6588 Tappi T 509
Ash content % ISO 2144 Tappi T 211 and T 413
Mottle test
Ink rub resistance
Cracking test DIN 55437
15

lX Concluding remarks
The contents of this brochure result from extensive research
work, closely linked with practice and with practical experience.
We would like to take this opportunity to thank the following
company for their support and assistance
Lorentzen & Wettre
16493 KISTA, Schweden
All statements and information are correct to the best of our
knowledge. All liability for losses associated with suggestions
given in this brochure is excluded, regardless of the
legal basis. The right is reserved to make technical changes
to our grades in the course of further development.
All rights reserved
© 2007 by Sappi Europe SA
Imprint
Sappi Fine Paper Europe
Text and Editing:
Herrmann Nax, Maurice van Duuren
16

X Table of recommended units
We hope this list of most frequently referred units and properties within this catalogue will be a useful tool for all who are involved
in the pulp and paper field. Recommended units are from the International Standard, ISO 5651.
Property Recommended unit or
method of expression
Adhesion on strength of glue bonds
of corrugated fiberboard
kN/m
Air permeance µm/(Pa s)
Air resistance (Gurley) s
Apparent bulk density g/cm3 Apparent sheet density g/cm3 Ash % (mass/mass)
Bending stiffness µm, mNm, Nm
Bending stiffness index Nm7 /kg3 Box compression resistance BCT kN
Breaking length km
Bulking thickness µm
Burst energy absorption Jlm2 Burst index kPa m2 /g
Bursting strength kPa
Compression resistance SCT kN/m
Compression resistance SCT index kNm/kg
Conductivity of extracts mS/m
Dimensional change after
immersion in water
%
Dirt and shives in pulps 102 (number of specks)/kg
Drainability of pulp –"CSF"
and Schopper-Riegler
numerical value
Edgewise crush resistance kN/m
Electric strength kV/mm
Flat compression resistance kPa
Flat crush resistance FCT
(corrugated board)
kPa
Flat crush resistance of
laboratory fluted corrugated medium N
Fold number, double folds numerical value
Folding endurance log 10 (number of folds)
Fracture toughness J/m
Fracture toughness index Jm/kg
Friction coefficient N/N
Gloss % or numerical value
Grammage g/m2 Hygroexpansivity %
Ink absorbency “K and N” “K and N” units
Light absorption coefficient m2 /kg
Light absorbing power numerical value
Property Recommended unit or
method of expression
Light scattering power numerical value
Light scattering oefficient m2 /kg
Moisture content or dry
matter content
% (mass/mass)
Opacity %
Picking velocity, IGT m/s
Puncture resistance J, kJ
Reflectance factor %
Reflection (optical) density numerical value
Resistance to water penetration min, h, d
Resistance to grease penetration min, h, d
Ring crush kN/m
Roughness, Print-surf µm
Roughness, Bendtsen ml/min
Saleable mass kg
Surface resistivity Ohm
Smoothness, Bekk s
Static bending force mN, N
Stock concentration %
Stretch at break %
Swelling after water immersion %
Tear index mNm 2 /g
Tearing strength N
Tensile index N m/g
Tensile energy absorption J/m 2
Tensile stiffness N/m
Tensile stiffness index Nm/kg
Tensile stiffness orientation ° (degree with decimal
(polar angle) sub-divisions)
Tensile strength kN/m
Tensile toughness index Jm/kg
Tensile toughness J/m
Thickness µm,mm
Transmission (optical) density numerical value
Volume resistivity Q m
Water absorbency g/m2 – area basis g/m2 – mass basis %
– capillary rise mm
Water vapour transmission rate g (m2 d)
z-direction strength properties kN/m2 17

Xl Table of conversion factors
Most of the world has accepted the International System of “Units-Systeme International d’Unités” (SI) as the standard system
for measurement. Test methods and standards require SI units as the primary reporting value. We trust that this guide will be
useful when converting between different units (FPS foot-pound-seconds and SI units).
FPS unit Faktor Sl-unit
A
acres 4046.86 m 2
B
Btu (IT) 1.055056 kJ
Btu/h 0.29307 W
Btu/(h·ft·oF) 1.7307 W/(m·K)
Btu/(h.ft2 . OF) 5.6783 W/(m 2 ·K)
Btu/lb 2.326 J/g
Btu/(lb·oF) 4.1868 x 103 J/(kg·K)
F
fl oz (Imp) 28.413 cm 3
fl oz (US) 29.574 cm 3
ft H20 (39,2 °F) 2.98898 kPa
ft 0.3048 m
ft 2 0.09290304 m 2
ft 3 0.02831685 m 3
ft/min 5.08 mm/s
ft/min 0.00508 m/s
ft 3 /min 1.69901 m 3 /h
ft/s 0.3048 m/s
ft 3 /s 28.31685 l/s
ft·lbf 1.355818 J
ft·lbf/in 2 2.1015 kJ/m 2
ft·lbf/ft 2 14.5939 J/m 2
ft·lbf/s 1.35582 W
G
gal(US) 3.785412 I
gal(lmp) 4.546092 I
gal(US)/d 0.00378541 m 3 /d
gal(US)/min 3.785412 I/min
gal(lmp)/min 7.5768 x 10- 5 m 3 /s
gal(US)/min 6.3090 x 10- 5 m 3 /s
grains/yd 2 0.0775 g/m2
H
hp (550 ft-lbf/s) 0.7457 kW
hp·h 2.68452 MJ
I
in 25.4 mm
in 2 6.4516 cm 2
in 3 16.38706 cm 3
inHg (32 °F) 3.38638 kPa
inHg (60 °F) 3.37685 kPa
inH20 (60 °F) 0.24884 kPa
in·lbf 0.1129848 N·m
in·lbf 0.1129848 J
in·lbf/in 2 175.1268 J/m 2
in·ozf 7.061552 mJ
FPS unit Faktor SI-unit
K
Kgf/in 0.38609 kN/m
L
Ib 0.4535924 kg
Ibf 4448.222 mN
Ibf 4.448222 N
Ibf·in 0.1129848 Nm
Ibf/in 2 6.894757 kPa
Ibf/in 175.1268 N/m
Ibf/in 0.1751268 kN/m
Ibf/in 2 6.894757 kN/m 2
Ibf/in 2 6.894757 kPa
Ibf·ft 1.35582 N·m
Ibf/ft 2 47.88026 Pa
Ibf/15 mm 0.29655 kN/m
Ibf·s/ft 2 47.88026 Pa·s
Ibf/ft 3 16.01846 kg/m 3
Ib/1000 ft 2 4.8824 g/m 2
Ib/3000 ft 2 1.6275 g/m 2
Ib/in 3 27.6799 Mg/m 3
Ib/gal (US) 0.1198264 kg/l
Ib/ream, 17 x 22–500 3.7597 g/m 2
Ib/ream, 24 x 36–500 1.6275 g/m 2
Ib/ream, 25 x 38–500 1.4801 g/m 2
M
mi 1.60934 km
mi 2 2.589988 km 2
mil (0,001 in) 25.4 IJm
mil (0,001 in) 0.0254 mm
O
oz (avoir.) 28.34952 g
oz (US fluid) 29.57353 ml
ozf 0.278014 N
ozf/in 10.945 N/m
oz/gal (US) 7.489152 g/l
P
psi 6.894757 kPa
T
ton (short) 0.9071847 tonnes(t)
ton (short)/l 00 ft 2 0.092903 t/m 2
y
yd 0.9144 m
yd 2 0.83612736 m 2
yd 3 0.7645549 m 3
yd 3 /s 0.7645549 m 3 /s
18

Paper Standards & Measurements is one in a series of Sappi’s technical brochures. Through them, we share our paper knowledge
with our customers so that they can be the best they can be.
MOTTLING-
MOTTLED
IMPRESSION
PROCESSING
MATT PAPERS
PAPER, INK AND
PRESS CHEMISTRY
ADHESIVE
TECHNIQUES
ON-PRESS
TROUBLESHOOTING
THE PRINTING
PROCESS
FOLDING AND CREASING
CLIMATE
AND PAPER
For comprehensive technical information
sappi
www.sappi.com/KnowledgeBank
THE PAPER MAKING
PROCESS
The word for fine paper

www.sappi.com
Sappi Fine Paper Europe
Sappi Europe SA
154 Chausseé de la Hulpe
B-1170 Brussels
Tel. + 32 (0) 676 97 00
Fax + 32 (0) 676 96 60
sappi
The word for fine paper
Cover HannoArt Gloss 250 g/m 2 , Text HannoArt Gloss 150 g/m 2 , 2007 Sappi Europe SA