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Ref. No.: ISO/R 438 - i965 (E)
IS0
I N T ERN AT I O N A L ORGANIZATION FOR S TA N DARD I ZAT I O N
IS0 RECOMMENDATION
R 438
METHOD FOR THE DETERMINATION
OF THE BULKING THICKNESS AND BULK OF PAPER
1st EDITION
June 1965
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standard,
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian.
Copies to be obtained through the national standards organizations.
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Ref. No.: ISO/R 438-1965/A1-1967 (E)
UDC 676
AMENDMENT 1 - JANUARY 1967
TO IS0 RECOMMENDATION R 438-1965
Amendment 1
to IS0 Recommendation R 438-1965
METHOD FOR THE DETERMINATION
OF THE BULKING THICKNESS AND BULK OF PAPER
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Page 6
Amend the second line of the table to read as follows:
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200 mmp 0.31 in'
Area of pressure foot
(nominal value) (nominal value)
This Amendment is the logical result of the acceptance of IS0 Recommendation R 534-1966,
Determination of the Thickness of Sinqle Sheets of Paper.
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BRIEF HISTORY
The IS0 Recommendation R 438, Method for the Determination of the Bulking Thickness
and Bulk of Paper, was drawn up by Technical Committee ISO/TC 6, Paper, the Secretariat
of which is held by the Association Française de Normalisation (AFNOR).
Work on this question by the Technical Committee began in 1958 and led, in 1961, to the
adoption of a Draft IS0 Recommendation.
In October 1961, this Draft IS0 Recommendation (No. 475) was circulated to all the
IS0 Member Bodies for enquiry. It was approved, subject to a few modifications of an editorial
nature, by the following Member Bodies :
Belgium Greece Romania
Brazil Israel Sweden
Bulgaria Italy Turkey
Czechoslovakia Japan U.A.R.
Denmark
Netherlands United Kingdom
Finland Norway U.S.S.R.
France Poland Yugoslavia
Germany Portugal
Four Member Bodies opposed the approval of the Draft:
Australia Canada India U.S.A.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0
Council, which decided, in June 1965, to accept it as an IS0 RECOMMENDATION.
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ISO/R 438 - 1965 (E)
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IS0 Recommendation R 438 June 1965
METHOD FOR THE DETERMINATION
OF THE BULKING THICKNESS AND BULK OF PAPER
1. OBJECT AND SCOPE
This IS0 Recommendation describes a method of measuring the bulking thickness of papers up
to a substance of 250 g per square metre.
Knowledge of the bulking thickness and of the mass of the paper permits the calculation
of the bulk.
2. DEFINITIONS
2.1
Bulking thickness. Thickness of a single sheet calculated from the measurement of the
thickness of several superposed sheets (called a pack), when a static load is applied.
2.2 Bulk. Volume in cubic centimetres occupied by one gramme of paper in the form of a pack
of superposed sheets.
3. PRINCIPLE
The method is based on the use of a precision dial micrometer to measure the thickness of a pack
of sheets when a static load is applied.
Results for thickness are given in terms of the bulking thickness per sheet.
4. EQUIPMENT
4.1 Precision dial micrometer
This instrument is provided with two parallel plane faces between which the paper is placed
for measurement. One of the faces should be capable of movement in a direction perpen-
dicular to the other, which is fixed. The movable face (or pressure foot) should be circular.
The fixed face (or anvil) should also be circular and of such size that the whole area of the
pressure foot is in contact with the anvil in the zero position.
To ensure that the pressure between the faces is uniform within the limits given, the use of
a dead weight rather than a spring is preferred.
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ISO/R 438 - 1965 (E)
The instrument should be checked in accordance with the procedure detailed in the Appendix
and should conform to the following:
Metric system Inch system
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Diameter of pressure foot 16 h 0.5 mm 0.65 0.02 in
Area of pressure foot 200 4 10 mmz 0.31 c 0.015 inz
Pressure exerted by the foot 1.00 i. 0.10 kgf/cm3 14.2 1.5 lbf/in2
Repeatability of measurement
< 0.0025 mm or 0.5 per <0.0001 in or 0.5 per cent*
(standard deviation)
cent*
Indication error I 0.0025 mm or & &0.0001 in or 0.5 per cent *
0.5 per cent*
Error of parallelism of foot and < 0.0050 mm or 1 per <0.0002 in or 1 per cent *
anvil
cent*
4.2 Auxiliary apparatus
A set of feeler gauges of thickness known to within 0.001 mm or 0.000 04 in.
4.3 Calibration of the instrument
The instrument should be calibrated at reasonable intervals. The Appendix gives details
as to the procedure to be followed. For instruments in frequent use, it is suggested that
the calibration be checked daily for repeatability and accuracy, and monthly for parallelism
and foot pressure.
5. PREPARATION OF TEST PIECES
The test pieces (a minimum of four) are composed of the same number of sheets (a minimum of
five). Each sheet is cut to a size of 20 cm x 25 cm** from a specimen taken at random from
those that had been selected according to IS0 Recommendation R 186, Method of sampling
paper for testing, and then cond
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