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UDC 676 : 620.1
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IS0
I NTERN AT1 O NA L O RG A N IZAT I O N FOR STA N DARD IZ AT I O N
IS0 R ECO M MEN DATI O N
R 536
DETERMINATION OF PAPER SUBSTANCE
1 st EDITION
January 1967
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
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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BRIEF HISTORY
The IS0 Recommendation R 536, Determination of Paper Substance, was drawn up
by Technical Committee ISO/TC 6, Paper, Board and Pulps, the Secretariat of which is
held by the Association Française de Normalisation (AFNOR).
Work on this question by the Technical Committee began in 1955 and led, in 1963, to
the adoption of a Draft IS0 Recommendation.
In December 1964, this Draft IS0 Recommendation (No. 612) 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 :
Argentina Greece Romania
Australia India Spain
Sweden
Belgium Israel
Brazil Japan Switzerland
Canada Mexico Turkey
Chile Morocco U.A.R.
Czechoslovakia Netherlands United Kingdom
Denmark New Zealand U.S.S.R.
Yugoslavia
Finland Norway
France Poland
Germany Portugal
Three Member Bodies opposed the approval of the Draft:
Italy
Republic of South Africa
U.S.A.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0
Council, which decided, in January 1967, to accept it as an IS0 RECOMMENDATION.
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IS0 / R 536 - 1967 (E)
I SO Recommendation R 536 January 1967
DETERMINATION OF PAPER SUBSTANCE
1. SCOPE
This IS0 Recommendation describes the method of determining the substance of paper.
2. DEFINITION
Substance. Mass of paper, expressed in grammes per square metre, determined under standard
test conditions.*
The result is considered " standard " only when these test conditions include conditioning accord-
ing to IS0 Recommendation R 187, Methodfor the Conditioning of Paper and Board Test Samples.
3. PRINCIPLE
The area of the test pieces and their mass are measured and the mass per square metre is calculated,
all measurements being made on conditioned test pieces.
However, if it is desired that similar characteristics be determined for other conditions, e.g.
" oven dry '' or " as taken ", see Notes in the Annex A to this IS0 Recommendation. In that
case, the results should be qualified by a statement indicating the condition of the test piece.
4. APPARATUS
4.1 Cutting device
The cutting device should normally be capable of repeatedly cutting out test pieces whose
95 cases out of 100, falls to the nearest 1 % of a known area. This should
area, in at least
.
be checked frequently by the method given in clause 4.3.1 below and, provided that the
above accuracy is attained, the mean area obtained in these check tests should be used for
calculating substance.
With certain types of paper it will be found, after carrying out this determination of area,
that test pieces cannot be cut with the accuracy just defined and, in such cases, the area of
every test piece should be determined individually (see clause 4.3).
4.2 Weighing device
The weighing device should be accurate enough, over the range of mass for which it is used,
to measure always to the nearest 0.5% of the actual mass. It should be sensitive enough
to detect a change of &0.2% of the mass to be weighed and, if the device is of the direct-
reading type it should be graduated so that readings may be taken to this degree of accuracy.
For checking of the weighing device, see clause 4.3.2.
* Definition as in term No. 80 of IS0 Recommendation R 135, Paper Vocabulary - Second Series of Xerms.
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IS0 / R 536 - 1967 (E)
Special sheet-weighing devices,
...