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I NT ERN AT1 ON AL O RG A N IZATl O N
fO R STA N D A RD I ZATl O N
IS0 RECOMMENDATION
R 137
DETERMINATION OF WOOL FIBRE DIAMETER
PROJECTION MICROSCOPE METHOD
1st EDITION
January 1960
COPYIZIGWT 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 137, Determination of Wool Fibre Diameter-Projection
Microscope Method, was drawn up by Technical Committee ISO/TC 38, Textiles, the
Secretariat of which is held by the British Standards Institution (B.S.I.).
At its first meeting, held in Buxton in June 1948, the Technical Committee decided to
add the subject of fibre testing to its programme of work and to appoint a Sub-Committee
SC 6, Fibre Testing, to deal with it.
At its second meeting, held in Bournemouth in June 1951, the Technical Committee
approved a recommendation from the Sub-Committee SC 6 that methods for the determi-
nation of fibre number or fineness should be developed.
When detailed attention was given to the question of wool fibres, the Sub-Committee
SC 6 agreed that a method evolved by the International Wool Textile Organisation (IWO)
should be taken as the basis of its work. A first draft proposal on those lines was subse-
quently prepared and was unanimously adopted at the third meeting of the Technical Com-
mittee, held in Southport in May 1956, as a Draft IS0 Recommendation.
On 15 October 1957, the Draft IS0 Recommendation (No. 181) was distributed to all
IS0 Member Bodies and was approved, subject to some editorial amendments, by the
the
:
following Member Bodies
Australia Hungary Portugal
Austria India Romania
Belgium Israel Spain
Burma Italy Sweden
Canada Japan Switzerland
Czechoslovakia Netherlands Turkey
Denmark New Zealand United Kingdom
France Norway U.S.A.
Pakistan U.S.S.R.
Germany
Greece Poland
No Member Body opposed the approval of the Draft.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0
Council, which decided, in January 1960, to accept it as an IS0 RECOMMENDATION.
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IS0 / R 137 - 1960 (E)
-
IS0 Recommendation R 137 January 1960
DETERMINATION OF WOOL FIBRE DIAMETER
PROJECTION MICBoSC!OPE ME'TI-IOD
FOREWORD
The method of measuring fibre diameter by the projection microscope is used throughout the
world in various forms and is thus appropriate for international standardization. The method is
suitable for wool fibres in any form and also for other fibres of reasonably circular cross-section.*
1. SCOPE
This method sets out the procedure and the conditions of measurement for the determination of
wool fibre diameter by means of the projection microscope.
2. PRINCIPLE
The principle of the method consists of projection on a screen of the images of the profiles of
wool fibre pieces and measuring the width by means of 8 graduated scale. The operating technique
assures a random sampling of the fibres to be measured.
3. APPARATUS
3.1 Microtome
For preparing the test specimen, use a microtome, an instrument for cutting the fibres to a
determined 'length.
The microtome consists of a steel plate with a slot atrd a $tee1 tangue, Axed to the guides
which slide along the plate, adjustable in such a manner that it enters the Slat t6 a pre-
determined distance. A steel blade pusher is equal in thickness to the width of the microtome
slot and has a stop plate placed at a determined distance from ont of its ends: a set of three
pushers should be available, the stop plates of which are placed at distances of 0.8 mm,
0.6 mm and 0.4 mm from one of their ends.
TABLE l.-Choice of pushers
Fibres Pushers
I Distance between stop plate
Average dhfer
and @ushet's end
Form
micrdns p flillliniertes
t 1.
I
0.8.
> 27
Slivers and rovings
0.4
< 27
0.6
> 27
0.4
< 27
* In the case of dyed, bleached or finished fibres, it should be noted that the diameter may be different from that of fibres not subjected
to such treatments. The estimates of fibre diameter obtained at the various stages of processing one lot of wool willnot necessarily be the same.
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ISO/R 137 - 1960 (E)
3.2 Projection microscope
The projection microscope comprises a light source, a light condenser, a stage which
supports the prepared fibres, an objective, an ocular and a circular screen.
3.2.1 The stage is movable in two directions at right-angles by means of an intermediary
sliding mechanism capable of successive displacements at 0.5 mm steps.
3.2.2 The objective and ocular are capable of providing 500 x magnification.
3.2.3 The circular screen is able to rotate around its centre in its plane.
If this screen is not transparent, it should carry a transparent scale, 5 cm wide, graduated
in millimetres along its underside; this scale can be moved diametrically across the screen
between guides.
Transparent screens may carry scales graduated in millimetres along one diameter or
along two perpendicular diameters.
In the centre of the circular screen there is a circle whose diameter is equal to a quarter
of the optical distance between the ocular and the centre of the screen. All measurements
are made inside this circle.
3.2.4 Calibration. The projection microscope should be calibrated periodically by means of
a micrometer scale (certified accurate), divided in hundredths of a millimetre and placed
on the stage. One division of the micrometer (i.e. 0.01 mm), projected on the screen,
should cover exactly 5 mm of the graduated scale. The magnification is then equal
to 500 x .
3.3
Mounting medium (for the preparation of the specimen)
Provide a mounting medium with the following properties :
(a) a refractive index between 1.43 and 1.53,
(6) suitable viscosity,
(c) zero water absorption.
Cedar wood oil and liquid paraffin are examples of suitable media.
4. PREPARATION OF SPECIMENS
4.1 Sampling
Specimens in the form of sliver, roving or yarn are placed in the slot of the open microtome,
occupying the slot to a sufficient depth. Long fibres are generally thick fibres, and con-
sequently any manipulation resulting in selection of long fibres will give too great an
average diameter. Raw wool or loose fibres in any form are sampled as described in
Appendix 1.
4.2 Conditioning
Condition the fibres to equilibrium in an atmosphere whose relative humidity is 65 f 2 per
cent and temperature 20 f 2 OC."
* See IS0 Recommendation R 139, Standard Atmospheres for Conditlonlng and for Determlnlng the Physlcal and Mechanlcal Properfles
of Textlles.
-4-
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IS0 / R 137 - 1960 (E)
4.3 Cutting by microtome
Place the specimen in the microtome slot. Then insert the steel tongue and push it strongly
to compress the sliver. With a razor-blade cut off the projecting fibres flush with both faces
of the steel plate. The cut part of the fibres will then remain in the microtome slot. By forcing
the pusher from one side, the cut fibres will appear on the opposite side, at the length of
0.8 mm, 0.6 mm and 0.4 mm, according to the pusher used. With a razor-blade, cut the
emerging fibres flush with the steel plate.
4.4 Mounting of specimens
Place all the fibres cut with the microtome on a slide and mix with a few drops of mounting
medium until the specimens are completely and evenly distributed.
Remove sufficient of the mixture before covering the slide to ensure that no oil is squeezed
from under the cover-glass when it is placed on. This will ensure no preferential removal of
thin fibres.
5. PROCEDURE
5.1 Examination of the specimen
The slide is then placed on the microscope stage, the cover-glass towards the objective.
After the fibres have settled, the specimen is examined in different fields. The distance
between the centres of the fields should be theoretically greater than the length of the cut
fibres, otherwise the same cut fibre could be measured twice. However, if the centres are
only 0.5 mm apart, the probability of measuring the same cut fibre twice is s
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