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UJX 678.51.8 : 620.193.6
IS0
FO R STA N DA RD IZATl O N
I N TERN AT1 ON A L O RG A N IZATl ON
IS0 RECOMMENDATION
R 877
P LAST I CS
DETERMINATION OF RESISTANCE OF PLASTICS
TO COLOUR CHANGE
UPON EXPOSURE TO DAYLIGHT
1 st EDITION
December 1968
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 877, Plastics - Determination of resistance of plastics to colour change upon
exposure to daylight, was drawn up by Technical Committee iSO/TC 61, Plastics, the Secretariat of which is held
by the United States of America Standards Institute (USASI).
Work on this question led, in 1963, to the adoption of a Draft IS0 Recommendation.
In August 1964, this Draft IS0 Recommendation (No. 757) 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 :
Romania
Argentina Hungary
South Africa, Rep. of
Austria India
Belgium Israel Switzerland
Canada Japan Turkey
Czechoslovakia Korea, Rep. of U.A.R.
Finland Netherlands United Kingdom
France New Zealand U.S.A.
Germany Poland U.S.S.R.
Two Member Bodies opposed the approval of the Draft :
Italy
Sweden
The Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council, which decided,
in December 1968, to accept it as an IS0 RECOMMENDATION.
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ISO/R 877-1968 (E)
IS0 Recommendation R 877 December 1968
P LAST I CS
DETERMINATION OF RESISTANCE OF PLASTICS
TO COLOUR CHANGE
UPON EXPOSURE TO DAYLIGHT
1. SCOPE
This IS0 Recommendation describes a procedure for assessing the resistance of plastics to colour change upon
exposure to daylight, under glass.
2. PRINCIPLE OF METHOD
2.1 Test specimens of the plastics material to be tested are exposed to light, together with pieces of the dyed
wool standards specified in IS0 Recommendation R 105/1, Tests for colour fastness of textiles (First series),
Part 1 1 : “Colour fastness to light : Daylight”. These standards vary in colour fastness to light, No. 8 being
the most stable and No. 1 the least stable.
After specified exposure, the degree of contrast between exposed and unexposed portions of the test
specimens is compared with that of the dyed wool standards, and the fastness rating obtained from the
rating of the standard which shows a degree of contrast similar to that of the test specimen.
Provision is also made in this IS0 Recommendation for the use of other standards and other means of
measurement. Related methods are described in the following IS0 Recommendations :
IS0 Recommendation R 878, Determination of resistance of plastics to colour change upon
exposure to light of the enclosed carbon arc;
IS0 Recommendation R 879, Determination of resistance of plastics to colour change upon
exposure to light of a xenon lamp.
2.2 The quality and intensity of solar radiation at the earth’s surface vary with climate, location and time. The
use of the dyed wool standards minimizes the effects of these variations on fastness ratings, but when
plastics materials are to be compared it is preferable to expose them at the same time and place, under
conditions approximating to those expected in service. While radiation may affect other properties of
plastics, this method pertains only to its effect on colour.
3. APPARATUS
3.1 Exposure case
The exposure case consists essentially of an open-bottomed box, covered with a framed lid of glass and
containing a removable rectangular rack for carrying the test specimens and the wool standards. The rack
rests upon a supporting screen made of wire cloth. Ventilating holes, 20 mm (0.75 in) in diameter, are
provided in the upper side of the exposure case, their centres being approximately 75 mm (3 in) apart and
13 mm (0.5 in) above the upper surface of the battens. These holes are covered with wire mesh.
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ISO/R 877-1968 (I
Suitable dimensions for the apparatus are given in Figure 1 (page 10) and Figure 2 (page 11).
The exposure case should be situated in the open and facing south in the northern hemisphere, north in the
southern hemisphere. It should be so supported on legs that its lower front edge is 760 mm (30 in) from the
ground. The lid, rack and screen should all be inclined at 45 to the horizontal.
The exposure case should be so placed that no obstruction in an easterly, southerly or westerly direction
(in the northern hemisphere), or in an easterly, northerly or westerly direction (in the southern hemisphere)
subtends an angle of more than 20 with the horizontal at the centre of the case. No obstruction in a
northerly direction (in the northern hemisphere) or in a southerly direction (in the southern hemisphere)
should subtend an angle of more than 70 with the horizontal at the centre of the case.
3.1.1 Lid. The lid (see Fig. 1) of the exposure case consists of a framed sheet of good-quality flat glass 3 mm
thick, uniformly transparent and without defects, and having a transmittance of less than 1 below
300 nm and at least 90 from 370 to 380 nm and in the visible region of the spectrum. It hasan
unobstructed free area with length and width at least 90 mm (3.5 in) greater than the corresponding
dimensions of the space occupied by the test specimens. When in position, its lower surface is 75 mm
(3 in) from the upper surface of the rack; the lid fits snugly and symmetrically into the case.
3.1.2 Ruck. The removable rack consists of horizontal wooden battens attached at each end to side frames,
as shown in Figure 1. The battens are so arranged that there is an air-space 50 mm (2 in) wide between
them.
A series of 38 mm (1.5 in) wide wooden flaps are so hinged to the battens that the lower 38 mm
(1.5 in) strip of each batten may be covered. The hinges are so arranged that
(U) when each flap is held parallel to the batten, there is a space of 3.0 mm (O. 12 in) between flap and
batten, and
(b) when each flap is allowed to fall freely, its lower edge rests upon the batten.
Removable opaque cover strips are provided so that portions of the test specimens can be protected from
light at different stages of exposure, in accordance with clause 5.4. Cover strips, when in place, should
be in close contact with the test specimens.
The rack fits snugly into the exposure case. When in position, the lower surface of the rack rests
immediately on the upper surface of the wire screen.
3.1.3 Wire screen. The screen is made from woven wire cloth with mesh aperture about 0.16 mm (0.0063 in).
The wire cloth is supported on a rectangular frame (removable for cleaning), incorporating narrow cross
supports if required. The wire cloth is ftxed to the upper side of the frame so that an area approximately
equal to that of the glass lid is free from obstruction, except for the cross supports. The frame fits
snugly into the exposure case.
3.2 Standards
Blue dyed wool standards No. 1 to No. 8, as specified in IS0 Recommendation R lOS/i, Part 11, clause
3.1.1.* (See Appendix, section Z.1, of this IS0 Recommendation).
3.3 Greyscale
Grey scale for assessing change of colour, as specified in IS0 Recommendation R 105/I, Part 2.* (See
Appendix, section 2.2, of this IS0 Recommendation). In this scale, Grade 1 corresponds to the greatest
degree of contrast, and Grade 5 to zero contrast (two patterns of identical colour).
See IS0 Recommendation R 105/I, Tests for colour fastness of textiles (First series) :
Part 2 : “Grey scale for assessing change in colour”,
Part 11 : “Colour fastness to light : Daylight”.
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ISO/R 877-1968 (E)
4. I'EST SPECIMEN
The test specimen may conveniently be approximately 11 5 mm (4.5 in) in length and 30 niin (O.ü in)
4.1
or more in width.
For film and sheet, the test specimen is cut to size and is of the thickness of the filiii or sheet.
For moulding materials, a moulded sheet of thickness 3 * 0.15 mm is prepared and the test specimen cut
from this, unless other methods of preparation or other thicknesses are prescribed in the specification for
the material.
For materials which may shrink in one direction during the test, the test specimen should be cut with its
long dimension at right angles to this direction, since a change in the length of the test specimen may
displace the limiting line between exposed and unexposed parts and thus diriiinish the sharpness of contrast.
4.2 One test specimen is used. More may be required for materials which are riot of a uniform colour.
A further control specimen (or specimens) is required for cornparison.
5. PROCEDURE
5.1 Test specimens are fied at the top and bottorii on the rnck sc) that the upper 38 rnni (1 5 in) ,ire covered
by the flap, the next 38 rnm (1.5 in) clre freely expobed, And the remaiiii
...