PDF GB/T 1766-2008 English (GB/T 1766-1995: Older version)
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Paints and varnishes -- Rating schemes of degradation of coats
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| GB/T 1766-1995 | English | 479 |
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Paint and varnish--Rating schemes of degradation of coats
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Method of evaluation of degradation (both exterior and accelerated)of paint films
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GB/T 1766-2008: PDF in English (GBT 1766-2008) GB/T 1766-2008
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 87.040
G 50
Replacing GB/T 1766-1995, GB/T 14826-1993
Paints and Varnishes –
Rating Schemes of Degradation of Coats
ISSUED ON. JUNE 04, 2008
IMPLEMENTED ON. DECEMBER 1, 2008
Issued by.
General Administration of Quality Supervision, Inspection
and Quarantine of the People’s Republic of China;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 General rules and rating method ... 5
4 Single-item rating grade ... 6
5 Comprehensive rating grade ... 15
6 Inspection precautions ... 1
7 Test report ... 1
Foreword
This Standard replaces GB/T 1766-1995 Paints and Varnishes - Rating Schemes of
Degradation of Coats and GB/T 14826-1993 Determination Method and Rating of
Pulverization Degree of Paints and Coating.
The major technical differences of this Standard, compared with GB/T 1766-1995 and
GB/T 14826-1993, are as follows.
- This Standard combines the contents of the two standards, and modifies and
improves some of the methods.
- In color grade rating method, for visual colorimetric, add the gray card rating
discoloration content.
- Rating method for pulverization degree is modified to be the adhesive tape paper
method in ISO 4628-6.2007 OR the swan flannelette method in ISO 4628-7.2003.
This Standard was proposed by China Petroleum and Chemical Industry Association.
This Standard shall be under the jurisdiction of National Coating and Paint Standardization
Technical Committee.
Drafting organizations of this Standard. China National Offshore Oil Corporation
Changzhou Coating Chemical Industry Research Institute, Kunshan Shiming Science and
Technology Development Co., Ltd., and Atlas Material Experiment Technology Group Co.,
Ltd.
Main drafters of this Standard. Ji Xiaopei, Zhang Ping, Shi Yilei, and Zeng Cheng.
GB/T 1766 was first-time issued in 1979, and fir-time revised in 1995. This is the
second-time to combine and revise. GB/T 14826 was first-time issued in 1993, and this is
the first-time to combine and revise.
Paints and Varnishes –
Rating Schemes of Degradation of Coats
1 Scope
This Standard specifies the general principles of the rating of coating aging, rating method
of aging single-item index, and comprehensive rating method of decorative coating and
protective coating aging.
This Standard applies to rating of coating aging performance (natural aging and artificial
accelerated aging).
2 Normative references
The articles contained in the following documents have become part of this Standard
when they are quoted herein. For the dated documents so quoted, all the modifications
(excluding corrections) or revisions made thereafter shall not be applicable to this
Standard. For the undated documents so quoted, the latest editions shall be applicable to
this Standard.
GB 250 Gray Scale for Assessing Change in Colour (GB 250-1995, ISO 105/A02.1993,
IDT)
GB/T 9754 Paints and varnishes - Determination of specular gloss of non-metallic paint
films at 20°, 60°and 85°(GB/T 9754-2007, ISO 2813.1994, IDT)
GB/T 9761 Paints and varnishes - Visual comparison of the colour of paints (GB/T
9761-2008, ISO 3668.1998, IDT)
GB/T 11186.2 Methods for measuring the colour of paint films - Part 2. Colour
measurement (GB/T 11186. 2-1989, eqv ISO 7724-2.1984)
GB/T 11186.3 Methods for measuring the colour of paint films - Part 3.Calculation of
colour differences (GB/T 11186. 3-1989, eqv ISO 7724-3.1984)
ISO 4628-6 Paints and Varnishes - rating of film efflorescence - rating of damage
degree, quantity and size in general types - Part 6. rating of adhesive tape paper
efflorescence degree
4.4.1 The cracking grade of film shall be expressed by its cracking quantity and cracking
size. See Table 8 and Table 9 for cracking quantity grade and cracking size grade.
Table 8 Cracking quantity grade
Grade Cracking quantity
0 No visible cracking
1 A few pieces, the crackings are small enough to be negligible.
2 A few, noticeable crackings
3 A medium amount of crackings
4 A large number of crackings
5 Intensive crackings
Table 9 Cracking size grade
Grade Cracking size
S0 No visible crackings under 10 times of magnifying glass
S1 Visible crackings only under 10 times of magnifying glass
S2 Visible crackings under normal sight
S3 Obvious visible crackings under normal sight
S4 Crackings with width almost up to 1 mm
S5 Crackings with width more than 1 mm
4.4.2 If possible, it can also indicate the depth type of crackings. The cracking depth is
mainly divided into three types.
a) Indicate the surface crackings without penetrating film;
b) Indicate the crackings that have penetrated the surface film, but basically without
influences on each film layer at the bottom;
c) Indicate the crackings that have penetrated the whole film system, the base
materials are visible.
4.4.3 Rating expression method of cracking grade. grade of cracking quantity and grade
of cracking size (with bracket). If possible, it can indicate the cracking depth.
For example. cracking 3(S4)b, indicates that the cracking quantity is grade 3, cracking size is grade S4,
and cracking penetrates the surface film but without influencing bottom layers.
4.5 Rating of blister grade
4 ≤3
5 >15
Table 15 Peeling size grade
Grade Peeling area /%
S0 No visible peeling under 10 times of magnifying glass
S1 ≤1 mm
S2 ≤3 mm
S3 ≤10 mm
S4 ≤30 mm
S5 >30 mm
4.7.2 The peeling depth can be indicated according to damaged level of film system.
a) Indicate that surface film is peeled off from its lower-layer film;
b) Indicate that the whole film system is peeled off from the base materials.
4.7.3 Rating expression method of peeling grade. relative area grade and peeling size
grade (with bracket). If possible, it can indicate the peeling depth.
For example. peeling 3(S2)a, indicates that the peeling area is grade 3, peeling size is grade S2, and
surface film is peeled off from lower-layer film.
4.8 Rating of mildew-growing grade
4.8.1 Grade of coating mildew-growing is expressed by quantity of coating
mildew-growing (see Table 16) and mildew-growing size (see Table 17).
Table 16 Mildew-growing quantity grade
Grade Mildew-growing quantity
0 No mildew spot
1 Very few, several mildew spots
2 A few mildew spots
3 A medium amount of mildew spots
4 A large amount of mildew spots
5 Intensive mildew spots
Table 21 Dirty degree
Grade Dirty degree
0 Without dirty
1 Just noticeable, very slight dirty
2 Slight dirty
3 Obvious dirty
4 Large dirty
5 Serious dirty
5 Comprehensive rating grade
Assess the comprehensive grade of film ageing in accordance with the single-item
damage grade in aging test process; it is divided into six grades - 0, 1, 2, 3, 4, 5 and 6,
which represent excellent, good, medium, acceptable, bad and worse of film aging
resistance performance respectively.
It is divided into decorative film comprehensive rating and protective film comprehensive
rating, according to film purpose.
5.1 See Table 22 for decorative film comprehensive aging performance rating.
6 Inspection precautions
6.1 Damages caused by edges of sample plate, 5 mm around the plate hole and foreign
factors shall not be calculated.
6.2 Record each type of damage phenomenon.
6.3 Record and describe if the film has other abnormal phenomenon except for the above
11 items.
6.4 If the film has several damages phenomenon, it shall be rated according to the most
serious item when conducting the comprehensive grade rating.
7 Test report
The test report shall at least include the following contents.
a) All necessary details of tested product;
b) Indicate the number of this Standard;
c) Test results;
d) Test time;
e) Any difference from the specified test method;
f) Test date.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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