- 1 - ICS 77.150.10  
H 61  
 
 
 
 
National Standard  
of the People's Republic of China  
 
 
GB5237.4 - 200X  
Replaces GB 5237.4 -2004  
 
 
Wrought aluminium alloy extruded 
profiles for architecture  
 
Part 4: Powder coating profiles  
  
Draft for approval  
 
 
 
Issue Date: 200X – XX – XX Implementation Date: 200X – XX – XX 
 
 
 
Issued by the General Administration of Quality Supervision, Inspection and 
Quarantine of the People's Republic of China and the  
Standardisation Administration of the People's Republic of China (SAC)  
 
- 2 - GB 52 37.4 - 200X  
 
Foreword  
 
 
 
Sections 4.5.3.1 and 4.5.5 of this Standard are mandatory, whilst the rest are recommended.  
 
GB 5237, “Wrought aluminium alloy extruded profiles for architecture” is divided into six Parts:  
 
− Part 1: Untreated profiles  
− Part 2: Anodi sed profiles  
− Part 3: Electrophoretic coating profiles  
− Part 4: Powder coating profiles  
− Part 5: PVDF coating profiles  
− Part 6: Thermal barrier profiles  
 
This is Part 4 of GB 5237.  
 
This Part replaces  Part 4 of GB 5237.4 – 2004 “Wrought aluminium alloy extrude d profiles for 
architecture – Part 4: Powder coating profiles”.  
 
This Part has been revised with reference to the following Standards: Europe Qualicoat 
Specification, 11th Edition, “Specifications for a Quality Label, for Paint, Lacquer and Powder 
Coatings  on Aluminium for Architectural Applications”; the standards issued by the American 
Architectural Manufactures Association: AAMA 2603 -2005, “Performance requirements and test 
procedures for organic coatings on aluminium extrusions and panels”; AAMA 2605 -2005, 
“Performance requirements and test procedures for high performing organic coatings on aluminium 
extrusions and panels”; AAMA 2605 -2005, “Performance requirements and test procedures for 
superior performing organic coatings on aluminium extrusions and p anels”; and British standard BS 
6496 -1984, “Specification for powder organic coating for application and stoving to aluminium 
alloy extrusions, sheet and performed sections for external architectural purposes.”  
 
The main technical differences between this Part when compared to GB5237.4 -2004 are:  
− coating gloss has been divided into three types;  
− wear resistance of the coating has been added;  
− detergent resistance of the coating has been added;  
− weatherability of the powder coating has been divided into two Grad es, Grade I and Grade II.  
 
Appendices A and B to this Part are normative appendices.  
 
This Part is proposed by the China Non -ferrous Metals Industry Association.  
 
This Part is under the jurisdiction of the National Technical Committee for Standardisation o f Non -
ferrous Metals.  
 
Main organisations that participated in the drafting of this Part:  
Fujian Minfa Aluminium Industry Co., Ltd;  
Guangdong Xingfa Aluminium Co., Ltd;  
Guangdong JMA Aluminium Profile Factory Co., Ltd;  - 3 - Fujian Nanping Aluminium Co., Ltd;  
Chinese Industrial Standard of Non -ferrous Metal Measure Quality Research Institute;  
 
Other units that participated in the drafting of this Part:  
Non-ferrous Metal Quality Supervision and Inspection Centre of the People's Republic of China;  
Non-ferrous Meta l Quality Supervision and Inspection Centre of South China;  
Nippon Paint Shenglianda Co., Ltd;  
Sichuan Sanxing Aluminium Industrial Co., Ltd;  
Foshan Nanhai Huahao Aluminium Profile Co.,Ltd  
 
Main drafters of this Part:  ChenSuMei, WuXiKun, LuJiYan, FengDong Sheng, ZhangJiLin, 
ZhuYaoHui, HeYaoZu, ZhanHao, MaCunZhen.  
 
This Part replaces the previously issued Standards:  
-GB/T 5237.4 -2000, GB 5237.4 -2004  
 
 
 
 - 4 -           GB 5237.4 - 200X  
Wrought aluminium alloy extruded profiles for architecture  
 
Part 4: Powder coat ing profiles  
 
 
1 Scope  
This Standard sets the requirements for the testing methods, inspection rules, packaging, marking, 
transportation, storage and content of contracts (or orders) of powder electrostatic spray -painted 
extruded aluminium alloy profiles for architecture.  
 
This Part applies to aluminium alloy extruded profiles coated with thermosetting organic polymer 
powder for architecture (hereafter referred to as powder coating profiles).  
 
Other aluminium alloy materials that carry similar application s and similar surface treatments may 
refer to and adopt the content of this Part.  
 
2 Normative References  
The provisions of the following documents become provisions of this Part after being referenced. 
For dated reference documents, all later amendments ( excluding corrigenda) and versions do not 
apply to this Part; however, the parties to the agreement are encouraged to study whether the latest 
versions of these documents are applicable. For undated reference documents, the latest versions 
apply to this Pa rt. 
 
 
GB/T 228 -2002 Metallic materials – Tensile testing at ambient temperature;  
 
GB/T 1732 Determination of impact resistance of films;  
 
GB/T 1740 Determination of resistance to heat and humidity of paint films.  
 
GB/T 1766 Paints and varnishes – Rating sc hemes of degradation of coats;  
 
GB/T 1865 – 1997 Paints and varnishes – Artificial weathering and exposure to artificial radiation – 
Filtered xenon -arc radiation;  
 
GB/T 3199 Wrought aluminium and aluminium alloy products – Packing, marking, transporting an d 
storing;  
 
GB/T 4957 Non -conductive coatings on non -magnetic basic metals – Measurement of coating 
thickness – Eddy Current;  
 
GB/T 5237.1 Wrought aluminium alloy extruded profiles for architecture - Part 1: Untreated 
profiles;  
 
GB/T 6461 Methods for corro sion testing of metallic and other inorganic coating on metallic 
substrates – Rating of test specimens and manufactured articles subjected to corrosion tests;  
 - 5 - GB/T 6682 Water for analytical laboratory use – specification and test methods;  
 
GB/T 6742 Paint s and varnishes – Bend test (cylindrical mandrel);  
 
GB/T 8013.3 -2007 Anodic oxide coatings and organic polymer coatings on aluminium and its 
alloys – Part 3: Organic polymer coating;  
 
GB/T 9257 Paints and varnishes – Buchholz indentation test;  
 
GB/T 9276 M ethods of exposure to natural weathering of coating;  
 
GB/T 9286 Paints and varnishes – cross -cut test for films;  
 
GB/T 9753 Paints and varnishes – Cupping test;  
 
GB/T 9754 Paints and varnishes – Measurement of specular gloss of non -metallic paint films at 200, 
600 and 850; 
 
GB/T 9761 Paints and varnishes – Visual comparison of the colour of paints;  
 
GB/T 10125 Corrosion tests in artificial atmospheres – salt spray tests;  
 
GB/T 11186.2, Methods for measuring the colour of paint films – Part 2: Colour measure ment;  
 
GB/T 11186.3 Methods for measuring the colour of paint films – Part 3: Calculation of colour 
differences;  
 
GB/T 16585 Rubber, vulcanised – Test method of resistance to artificial weathering (Fluorescent 
UV lamp;  
 
GB/T 20975 (all Parts) Chemical anal ysis methods of aluminium and aluminium alloys.  
 
JC/T 480 Unslaked Lime for architecture.  
3 Terms and definitions  
The terms and definitions set out in GB/T 8013.3 -2007 apply to this Part, as well as the 
following:  
3.1 Coating  
Coating refers to the cover la yer formed after the thermosetting organic polymer powder been 
sprayed and solidified onto the surface of the metallic base.  
3.2 Exposed surfaces  
Exposed surfaces refers to powder coating profiles that have been processed, manufactured and 
mounted onto a b uilding; the surface of a powder coating profiles which can still be seen either 
in an open or shut state.  
3.3 Local thickness  
Measure the anodic oxide coating thickness of any one inspection area on the exposed surface - 6 - of the powder coating profile that i s not larger than 1cm2 several times (not less than 3 times); 
the local thickness is the average value of the measured coating thickness.  
3.4 Minimum local thickness  
The smallest value of the many measured local thickness of the exposed surfaces on the pow der 
coating profiles.  
4 Requirements  
4.1 Product classification  
4.1.1 Alloy grades, states, specifications  
The alloy grades, supply states and specifications of the powder coating profiles should conform 
to the requirements set out in GB 5237.1.  
4.1.2 Ma rkings  
The arrangement of the labelling of powder coating profiles should be in the following order: 
product name, alloy grade, supply state, product specification (product specification consists of 
the product code and cut -length of the powder coating pro file), colour code and serial number of 
this Part. An example of the label is shown below:  
 
If the powder coating profile is made of 6063 aluminium alloy, its supply state is T5, its profile 
code is 421001, its cut -length is 6000mm, and its colour code num ber 3003, then the label 
should be:  
 
 Powder coating profile 6063 -T5 421001x6000 Colour 3003 GB5237.4 -200X  
4.2 Preliminary treatment  
Preliminary treatments of the powder coating profiles should be carried out in accordance with 
the stipulations of Clause 5  of GB/T 8013.3 -2007.  
4.3 Chemical composition, mechanical properties  
The chemical composition and mechanical properties of the powder coating profiles should 
conform to the requirements set out in GB 5237.1.  
4.4 Dimension deviation  
After the coatings been  removed, the dimension deviations of the profiles should conform to the 
requirements set out in GB 5237.1. The installation and use of the powder coating profiles 
should not be affected by dimension deviations caused by the coatings.  
4.5 Coating propertie s 
4.5.1 Gloss  
The 600 gloss value of the coating and its allowable deviations should conform to the 
requirements set out in Table 1.  
 
 - 7 -  
Table 1 -Gloss Units  
Gloss Value Range  Allowable Deviation  
3 ~ 30  ± 5 
31 ~ 70  ± 7 
71 ~ 100  ± 10 
 
4.5.2 Colour and ch romaticism  
The colour of the powder coatings should be primarily identical to the colour sample plate 
agreed between the suppliers and buyers. When using a colorimeter to take measurements, the 
chromaticism between a single colour coating and the colour sa mple plate should be Eab* 1.5, 
and chromaticism among the same batch of powder coating profiles (referred to as the delivery 
batch) should be Eab* 1.5. 
4.5.3 Coating thickness  
4.5.3.1  The minimum local coating thickness on the exposed surfaces should b e at least 40 m.  
Note: due to the complex shape of the extruded profile cross -sections, the coating thickness on 
certain surfaces (such as inner corners, transverse grooves) of the powder coating profiles are 
allowed to be smaller than the specified value s. 
 
4.5.3.2 If paint spraying is required on non -exposed surfaces, then this request should be clearly 
indicated in the contract.  
4.5.4 Indentation hardness  
The indentation resistance of the coating should be at least 80.  
4.5.5 Adherence  
The dry adherence,  wet adherence and boiling water adherence of the coating should all reach 
level 0.  
4.5.6 Impact resistance  
4.5.6.1  No cracking or peeling should occur to the coating after the impact test.  
 
4.5.6.2  If, after consultation, the buyer and supplier decide to use certain coatings with special 
properties but impact resistance is slightly lower, then tiny cracks are permitted to appear on 
such coatings after the impact test; however if adhesive tape is used to carry out further tests, 
then none of the coating sho uld peel away.  
4.5.7 Cupping resistance  
4.5.7.1 No cracking or peeling should occur to the coating after the cupping test.  
 
4.5.7.2  If, after consultation, the buyer and supplier decide to use certain coatings with special 
properties but cupping resistance  is slightly lower, then tiny cracks are permitted to appear on 
such coatings after the cupping test; however if adhesive tape is used to carry out further tests, 
then none of the coating should peel away.  
 - 8 - 4.5.8 Bend resistance  
4.5.8.1  No cracking or peel ing should occur to the coating after the after the bend test.  
 
4.5.8.2  If, after consultation, the buyer and supplier decide to use certain coatings with special 
properties but bend resistance is slightly lower, then tiny cracks are permitted to appear on  such 
coatings after the bend test; however if adhesive tape is used to carry out further tests, then none 
of the coating should peel away.  
4.5.9 Wear resistance  
After the Falling -sand Test, the abrasion coefficient should be at least 0.8L/m.  
4.5.10 Boili ng water resistance  
After the Boiling Water test, carry out a visual inspection to check the tested coating surface. 
Coating peeling or wrinkling should not occur, yet visible, widespread, very tiny bubbles are 
allowed, and small changes affecting the coat ing colour are permitted.  
4.5.11 Hydrochloric acid corrosion resistance  
After the hydrochloric acid corrosion resistance test, carry out a visual inspection to check the 
tested coating surface. No bubbles should appear on the surface or any other noticeabl e changes.  
4.5.12 Mortar resistance  
After the mortar resistance test, carry out a visual inspection to check the tested coating surface. 
There should be no peeling of the coating and no other noticeable changes should occur.  
4.5.13 Solvent resistance  
The r esult of solvent resistance test should be appropriately as Grade 3 or Grade 4.  
4.5.14 Detergent resistance  
After the detergent resistance test, carry out a visual inspection to check the tested coating 
surface. No bubbles or peeling should appear and no o ther noticeable changes should occur.  
4.5.15 Salt spray corrosion resistance  
After 1000 hours of the acetic acid salt -spray test, carry out a visual inspection to check the 
tested coating surface. No bubbles, peeling or any other noticeable changes should occur under 
either side of the coating cut line.  
4.5.16 heat and humidity resistance  
After 1000 hours of the heat -humidity test, carry out a visual inspection to check the tested 
coating surface. No bubbles, peeling or any other noticeable changes should o ccur.  
4.5.17 Weatherability  
4.5.17.1 Accelerated weatherability  
Weatherability should be divided into two classes on the basis of test duration and test results of 
irradiation with a xenon lamp for the artificial accelerated ageing test, please see Table 2 . The 
weatherability classification should be decided by the buyers and clearly indicated in the 
contract; if it is not indicated in the contract, then the profiles should be supplied as class I.  - 9 -  
Table 2  
Test Results a Weatherability 
Class  Test Duration  
Colour Change 
Degree  Gloss Retention b 
I 1000 hours  Eab*  5 > 50%  
II 1000 hours  Eab*  2.5 > 90%  
a The test duration and test results of brightly coloured coatings such 
as black, yellow and orange should be decided through consultation 
between the buyer and supplier, and clearly indicated in the contract.  
b The gloss retention is determined as the percentage difference 
between the gloss value after testing and the gloss value before testing.  
 
4.5.17.2 Natural weatherability  
If the buyer has request s regarding the natural weatherability of the powder coatings, then the 
test conditions and the acceptance standard should be decided through consultations between 
the supplier and buyer, and should be clearly indicated in the contract.  
4.5.18 Others  
4.5.1 8.1 If the buyer has special requests regarding impact resistance, wear resistance, boiling 
water resistance, salt spray corrosion resistance, heat -humidity resistance, and the weatherability 
of the powder coatings, both the supplier and the buyer may refe r to the requirements set out in 
GB/T 8013.3 -2007 and decide upon the property requirements through consultation. The agreed 
testing requirements should be clearly indicated in the purchase contract.  
 
4.5.18.2  If the buyer requests other properties of the powder coatings, the supplier and the buyer 
should refer to the requirements set out in GB/T 8013.3 -2007 and come to a decision through 
consultation.  
4.6 Appearance quality  
The coatings on the exposed surfaces of the powder coating profiles should be smoo th, even, 
and no faults that might affect the use of the profiles, such as flow marks, wrinkles, bubbling 
and coating cracking are permitted. However a slight orange -peel phenomenon is permitted and 
the allowable degree should be decided through consultati ons between the buyer and supplier.  
5 Testing methods  
5.1 Chemical composition  
The reference analysis of chemical composition should be carried out in accordance with the 
methods set out in GB/T 20957.  
5.2 Chemical properties  
The mechanical properties refe rence test should be carried out in accordance with the methods 
set out in GB/T 228 -2002. The elongation percentage after fracture should be measured in 
accordance with the requirements set out in Section 11.1 of GB/T 228 -2002.  - 10 - 5.3 Dimension deviation  
Dime nsion deviation should be measured in accordance with the methods set out in GB 5237.1.  
5.4 Coating properties  
5.4.1 Gloss  
According to the procedures in GB/T 9754, use a gloss metre to determine the gloss at a 600 
incident angle.  
5.4.2 Colour and chromat icism  
5.4.2.1 Visual inspection method  
Carry out test in accordance with the rules set out in GB/T 9761.  
5.4.2.2 Instrumental method  
Use a colorimeter to perform the single colour coating reference test. Take the measurement 
according to the methods set ou t in GB/T 11186.2, and GB/T 11186.3.  
5.4.3 Coating thickness  
5.4.3.1 The coating thickness measurement should be taken in accordance with the procedures 
set out in GB/T 4957.  
 
5.4.3.2  Choose at least 5 suitable measuring spots (each test spot should be ab out 1cm2) to 
measure the thickness of the inspection coating, then record 3 ~ 5 readings of each measuring 
spot. The average value of the recorded readings is regarded as the measured result of the 
measuring spot local thickness.  
5.4.4 Indentation hardness  of the coating  
This measurement should be carried out in accordance with the measure procedures specified in 
GB/T 9275.  
5.4.5 Adherence  
5.4.5.1 Dry adherence  
5.4.4.1.1  Draw squares according to the procedures specified in GB/T 9286. The interval 
between each square should be 2mm.  
 
5.4.5.1.2  Cover the square drawing coating with adhesive tape1). The adhesive force of the tape 
should be greater than 10N/25mm. Press the tape down tightly to remove any air from 
underneath the tape, then pull the tape off quic kly at a vertical angle from the coating surface. 
Carry out the evaluation according to GB/T 9286.  
5.4.5.2 Wet adherence  
According to the stipulations of 5.4.5.1.1 draw squares on the sample using third grade water as 
specified in GB/T 6682 with a temperat ure of 380C± 50C. Soak the sample for 24 hours. 
Remove the sample and wipe it dry. As according to 5.4.5.1.2, carry out the testing and 
evaluation within 5 minutes.  - 11 - 5.4.5.3 Boiling water adherence  
5.4.5.3.1 Draw squares on the sample according to the stipu lation set out in 5.4.5.1.1.  
 
5.4.5.3.2  Pour around 80mm of third grade water into a beaker as specified in GB/T 6682, and 
then place 2 - 3 pieces of clean broken porcelain into the beaker. Heat the water from the 
bottom of the beaker until the water boils . 
 
5.4.5.3.3  Hang the sample in the water and allow to boil for 20 minutes. The sample should be 
10mm under the surface of the water, without touching the bottom of the beaker. During the test, 
the water temperature should be maintained at least at 950C, and whenever necessary add boiled 
third grade water as specified in GB/T 6682 into the beaker to maintain the depth of the water at 
least at 80mm.  
 
5.4.5.3.4  Remove the sample and wipe it dry. As according to 5.4.5.1.2, carry out the testing and 
evaluation within 5 minutes.  
5.4.6 Impact resistance  
5.4.6.1  Use a punch ball of 16mm± 0.3mm diameter to carry out the drop impact test, in 
accordance with the test procedures specified in GB/T 1732: place an impact hammer (1000g± 
1g) at a suitable height and allow i t free fall, then drop the hammer directly onto the non -coated 
surface of the standard sample plate, resulting in an indentation of depth of 2.5mm± 0.3mm. 
Carry out a visual inspection on the tested coating surface to check for changes made to the 
coating.   
 
5.4.6.2  With regard to coatings with special properties but with slightly lower impact resistance, 
immediately cover the impact tested coating surface with a piece of adhesive tape1), the 
adherence force of which should be greater than 10N/25mm. Press t he tape down tightly to 
remove any air from underneath the tape, then quickly pull the tape off at a vertical angle from 
the coating surface. Carry out a visual inspection to check whether any coating peels off from 
the coating surface.  
 
(1) The suitable a dhesive tapes on the market are Scotch Premium Cellophane tape 610 or 
Permacel P -99 adhesive tape. We list these products here for information for the convenience of 
those people using this Part of the standard; however this does not mean that the products  will 
be accepted.)  
5.4.7 Cupping resistance  
5.4.7.1  According to the procedures set out in GB/T 9753, use a standard sample board to carry 
out the test, and press down to a depth of 5mm.  
 
5.4.7.2 With regard to coatings with special properties but with sl ightly lower cupping 
resistance, immediately cover the cupping tested coating surface with a piece of adhesive tape1), 
the adherence force of which should be greater than 10N/25mm. Press the tape down tightly to 
remove any air from underneath the tape, the n quickly pull the tape off at a vertical angle from 
the coating surface. Carry out a visual inspection to check whether any coating peels off from 
the coating surface.  
5.4.8  Bend resistance  
5.4.8.1 According to the procedures set out in GB/T 6742, use a s tandard sample board to carry - 12 - out the test.  
 
5.4.8.2  With regard to coatings with special properties but with slightly lower bend resistance, 
immediately cover the cupping tested coating surface with a piece of adhesive tape1), the 
adherence force of which  should be greater than 10N/25mm. Press the tape down tightly to 
remove any air from underneath the tape, then quickly pull the tape off at a vertical angle from 
the coating surface. Carry out a visual inspection to check whether any coating peels off from  
the coating surface.  
5.4.9 Wear resistance  
Carry out wear resistance test in accordance with the procedures specified in Appendix A .  
 
5.4.10 Boiling water resistance  
 
5.4.10.1  Pour around 80mm of third grade water into a beaker as specified in GB/T 6682,  and 
then place 2 - 3 pieces of clean broken porcelain into the beaker. Heat the water from the 
bottom of the beaker until the water boils  
 
5.4.10.2  Hang the sample in the water and allow it to boil for 20 minutes. The sample should be 
10mm under the surfa ce of the water, without touching the bottom of the beaker. During the test, 
the water temperature should be maintained at least at 950C, and whenever necessary add boiled 
third grade water as specified in GB/T 6682 into the beaker to maintain the depth of  the water at 
least at 80mm.  
 
5.4.10.3 Remove the sample and wipe it dry. Perform a visual inspection to check the boiling 
water tested coating surface (the surrounding parts of the sample are not included).  
5.4.11 Hydrochloric acid corrosion resistance  
Use chemical hy drochloric acid (1.19g/ml) and third grade water as specified in GB/T 6682 to 
mix the hydrochloric acid test solution (hydrochloric acid and water as 1:9). Drip 10 drops of 
this hydrochloric acid test solution onto the coating surface of the sample, then cover with a 
watch glass and leave it in an environmental temperature of 180C ~ 270C for 15 minutes. Rinse 
clean under tap water, air dry, then perform a visual investigation to check the tested coating 
surface.  
5.4.12 Mortar resistance  
5.4.12.1  Take 75g l ime powder as specified in JC/T 480 and 225g Standard Sand as specified in 
section A.5.2 of Appendix A, and add into about 100g third grade water as specified in GB/T 
6682 to form the lime and sand paste mortar mix.  
 
5.4.12.2 Place the paste mortar onto t he surface of the sample, pile up to a diameter of 15mm 
and thickness of 6mm cylinder. Leave in an environment with a temperature of 380C± 30C and 
relative humidity of 95%± 5% for 24 hours.  
 
5.4.12.3  Remove the paste mortar from the sample and, using a we t cloth, clean the residue off 
the surface and allow to air dry. Perform a visual investigation to check the tested coating 
surface.  - 13 - 5.4.13 Solvent resistance  
The solvent resistance test should be carried out in accordance with the procedures specified in 
Appendix B.  
5.4.14 Detergent resistance  
5.4.14.1  Use detergent (for composition see Table 3) and third grade water as specified in GB/T 
6682 to mix up the detergent test solution to a concentration of 30g/L. Soak at least 2 samples in 
the detergent test s olution at a temperature of 380C for 72 hours, then remove the sample and 
wipe it dry. Perform a visual inspection to check the tested coating surface.  
 
Table 3  
Composition  Content (Weight) %  
Tetrasodium Pyrophosphate  53 
Sodium Sulphate Anhydyous  19 
Sodium Linear alkylarylsulfonate  20 
Sodium Metasillicate Hydrated  7 
Sodium Carbonate Anhydrous  1 
Total  100 
 
5.4.14.2  Immediately cover the tested coating surface with a piece of adhesive tape. The 
adhesive force of the tape should be greater than 10N/25mm . Press the tape down tightly to 
remove any air from underneath the tape, then pull the tape off quickly at a vertical angle from 
the coating surface. Perform a visual inspection to check the tested coating surface.  
5.4.15 Salt spray corrosion resistance  
On a piece of sample,, cut two cross lines along the diagonal as deep as the metallic base - the 
line segment should not run through the opposite corner and the distances from each end point 
of the line segments to the corresponding opposite corner should b e the same. Next, carry out 
the acetic acid salt spray test according to the test procedures specified in GB/T 10125. When 
the specified test duration is completed, perform a visual inspection to check coating surface 
and check the unidirectional infiltrat ion degree underneath of the coating.  
5.4.16 Heat -humidity resistance  
According to the procedures specified in GB/T 1740, carry out the heat -humidity resistance test, 
test temperature should be 470C± 10C. 
5.4.17 Weatherability  
5.4.17.1 Accelerated weathera bility  
Carry out xenon lamp accelerated weatherability test according to method 1 specified in GB/T 
1865 -1997. The gloss value measuring procedure should be performed according to GB/T 9754, 
and evaluations for chalking degree and colour change degree shou ld be taken according to the 
specifications of GB/T 1766.  - 14 - 5.4.17.2 Natural weatherability  
Carry out the test according to the procedures specified in GB/T 9276.  
Note: among the atmospheric corrosion test stations in China, the only test station with 
atmosp heric conditions close to the specified Florida Atmospheric set out in international 
standards is the Qionghai Exposure Test Station.  
5.4.18 Others  
Tests for other properties should be carried out according to test methods specified in GB/T 
8013.3 – 2007, or according to the method agreed between the suppliers and the buyers.  
5.5 Appearance quality  
The examination for appearance quality should be carried out under diffuse sunlight (diffuse 
sunlight refers to after 3 hours after sunrise to 3 hours before sun set) according to GB/T 9761. 
The required luminance level for artificial illumination should be above 1000lx and the light 
source should be a D65 standard light source. The background should be matt black or grey; a 
coloured background cannot be used. The viewing distance should be 3m, and the viewing angle 
should be 900. 
6 Inspection rules  
6.1 Examination, checking and acceptance  
6.1.1  Examinations to ensure that the quality of the powder coating profiles are in line with the 
requirements set out in this P art (or purchase contract) should be carried out by the suppliers, 
who should also complete a quality certificate.  
 
6.1.2  Buyers may carry out examinations that are specified in this Part regarding the powder 
coating profiles they receive. If the results o f the examinations do not conform to the 
requirements set out in this Part or the purchase contract, the buyer can submit a disagreement 
in writing to the supplier, after which the supplier and the buyer should come to an agreement 
through consultation. If  the disagreement is related to appearance quality and dimension 
deviation, the buyer should submit the problems within one month of the date on which they 
received the powder coating profiles; if the disagreement relates to other properties, then the 
buye r can submit the problems within three month of the date on which they receive the powder 
coating profiles. If the problem must be settled through further testing, sampling should be 
provided by the suppliers and the settling should be carried out mutually  by the supplier and 
buyer.  
6.2 Batch approval  
Powder coating profiles should be submitted for approval and acceptance in batches. Powder 
coating profiles with the same alloy grade, same supply states, same specifications and same 
colour constitute a batch . The quantity of profiles in each batch of powder coating profiles is 
unrestricted.  
6.3 Inspection item  
Inspections for chemical composition, mechanical properties, dimension deviation, gloss, colour 
and chromaticism, coating thickness, indentation hardne ss, adherence, impact resistance, as well 
as appearance quality, should be carried out on every batch of powder coating profiles. 
Inspections on other properties are not usually carried out (the suppliers carries out these types - 15 - of inspections at least onc e in every three years), but the supplier should ensure these properties 
are in line with the requirements set out in this Part. If the buyer requests an inspection be 
carried out on these properties, then such requests should be clearly indicated in the c ontract.  
6.4 Sampling  
Powder coating profile sampling procedures should be carried out in accordance with the 
stipulations of Table 4.  
 
Table 4  
Test Item  Sampling Rules  Requested 
Clause 
Number  The Clause 
Number of 
Test 
Method  
Chemical composition, 
mechani cs properties, 
dimension deviation,  Carry out according to the stipulations of GB 
5237.1.  4.3 
4.4 5.1 
5.2 
5.3 
Coating colour and 
chromaticism  One by one inspection method.  4.5.2  
4.6 5.4.2  
5.5 
Coating thickness  Sampling procedure to be carried out in 
accordance with specifications of Table 5.  4.5.3  5.4.3  
Impact resistance, 
cupping resistance, 
bend resistance  Make two standard sample boards per each 
inspection item.  
Method for making standard sample board: 
choose two pieces pure aluminium sample 
boards, on e with state of H24, another with 
state of H14, both boards with the same 
dimension as 150mm x 75mm x 1.0mm, 
adopt the same technology and same 
production line as the batches of profiles the 
samples are representing to have the paint 
sprayed (the coating t hickness should be 
appropriately kept in the range of 60 m ~ 80 
m), solidified, after this leave the samples 
for 24 hours.  4.5.6  
4.5.7  
4.5.8  5.4.6  
5.4.7  
5.4.8  
Gloss, indentation 
hardness, adherence, 
wear resistance, boiling 
water resistance, 
hydrochloric acid 
corrosion resistance, 
mortar resistance, 
solvent r esistance, 
detergent resistance, 
salt spray corrosion 
resistance, heat 
humidity resistance, 
weatherability of the 
coating  Take 2 profiles per inspection item from each 
batch of powder coating profiles. After the 
coating has solidified and left for 24 hours , 
cut one sample from each of the two powder 
coating profiles.  4.5.1, 4.5.4, 
4.5.5, 4.5.9, 
4.5.10, 
4.5.11, 
4.5.12, 
4.5.13,  
4.5.14, 
4.5.15,  
4.5.16, 
4.5.17  5.4.1, 5.4.4, 
5.4.5, 5.4.9, 
5.4.10, 
5.4.11, 
5.4.12, 
5.4.13, 
5.4.14, 
5.4.15, 
5.4.16, 
5.4.17,  - 16 - Others  To be carried out according to GB/T 8013.3 -
2007 or according to the agreement between 
the buyer and the supplier.  4.5.18  5.4.18  
 
6.5 Determination of the inspection results  
6.5.1  If the inspection for chemical composition does not meet the required standa rd, then the 
batch is deemed not qualified.  
 
6.5.2  Inspection for mechanics properties: if any one of the samples does not meet the required 
standard, re -sampled should be carried out using double the original number of test samples 
from this batch of prof iles (include original unqualified sample) and a repeat test should be 
carried out on these samples. If the repeated test results all qualify, then this batch of powder 
coating profiles is deemed qualified. If any of the repeated test results is still not up to the 
required standard, then this batch is deemed not qualified.  
 
6.5.3  If the colour, chromaticism or appearance quality of the coating does not meet the required 
standard, then this single piece is deemed not qualified.  
 
6.5.4  If dimension deviation  does not meet the required standard, then this batch of powder 
coating profiles is deemed not qualified. However, individual inspection is permitted and 
qualified powder coating profiles should be delivered.  
 
6.5.5 If the number of unqualified coating thi ckness exceeds the specified allowable unqualified 
upper limit numbers shown in Table 5, then this batch of profiles is deemed not qualified. 
However, individual inspection is permitted and qualified powder coating profiles should be 
delivered.  
 
Table 5  
Quantity Range in Each 
Batch  Random 
Sampling  Upper Limit of 
Unqualified 
Items  
1 ~ 10  Entire Batch  0 
11 ~ 200  10 1 
201 ~ 300  15 1 
301 ~ 500  20 2 
501 ~ 800  30 3 
Over 800  40 4 
 
6.5.6  The solvent resistance results should only be considered as references and should not be 
considered as evidence of whether the coating quality qualifies or not.  
 
6.5.7  If any one of the test results of other properties of the coating fails to qualify, then the 
whole batch of powder coating profiles is deemed unqualified.  - 17 - 7 Ma rkings, packaging, transportation, storage  
7.1 The label (or quality certificate) on the qualified powder coating profiles should contain the 
following information:  
 
a) the name and address of the supplier;  
b) the examination stamp from department of quality con trol of the supplier;  
c) alloy grade and state;  
d) the name and specification of the profile;  
e) production date or batch number;  
f) the weatherability grade, the colour or profile serial number;  
g) serial number of this Part;  
h) production license number and QS mark.  
 
7.2 The packaging symbols of powder coating profiles should meet the requirements of GB/T 
3199.  
 
7.3 The profiles should be bundled up and packed in paper, and the exposed surfaces of the 
profiles should be protected with paper padding or bubble wrap.  
 
7.4 The transportation and storage of the powder coating profiles should meet the requirements 
specified in GB/T 3199.  
7.5 Quality certificate  
A copy of the quality certificate should be enclosed with each batch of power coating profiles, 
on which the following s hould be clearly indicated:  
a) name of the supplier;  
b) the name and specification of the powder coating profiles;  
c) alloy grade and state;  
d) batch number or production date;  
e) weight or quantity;  
f) every analysed inspection result and the examination stamp from departm ent of quality 
control of supplier;  
g) the serial number of this Part;  
h) production license number;  
i) leaving factory date (or package date).  
8 The contents of the contract (or order list)  
The contract (or order list) to purchase listed materials in this Part sho uld contain the following 
information:  
a) product names  
b) alloy grades,  
c) supply states;  
d) profiles specifications;  
e) dimension and its allowable deviations accuracy grades;  
f) coating glossiness,  
g) colour and the colour number;  
h) weight or quantity;  
i) serial number of this Part;  
j) other requests.  - 18 - Appendix A  
 
(Normative Annex)  
 
Falling Sand Test Procedure  
A.1 Scope  
This appendix specifies the falling sand test procedures for measuring the wear resistance of 
powder coatings.  
 
This appendix applies to the wear resistance measurem ent of the powder coating on the base of 
aluminium alloy profiles.  
A.2 Procedure summary  
Allow the standard sand to fall freely through the conduit from a specified height, scouring the 
coating on the sample surface, until the sample is worn down to show t he base. Record the 
quantity of standard sand used per unit coating thickness to determine the wear resistance of this 
coating.  
A.3 Test sample  
The dimension of the test sample is 150mm x 75mm; the sample should be cut from the exposed 
surfaces of the prod ucts which have accepted the test. If the products which have accepted the 
test do not have suitable exposed surfaces to cut the required dimension samples, then a board 
sample with the same alloy grade, same production process and same state as the produc ts 
which have accepted the test should be chosen, and should endure the same surface treatments 
as products which have accepted the test to represent the batch of products taking the inspection.  
A.4 Test environment  
A.4.1  The test should be carried out in room temperature, with a relative humidity about 80% or 
less. 
 
A.4.2  During the test process, the test should be sheltered from the wind.  
A.5 Instruments and abrasion testing materials  
A.5.1  The demonstration of the test instrument structure of the test as  below:  - 19 -  
A.5.2  Use Standard Sand as the abrasion material of the test (the content of SiO 2 in the sand  
should be greater than 96%, ignition loss should not exceed 0.40%, the content of soil 
(including soluble salt) should not exceed 0.20%), its grain size  should be in line with the 
requirements in Table A.1.  
Table A.1  
Hole dimension of the  
square hole screen, mm  Total screen residue  
0.65 < 3 
0.40 40 ± 5  
0.25 > 94 
 
A.6 Test procedures  
A.6.1  Draw three circular areas with a diameter of 25mm on each sampl e and, according to the 
procedures specified in Section 5.4.3 of this Part, measure and record the coating thickness of 
each area.  
 
A.6.2  Fix the sample to the sample support seat and adjust the sample until one of the circular 
areas' centres is exactly un derneath the conduit. The test surface and the conduit should be at a 
450 angle. Pour into the hopper the pre -measured volume of standard sand, and allow the sand 
to fall freely; the sand flow speed should be controlled as: the flow out sand quantity shoul d be 
2L per 16 seconds - 18 seconds. Repeat the sand falling until a 4mm diameter circle sample 
shows its metallic base.  
 
A.6.3  Repeat the wear out the rest of the other two circular areas on the sample.  
A.7 Test results  
A.7.1  Use the following formula to calculate the abrasion coefficient ( f) of the three circular 
areas on the sample:  
 
f = V / h 0        .............................................................(A.1)  
 
in the formula:  
- 20 - f – abrasion coefficient, unit expressed as litre per micron (L/m)  
V – the used volume of the test wear material, unit expressed as litre (L);  
h0 – coating thickness, unit expressed as micron (m).  
 
A.7.2 The average value of the three abrasion coefficients should be determined as the test 
result, accuracy to 0.1L/m.  
 
 
 - 21 - Appendix B  
 
(Normative Annex)  
Solvent Resistance Test  
B.1 Scope  
This appendix specifies the solvent resistance test procedures of powder coatings.  
 
This appendix applies to the solvent resistance measurement of the powder coating on the bases 
of aluminium all oy profiles.  
B.2 Test procedures  
Place an absorbent cotton swab in xylene liquid until it is properly soaked. Then use the 
absorbent cotton along the same straight line path and with a speed of one return per second 
wipe back and wipe the sample surfaces c oating 30 times. Move the cotton swab away, rinse the 
sample clean under tap water, wipe dry, leave it in room temperature for 2 hours, then check the 
coating surfaces.  
B.3 The test results shown:  
Grade 1: the coating colour goes darker and the coating goe s soft;  
Grade 2: the coating colour becomes very dark and a finger nail can cause scratch marks;  
Grade 3: the gloss of the coating changes (glossiness becomes lower than gloss unit 5);  
Grade 4: no noticeable changes to the coating; when a finger nail is sc ratched over the coating, 
no scratch marks appear.  
 
 
The People's Republic of China  
National Standard  
Wrought aluminium alloy extruded profiles for architecture  
Part 4: Powder coating profiles  
GB 5237.4 – 200X  
 
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