This standard is applicable to the determination of the resistance of paint films on wooden furniture and other wooden furniture parts to temperature differences. GB 4893.7-1985 Determination of resistance of paint films on furniture surfaces to temperature differences GB4893.7-1985 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Furniture-Assessment of surface resistance to alternation of heat and cold This standard is applicable to the determination of the resistance to alternation of heat and cold of the paint film on the surface of wooden furniture and other wooden furniture parts. Materials and instruments and equipment
1.1 The temperature of the constant temperature and humidity chamber is higher than 60℃, and the relative humidity is 98%~99%. 1.2 The temperature of the low-temperature refrigerator is lower than -40℃.
1.3 The division value of the balance is 0.1g.
1.4 Electric furnace.
1.5 Four-fold magnifying glass.
1.6 Flat bristle brush.
1.7 Paraffin wax.
1.8 Rosin.
2 The sample
The specification is 250mm×200mm.
UDC 684.4 : 667
GB4893.7—85
2.2 The number of samples is four, three for testing and the other for comparison. 2.3 The surface of the sample should be flat, and the paint film should be free of defects such as scratches and bubbles. The sample should be sawed before painting to avoid affecting the fastness of the paint film. 2.4 The sample should be stored for at least 10 days after painting and completely dry before testing. A test report should be attached when sending samples, including the name of the paint, a brief painting process, production time, etc. 2.5
3 Test conditions
3.1 The test room temperature is 20±2℃, the relative humidity is 60%~70%, and the sample is stable in the test room for at least 24h. 3.2 The test temperature, humidity and cycle are based on the product standard or the agreement between the supply and demand parties. It is recommended that the temperature and humidity be 40±2℃, the relative humidity be 98%～99% and -20±2℃, and the number of cycles be multiples of 3, such as 3, 6, 9, 12, 15, 18 weeks, etc. bZxz.net
4 Test steps
4.1 Seal the periphery and back of the test piece with a paraffin-rosin mixture of 1:1. 4.2 Each cycle during the test consists of two stages: in the first stage, the sample is placed in a constant temperature and humidity chamber with a specified temperature and humidity for 1 hour, and in the second stage, the sample is moved from the constant temperature and humidity chamber to a low-temperature refrigerator with a specified temperature for 1 hour, and the time for the sample to be transferred from one chamber to another is required to be no more than 2 minutes.
4.3 After every three cycles, the sample is placed at a temperature of 20±2℃ and a relative humidity of 60%～70% for 18 hours, and then inspected.
Issued by the National Bureau of Standards on February 1, 1985
Implemented on April 10, 1985
5 Evaluation of test results and test report
GB 4893.7-85
Exclude the range of 20mm from the edge of the sample during inspection, and then observe the paint film surface in the middle part with a four-fold magnifying glass. If there are cracks, 5.1
bubbling, obvious loss of gloss and discoloration, this sample will be evaluated as unqualified (regardless of the shape, size and number of defects). Three inspectors must evaluate each sample separately, and take the majority of the same values ​​as the evaluation results. 5.2
The three samples should be evaluated separately, and the evaluation values ​​of two consistent samples shall be taken as the final test results. 5.3
5.4 "The test report shall include the following contents:
test date,
the name of the coating material of the sample and a brief coating process, the storage time after the sample coating is completed,
the test time and test results, etc.
Additional remarks:
This standard is proposed by the Ministry of Light Industry of the People's Republic of China and is technically managed by the Shanghai Furniture Research Institute. This standard is drafted by the Shanghai Furniture Research Institute. The main drafter of this standard is Yang Changkang.
This standard is formulated with reference to the Soviet standard 『OCT19720-74 "Determination of the resistance to cold and hot temperature difference of color paint coatings".588
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