EVALUATION OF THE QUALITY OF THE PAINTED FILMS
Currently, Mega Vietnam New Materials Research and Development Center is evaluating the mechanical and mechanical parameters of the completely dry paint film after construction based on Vietnamese (TCVN) and international standards (ASTM) and giving reliable results. The paint film evaluation criteria include magnetic thickness, gloss, cross-cut grip, impact strength, pencil hardness, and flexural strength.
1. Determination of magnetic thickness
- Determine the thickness of the dry paint film based on the standard TCVN 9406:2012.
- How to proceed:
+ Turn on the meter, select magnetic mode (Fe) or non-magnetic mode (NFe), and calibrate to 0.
+ Place the standard plate with a thickness of 50 µm on the unpainted specimen and calibrate the instrument to 50 µm, press zero.
+ Measure the specimen to be determined, and read the results recorded on the machine.
Figure 1: BGD 542/2
2. Determination of gloss
- Determination of gloss of dry film based on ASTM D523-8.
- How to proceed:
The sample to be measured must be cleaned of dust and dirt.
+ Calibration of gloss measurement equipment.
+ Place the device on the surface of the paint film, and press the button to read the results, the results will be displayed on the screen at all 3 angles: 20⁰, 60⁰, 85⁰
Figure 2: Gloss meter 516/3
3. Determination of cross-cut grip
- Determination of cross-cut adhesion of paint film according to standard TCVN 2097: 2015.
- How to proceed:
Place the sample on a hard, flat surface. Using the force of making 6 cuts on the screen, the distance between the cuts is 1-2 mm depending on the thickness of the coating and the type of substrate.
+ Repeat the above operation, make 6 perpendicular cuts, and cross the original cut 90o.
Place the tape over the cut, gently rub the tape and remove the tape by pulling the other end for 0.5-1 second, as close to a 60° angle as possible.
+ Visually inspect the cut surface or use a magnifying glass under good light. There are 6 different adhesion levels depending on the peeling ability of the paint film.
- In addition to the Cross cut adhesion evaluation method, Megarad also evaluates the Pull-off adhesion for the results displayed in MPa units (mainly used for paints with high adhesion such as PU2K paint, anti-fire paint, etc.)
4. Determination of impact resistance
- Determination of impact resistance of paint film based on standard TCVN 2100-2:2007.
- How to proceed:
+ Install the impact carrier, and place the sample plate to be evaluated in the anvil position.
+ Pull the load to a height at which failure is expected to occur, and release the bag so it falls on the impact bearing.
+ Remove the test plate from the device and observe the impact area for cracks in the paint film.
+ Record the average height (in cm) and the weight of the load (kg).
Figure 3: Paint film impact resistance measuring device.
5. Determination of pencil hardness
- Determination of pencil hardness of paint film based on ASTM D3363.
- How to proceed:
+ Clean the sample surface to be measured and place the sample on a flat surface.
+ Sharpen the pencil and sharpen it with fine sandpaper adjusted so that the length of the lead is 5-6 mm from the wood.
+ Place the pencil in the drill hole on the car at an angle of 450 to the vertical direction of the pencil hole. Move the cart (about 6.5 mm).
+ The process starts with the hardest pencil and decreases the hardness level until the pencil does not scratch the film.
Figure 4: Pencil hardness tester
6. Determination of flexural strength
- Evaluation of flexural strength of paint film based on TCVN 2099:2013 standard.
- How to proceed:
+ Clamp one corner of the sample to be evaluated to the test device and use pliers to bend the surface of the test piece (the paint film is facing out).
+ Evaluation of flexural strength of shafts with sizes from small to large.
+ The flexural strength of the paint film is determined at the axis at which the coating does not crack or separate from the substrate.
Above are some basic introductions about the quality assessment of paint film at Mega Vietnam New Materials Research and Development Center. We receive an evaluation of the above criteria and send back reliable results, comments, and sweeping conclusions to customers before an official quality appraisal by the authorities.
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Contact
Office address: Floor 2-A2-IA20, Nam Thang Long Urban Area, Pham Van Dong Street,
Dong Ngac Ward, Bac Tu Liem District, Hanoi City, Vietnam
Research Center: Nhue hamlet - Kim Chung village - Dong Anh district - Hanoi - Viet Nam
Website: megaradcenter.com
Tel/Fax: (+84) 24 375 89089 / (+84) 24 375 89098
Email: contact@megavietnam.vn
