Orange peel is a particular type of end that can develop on a painted and cast surface, even a screen protector. Its texture resembles the orange peel surface. Spark paint sprayed on a smooth surface (such as a car's body) should also dry to a smooth surface. However, various factors can cause it to dry up into a wavy surface that resembles the orange peel texture. The citrus peel phenomenon can then be smoothed with ultra-fine sandpaper, but can be prevented altogether by altering painting techniques or materials used. Orange peels are usually the result of incorrectly painted techniques, and this is due to the rapid evaporation of a thinner and less precise spray gun arrangement (eg, low air pressure or wrong nozzle), spray paint on an angle other than perpendicular, or applying excess paint.
In some situations, such as interior house paint, orange peel texture is desirable. In this case, texture paint is generally applied with a spray gun. The texture is then painted with the appropriate color. When painting walls, orange peel can also develop by using a roller with too little paint or paint that is too thick and the surface to dry before the texture can rise.
Video Orange peel (effect)
Measurement
The instrument used to measure orange peel simulates visual perception. Like our eyes, the instrument optically scans the wavy/dark pattern of waves. Two types of instruments are available for measuring texture or surface waviness:
Orange peel color
Orange peeler peelers use a laser point light source to illuminate the specimen at an angle of 60 ° and use a detector to measure the intensity of reflected light at the same angle but opposite. The instrument is rolled on the surface and measuring point by point of the surface optical profile along the specified distance. The instrument analyzes the structure according to its size. To simulate the resolution of the human eye at various distances, the measurement signal is divided into several ranges using the mathematical filter function:
- Wa 0.1..... 0.3 mm wavelength
- Wb 0.3........ Wavelength 1 mm
- Wc 1............ Wavelength 3 mm
- Wd 3......... Wavelength 10 mm
- Our 10....... Wavelength 30 mm
- SW 0.3..... Wavelength 1.2 mm
- LW 1,2....... Wavelength 12 mm
Simple Measurement Diagram
Structures smaller than 0.1 mm also affect visual perception, therefore the instrument uses a CCD camera to measure the diffused light caused by this delicate structure. This parameter is referred to as "ignorance".
Dull and Wa values ​​for We form a "spectrum of structures". This allows a detailed analysis of the orange peel and its effect factors, which become the material or application parameters. Examples of "spectrum structures"
Detailed information from the structural spectrum as well as LW and SW become the basis for correlating to specific scale and to DOI as described in ASTM E430.
Stepped step deflectometer
Phase stepped deflectometry (PSD) is a white light optical technique that uses a fringe pattern projected from a high definition screen to capture reflected images from a pattern using a high definition camera. A sinusoidal waveform such as a surface ridge that allows relative coordinate points of light source points to be quantified as it is proportional to the spatial phase of the sinusoidal pattern waveform. Using a standard technique known as "stepping step" accurate measurements of any point on the surface can be done by quantifying the corresponding point per pixel on the camera.
Using the known geometric relationship between the screen, the object surface and the camera, the reflected light rays from the surface can be modeled spatially to calculate the normal direction at each point of the surface to allow the profile at that point to be obtained. By displaying a sinusoidal waveform in both horizontal and vertical directions the surface slope can be determined in both orthogonal directions.
By differentiating the measurement data the curvature field can be calculated allowing accurate characterization of the surface profile. To simulate the resolution of the human eye at various distances, a special band filtering filter is applied to the curvature data that separates the structure data by size:
- Ka 0.1..... 0.3 mm wavelength
- Kb 0.3........ Wavelength 1 mm
- Kc 1............ Wavelength 3 mm
- Kd 3......... Wavelength 10 mm
- To 10....... Wavelength 30 mm
- Ks 0.3..... Wavelength 1.2 mm
- Cl 1.2....... Wavelength 12 mm
This information is then converted into texture data (waviness) by applying a standard equation. Unlike other curvature and curvature methods, PSD is a full field technique that does not require mechanical movement of the device or the translation of the sensor or the surface being tested; all the angular errors and positions associated with this translation are therefore avoided.
Maps Orange peel (effect)
References
External links
- Dupont Performance Coatings - including orange peel paint
- [1]
Source of the article : Wikipedia
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