Sandblasting is a widely used surface treatment process in the machining industry. However, many professionals notice color variations on the blasted workpieces, affecting both aesthetics and subsequent processes such as painting, oxidation, or coating. What causes these inconsistencies, and how can they be effectively prevented?
Main Causes of Color Variation in Sandblasting
1. Type and Condition of Abrasive Media
Different abrasives (e.g., brown corundum, glass beads, steel shot) produce different surface finishes and colors.
Worn-out or broken abrasive particles reduce blasting efficiency, leading to uneven coloration.
2. Blasting Pressure and Nozzle Angle
- Excessive or insufficient pressure alters surface roughness, causing color differences.
- Inconsistent nozzle angles create varying impact intensities, leading to uneven blasting effects.
3. Base Material and Oxidation State
- Different metals (e.g., aluminum alloys, stainless steel, carbon steel) exhibit different colors after blasting.
- Varying oxidation layer thicknesses on the workpiece surface may result in different base material colors once removed.
4. Environmental Factors and Humidity
- High humidity can cause abrasive media to clump together, leading to uneven blasting.
- Moisture on the workpiece surface may cause slight oxidation after blasting, affecting color consistency.
How to Prevent Color Variation in Sandblasting?
1. Select the Right Abrasive and Replace It Regularly
- Choose abrasive media based on the workpiece material and ensure uniform particle size.
- Regularly replace or filter abrasives to prevent using excessively worn-out media.
2. Control Blasting Parameters
- Maintain consistent blasting pressure, ideally between 0.4–0.6 MPa (depending on the material).
- Keep a uniform nozzle angle and distance to avoid localized color differences.
3. Standardize Workpiece Preparation
- Remove oil stains and oxidation layers before blasting to ensure uniform material exposure.
- Use materials from the same batch to minimize differences in base material composition.
4. Optimize Blasting Environment
- Maintain workshop humidity between 40%–60% to prevent moisture-related issues.
- Use dry compressed air to eliminate the risk of water vapor affecting the blasting process.
Conclusion
Color variation in sandblasting mainly results from abrasive selection, pressure control, base material differences, and environmental factors. By choosing the right abrasives, optimizing blasting parameters, ensuring proper workpiece preparation, and controlling environmental conditions, manufacturers can significantly reduce inconsistencies and achieve a uniform surface finish.
If you're experiencing sandblasting color variation or need expert guidance on surface treatment solutions, feel free to contact Jiangsu Henglihong Technology Co., Ltd. (www.hlh-js.com). We specialize in professional surface finishing technologies and customized solutions!
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