The core process is identical. The difference lies in the dyeing step before sealing.
- Clear Anodizing: After anodizing, the profile is simply sealed. It retains the natural metallic silver appearance of aluminum, slightly darkened and more uniform. It highlights the metal’s luster and is very common for architectural and industrial applications.
- Black Anodizing: After anodizing, the porous oxide layer is immersed in a bath containing black dye. The dye is absorbed into the pores. The part is then sealed, trapping the dye. This provides a deep, durable black finish.
- Performance Note: Black anodizing has a higher emissivity (typically ~0.8-0.9) than clear or bare aluminum (~0.1), meaning it radiates heat more effectively, which is beneficial for heat sinks in natural convection or low-airflow scenarios.