Which Surface Treatment is more Suitable for Hardware: Phosphate Conversion or Black Oxide Coating?

Hardware manufacturers are good at oxidation and coloring of aluminum alloy, as well as blackening and phosphating steel. Parts that have undergone these surface treatments will have better wear and corrosion resistance. We will discuss briefly below on the characteristic of phosphating and blackening treatment:

1. Phosphating and Blackening are Chemical Conversion Coating Treatment

Both surface treatments are chemical conversion coating treatment that could protect metal surface against corrosion and wear. They are immersed in a bath solution to achieve surface finish.

2. Blackening has a Smoother and Shinier Finish

According to various feedback from our clients, blackening treatment has a smoother and shinier finish compared to phosphating. This is because phosphate conversion coating having a thicker film, causing it to be darker and somewhat porous compared to blackening, which has a thinner film.

3. Forming Principle of Phosphating and Blackening is Slightly Different

Many hardware manufacturers believe that parts can achieve the same level of corrosion and wear resistance regardless of phosphating or blackening film. This is however false, as phosphating mainly refers to formation of insoluble phosphate film on the surface of base metal in a phosphoric acid solution, while blackening mainly forms a protective film through immersion of a high temperature alkaline cleaner and blackening compound.

In conclusion, both methods can achieve high level grade protection to the parts finish. However, depending on the protection and finish requirement, one will have an advantage to the other, and vice versa. The other key deciding factor is choosing a reputable manufacturer in creating the product as they are equipped with high level surface treatment technology, good quality control and knowledge to choosing the best method to accommodate the requirement needed.