Causes of different types of towel racks rusting

Copper chrome towel rack
The raw material is brass, the "rust" of copper is different from that of iron, so why do customers sometimes report rust at home? There are the following situations:
1. The coating of the towel rack is not well protected, which leads to the destruction of the coating. When the brass is in contact with the air, it may grow "patina" in a humid environment.
2. It is not wiped often. Over time, some water scums form dirt on the surface and eventually show spot-like black spots.
3. Poor water quality, containing metal ions, coupled with no regular wiping, or some hygienic dead areas, these metal ion-rich water droplets and air act, and rust may occur over time.
Alumina towel rack
Pure aluminum products have poor hardness and will blacken, but the oxidized aluminum oxide products have greatly improved hardness, will not blacken, have good wear resistance, and aluminum oxide products will not rust.
Stainless steel towel rack
Low-grade stainless steel will rust. The higher the chromium content of stainless steel, the less likely to rust. The chromium content of 304 stainless steel is 18%. It has good stability and strong corrosion resistance, even if it is placed in a humid environment for a long time. Will rust.
Zinc alloy towel rack
Zinc alloy towels will not rust. But the quality is not as good as other materials, and it is easy to break.