Why does color difference occur after sandblasting and welding of stainless steel wire mesh?

Stainless steel wire mesh is used for screening and filtration in acidic and alkaline environments. In the petroleum industry, it's used as mud screens; in the chemical and fiber industries, as filter screens; and in electroplating. Local melting or melting of another part of the stainless steel wire mesh can cause two or more unrelated components to bond together. This can lead to discoloration due to high temperatures. For aesthetic reasons, it's recommended to perform a complete acid pickling and polishing after finishing. Why does color difference occur after sandblasting or welding of stainless steel wire mesh?
A passivation film forms on the surface of the stainless steel wire mesh, existing in nature as a more stable oxide. While the degree of oxidation varies depending on the usage conditions, all stainless steel wire mesh will eventually be oxidized; this phenomenon is called corrosion. Dust and easily removable dirt on the surface of stainless steel wire mesh can be washed with soap, mild detergent, or warm water.
If bleach or various acids adhere to the surface of the stainless steel wire mesh, rinse immediately with clean water, then soak in a neutral sodium bicarbonate solution or ammonia solution, and finally wash with warm water or a neutral detergent. During the weaving process of stainless steel wire mesh, multiple steps are involved, including wire drawing, diameter adjustment, weaving, and flattening. Therefore, some oil or dirt inevitably accumulates on the surface of the wire mesh during this process.
This necessitates surface cleaning and descaling of the wire mesh to ensure its appearance and quality. Grease, oil, and lubricating oil contaminants on the surface of the stainless steel wire mesh should be wiped clean with a soft cloth, followed by cleaning with ammonia solution, a specialized detergent, or a neutral detergent.