Possible causes: This is not a material defect. It is typically caused by corrosive gases and liquids left after renovation (such as cement and paint agents) causing oxidation, or long-term exposure to acidic or alkaline substances. Hard water (rich in iron/calcium) may also contribute.
Solutions: 1) For light rust: Use a cloth dipped in toothpaste or neutral detergent to wipe along the brushed grain. 2) For stubborn rust: Clean with a scouring pad + stainless steel cleaner/talcum powder, and avoid using steel wool. 3) Daily care: Clean the sink promptly after renovation and avoid contact with highly corrosive substances.

Possible causes: Using steel wool or hard tools during cleaning, or friction from cookware.
Solutions: 1) Repair scratches: Use a medium-soft scouring pad/brush cloth, gently rub along the grain, and then lightly wipe quickly to restore the grain. 2) Daily care: Avoid placing sharp objects directly and use a soft cloth + neutral detergent for cleaning.

Possible causes: Some sinks use 201/202 stainless steel while claiming to be 304, which compromises corrosion resistance.
How to identify: 1) Check the mark: Only “SUS304” is legitimate. Labels such as “DUS304” are counterfeit. 2) Test with reagent: Purchase stainless steel testing reagent, apply it to a small area on the back (after lightly sanding it), and observe the color change. 3) Weighing: 304 stainless steel has a higher density and will feel noticeably heavier than inferior materials.

Possible causes: The drainpipe is bent or clogged, or the drainage outlet is higher than the trap in the drainpipe.
Solutions: 1) Shorten the drainage hose to ensure a natural and smooth insertion into the drainage outlet. 2) Check and clear the pipes and adjust the drainage outlet's height to be lower than the trap. 3) Regularly clean the filter residue to prevent oil accumulation.