Is discoloration, rainbow marks, water spots or rust on stainless steel cookware a quality defect?
No – these are normal physical reactions of stainless steel, not quality defects.
– Discoloration (yellow/brown) and rainbow marks come from overheating, dry burning and high-temperature surface oxidation; rainbow marks are safe and non-toxic.
– Water spots are mineral deposits (calcium / magnesium) left by tap water.
– Corrosion or rust spots come from leaving salty or acidic food in the pan too long, or using harsh / chlorine-containing cleaners.
Daily care: do not dry-burn the pan for a long time, use medium/low heat, avoid steel wool and abrasive tools, and dry thoroughly after each use.