Chloride attack
The specific reason stainless steel does rust. Chloride ions break the passive film locally, and the damage concentrates in a pinpoint.
In detail
Stainless steel resists corrosion because chromium in the alloy forms a very thin oxide film that repairs itself in the presence of oxygen. Chloride ions are the household chemistry that defeats it. They penetrate the film at weak points, and because the attack is local rather than general, the corrosion concentrates into deep pits rather than spreading as a even rust layer — which is why a stainless sink can look perfect apart from a few dark pinpoints. The sources of chloride in a house are ordinary: table salt, food residues, bleach and chloride-containing cleaners, and de-icing salt carried in on shoes and vehicles. The practical rules follow directly. Do not leave salted water standing in a stainless pan, do not add salt to water before it boils, do not leave bleach in contact with a stainless surface, and rinse and dry after cleaning rather than leaving a film to concentrate as it evaporates. The same mechanism explains why winter is hard on vehicle sills, garden tools and outdoor metalwork, and why rinsing them matters more than their appearance suggests.
Why
- Road salt is explained by Chloride attack
- Stainless steel is explained by Chloride attack
- Stainless steel cleaner is explained by Chloride attack
Sources for this page
Sources
Care and Maintenance of Stainless Steel
British Stainless Steel Association, Stainless Steel Advisory Service, 2001 · Trade or professional body
Relied on for: That chromium forms a self-repairing passive layer on stainless steel, that chlorides attack that layer, and that the result is pitting corrosion. (states this directly)
Verification: a person has read the passage relied on.
Read on — Sprint 29 re-read all four pages: Factors Affecting Maintenance, Maintenance Programme, Cleaning Methods with the whole of Table 1, Table 2, and Notes 1-10. Earlier sprints named both tables but carried only part of one and none of the notes. Supports a wider statement — our claim was widened. SPRINT 29 FOUND THIS UNDER-EXTRACTED WHILE ALL THREE SIGNALS CALLED IT DONE: zero representation debt, in the fully-harvested list, and honestly noted as 'read in full'. Five of Table 1's eleven rows, all of Table 2 and eight of ten notes had never reached the graph. Newly built: tannin and coffee deposits, heat discolouration, the 1% ammonia routine clearance, oxalic acid for embedded iron, and the condition-triggered domestic frequency rule. The paraphrase cap is part of the cause, and the fix is not a longer paraphrase — the facts belong in the citing records.
Right to Know Hazardous Substance Fact Sheet: Sodium Hypochlorite
New Jersey Department of Health · Government or regulator
Relied on for: That sodium hypochlorite is a corrosive chloride-bearing oxidising agent. (cleaninghq's interpretation of what it says)
Verification: a person has read the passage relied on.
Read on — Description and Use, Hazard Summary, Health Hazard Information, Handling and Storage, and the Emergency Responders reactivity panel on the back page. Re-read in full in Sprint 27. Supports a narrower statement — our claim was reduced. This does NOT establish that bleach damages a stainless steel sink or an aluminium pan in ordinary surface cleaning, and CleaningHQ does not model it as though it did. What it establishes is a CONTAINMENT AND STORAGE constraint — bleach should not be held in metal equipment or piping, because oxygen release can rupture the container. The domestic pitting claim for stainless steel rests instead on the stainless trade association's guidance about prolonged soaking, a separate fact from a separate source, and the two are deliberately not merged.
Last reviewed by a person on .