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Relative hardness

Whether an abrasive scratches a surface depends on which is harder. That is the entire question, and it is knowable in advance.

In detail

Scratching is not a property of a cleaning tool; it is a relationship between two materials. A harder material marks a softer one and never the reverse, which is why the same scouring pad leaves one surface unmarked and ruins the next. Ranking the household materials makes most compatibility questions answerable without testing. Diamond, silicon carbide and quartz sand sit at the top; hardened steel and steel wool are next; glass, glazed porcelain and vitreous china are close behind; then softer metals such as chrome plate, aluminium and brass; then acrylic, most plastics, painted finishes, lacquers and coatings near the bottom. Calcite — the mineral in the mildest cream cleansers — is soft enough to clean glazed ceramic without marking it, which is precisely why it is chosen. Two consequences follow. Steel wool marks stainless steel, glass-ceramic and chrome, because steel is harder than all of them. And melamine foam works as a very fine abrasive, so it burnishes matt paint and hazes clear coats. The rule to carry is that the abrasive must be softer than the surface, not merely 'gentle'.

An ordered vertical scale from hardest to softest, with household abrasives and household surfaces marked distinctly on the same axis so that any pair can be read against each other.
An ordered vertical scale from hardest to softest, with household abrasives and household surfaces marked distinctly on the same axis so that any pair can be read against each other.

Why

Sources for this page

Sources

  1. Right to Know Hazardous Substance Fact Sheet: Silica, Quartz (RTK 1660)

    New Jersey Department of Health, 2016 · Government or regulator

    Relied on for: That crystalline silica is used as an abrasive and is a hard mineral solid. (states this directly)

    Verification: a person has read the passage relied on.

    Read on — The 'Description and Use' paragraph and the hazard summary banner. Supports the claim as stated. Gives the abrasion records a sourced statement about what an abrasive particle IS and why a dry mineral powder is handled differently from a cream. It does not support any statement about scratching, which is a mechanical question this sheet does not address.

  2. Care and Maintenance of Stainless Steel

    British Stainless Steel Association, Stainless Steel Advisory Service, 2001 · Trade or professional body

    Relied on for: That steel wool and carbon-steel implements damage stainless steel and leave iron particles which corrode. (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.

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