Mirror scale is dried-on tap-water minerals
#0030 Home & daily life
Fact rank
A
Confirmed by an industry body, a housing-fixtures maker and a cleaner manufacturer; the claim that silica does not dissolve in acid could not be confirmed in primary or secondary sources and is left to the notes
Wow rank
S
The surprise that the scale is just tap water
Usefulness
A
A clear use when choosing a bathroom cleaner
Verification: Supported by evidence
AI verification reports the evidence it found; it does not guarantee that a claim is true.
The white scale on a bathroom mirror is minerals in tap water, such as silicon and calcium, left behind when it dries. The calcium part can be removed with an acidic cleaner such as citric acid.
Why
When the water evaporates the minerals stay behind and build up. The calcium in limescale dissolves in acid.Evidence
Secondary Japan Soap and Detergent Association: limescale is minerals in the water (silicon, calcium and so on) link
Primary LIXIL: limescale is caused especially by calcium; the calcium in limescale is weakly alkaline link
Primary Cleaner manufacturer (Seikatsu to Kagaku Sha): so-called limescale is the grime that acid removes link
Notes and limits
Scale high in silicon (silica) is said to resist acid and to need scraping off with an abrasive, but this could not be confirmed in manufacturer or research material. On mirrors with an anti-fouling coating an abrasive may remove the coating too, so check the mirror's care instructions. Never mix acidic cleaners with chlorine-based ones.
Derivations
Derived from: 汚れと洗剤は相性で選ぶ
Derived facts: —