Vinegar for mirrors and glass

Does it work?

Does not work

Refuted for mirrors by the trade body that speaks for them, in explicit terms naming the substance. For plain glazing the same industry's restriction names stronger acids and does not reach acetic, which is a different question with a different answer.

This is a verdict on whether the technique is effective. Whether it is safe on a particular surface is a separate question, answered below.

Where not to use it

The proposed mechanism

The explanation below is what is offered for this technique. No evidence establishes that this is what actually happens, so treat it as a plausible story rather than as a finding.

Acetic acid dissolves the mineral deposits left by hard water and cuts light greasy films, and it evaporates without residue, which is a genuine advantage over a surfactant that must be rinsed. On bare glass the reasoning holds. What it does not account for is that most domestic glass worth cleaning is not bare: a mirror has a coating and a backing reachable at every edge, and the paper's objection is to what the acid does there rather than to what it does to the glass face.

Background

This is the most confidently held belief in domestic cleaning, and the trade body responsible for mirrors contradicts it directly: do not use commercial mirror cleaners that contain ammonia or vinegar. The reason is not the glass. A mirror is glass plus a reflective coating plus a backing, with all three exposed at the edges, and the same paper states that acid or alkali cleaners can attack the front surface, the edges and the backing. Vinegar is the acid and ammonia is the alkali, so the household remedy and the supermarket bottle fail for the same structural reason at opposite ends of the pH scale. The failure has a name — black edge — and it is progressive, which is why a routine can feel successful for years. The recommended method is plain: clean warm water on a soft lint-free cloth, wrung out, dried immediately, with the cleaner applied to the cloth and never sprayed at the mirror so that nothing runs into the edges. For plain glazing rather than a mirror the constraint is looser but not absent; the glass trade's cleaning paper rules acids out of glass cleaning solutions, naming hydrochloric and hydrofluoric rather than acetic.

What it does not do

• The prohibition is stated for mirrors; the glass paper's acid restriction names hydrochloric and hydrofluoric rather than acetic
• Neither source quantifies concentration or contact time, so the point at which vinegar becomes harmful is not established
• Black edge is progressive, so an apparently successful routine is not evidence of safety

What to use instead

• Water — The solvent almost all cleaning happens in, and on its own the right answer more often than it is given credit for.
• Microfibre cloth — Split synthetic fibres with a very large surface area, which lift and trap soil mechanically — often with water alone.
• Rinsing and drying — The step people skip, and the one that decides whether cleaning protected the surface or damaged it. Residue left behind is exposure that continues after you stop.