Material compatibility
The reason a useful answer is about the surface rather than about the product. The same agent is the right answer and the wrong answer depending on what it lands on.
In detail
Compatibility is not a property of a cleaning product. It is a relationship between the product and the surface, and it exists because the mechanisms that remove soil are chemical reactions that do not distinguish targets. An acid dissolves calcium carbonate: that is what descales a kettle and what etches a marble worktop, and it is the same reaction in both cases. An alkali hydrolyses proteins: that is what lifts a food stain and what degrades a wool fibre. An oxidiser breaks the chromophores that carry colour: that is what removes a wine mark and what strips a garment's dye. In each pair the agent is not behaving differently — the surface is simply made of the same class of material as the soil. This is the single most useful generalisation in the subject, and it produces a working rule: before asking whether a cleaner is good, ask what it is chemically, and then ask whether the surface is made of anything in the same family. Where the answer is unknown, it stays unknown. Nothing licenses an inference that an untested combination is fine, because there is no chemistry that would justify one.
Why
- Acetic acid (vinegar) is explained by Material compatibility
One agent, one mechanism, opposite answers on a kettle and a worktop.
- Finished wood flooring is explained by Material compatibility
The clearest case after painted steel: the cleaner is chosen for the FINISH, and what the timber tolerates is irrelevant while the film is intact.
- Solution-dyed acrylic is explained by Material compatibility
- Spot testing is explained by Material compatibility
- Neutral cleaning is explained by Material compatibility
Sources for this page
Sources
Care & Cleaning of Natural Stone
Natural Stone Institute · Trade or professional body
Relied on for: That the same acidic substances which are effective cleaners elsewhere dull or etch calcareous stone, and that the recommended cleaner is chosen by stone class. (applied to this case rather than stated directly)
Best detergent to use when washing wool
The Woolmark Company · Trade or professional body
Relied on for: That enzyme-containing detergents effective on protein stains are advised against for wool, a protein fibre. (applied to this case rather than stated directly)