Understanding pH, and why it decides what works
Most cleaning failures are a pH mismatch rather than a lack of effort. Here is the short version.
1 minute
Almost every cleaning problem is either acidic or alkaline, and the fix is the opposite. Limescale and soap scum are alkaline mineral deposits, so an acid removes them. Grease and burnt-on food are acidic, so an alkali breaks them down. Scrubbing an alkaline deposit with an alkaline cleaner is the most common wasted afternoon in the house.
That is why vinegar clears a kettle and does nothing for an oven, and why soda crystals cut through grease and leave limescale untouched. Neither product is better; they are aimed at different problems.
It also explains the one rule worth memorising: acids attack calcium. Marble, limestone, travertine and unglazed terracotta are calcium-based, so an acidic cleaner does not clean them, it etches them. The damage is permanent and it is not a stain — the surface itself has been dissolved.
