Glass

How do I get limescale off a shower screen without damaging the glass?

The glass association's cleaning paper excludes acids from glass cleaning solutions as a class, naming hydrochloric and hydrofluoric as its examples, and warns that glass can be permanently damaged if it is infrequently or improperly cleaned. It also rules out the two things people escalate to when the acid does not work: abrasive cleaning materials, and razor blades or metal scrapers, which are excluded from routine cleaning altogether. The mechanism it gives for scratching is not the cleaner but trapped grit, so scrubbing a gritty screen is worse than leaving it.

It cannot be removed safely — prevent it instead: Treat this as a drying problem rather than a cleaning one, because that is where the deposit is actually created. The glass paper is precise about the mechanism from the other direction: its pure-water method requires water below 20 ppm total dissolved solids and states that tap water is not acceptable, because the rinse water is allowed to evaporate in place. Ordinary tap water left to evaporate on a screen deposits exactly what it was carrying. So the intervention with evidence behind it is removing the water before it dries — squeegee or blot the screen after each use, which is the same instruction the sanitaryware manufacturer gives for metal, where allowing water to evaporate forms deposits and the technique is to blot with a dabbing action rather than rub. For scale already established, CleaningHQ has no method it can support on this substrate: the acid that would dissolve it is excluded by the glass authority, and abrasives and blades are excluded too.