Limescale is dissolved calcium and magnesium left behind when hard water evaporates. Every drop that dries on a shower screen leaves a little more of it, and each layer is harder to remove than the last.

Left for long enough it stops being a deposit on the glass and becomes damage to the glass itself, at which point no product will restore the clarity.

Removing what is there

An acidic descaler dissolves the deposit — but acid and natural stone do not mix, and neither do acid and coated glass. Identify the surface before choosing the product, not after.

Stopping it returning

A squeegee after every shower removes the water before it can evaporate, which is the whole mechanism. It takes fifteen seconds and does more than any product sold for the purpose.