The short version
Against normal grey haze, a baking-soda paste or oxygen bleach with a grout brush helps. If the grout is black and spotty, it is mould, which must be treated specifically and at the cause.
Light grout greys through soap residue, limescale and dirt. That can usually be brought back mechanically with a paste and some patience. Black, spotty deposit, on the other hand, is mould, where cleaning alone does not help, but dryness and a mould remover do.
How grout gets bright again
Apply baking-soda paste
Mix baking soda with a little water into a paste and apply it to the grout.
Oxygen bleach for grey
For stronger grey haze, mix oxygen bleach in warm water and put it on the grout.
Let it act & scrub
Let it act briefly, then scrub with a grout brush, that lifts the dirt from the grooves.
Rinse off
Rinse with clear water and dry. Repeat if needed, old grout sometimes takes two rounds.
Mould? Treat differently
Black spots are mould: treat with a mould remover, wipe off damp and above all reduce the moisture in the room.
When a grout pen helps
If grout is permanently discoloured or damaged, a grout pen or grout white refreshes the look quickly. With crumbling grout, rather re-grout, that also protects against moisture damage.
What helps
What to look for:
- A grout brush and baking soda or oxygen bleach
- A mould remover for mould
- A grout pen for permanently discoloured spots
Frequently asked
How do I get grey grout white again?
What is the difference between grey and black grout?
Does a grout pen last?
When home remedies reach their limit
From the grout to the drain: the right fix for every annoyance.
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