How to Clean Tile Grout and Bring the Colour Back

Grout darkens for two reasons, and which one you have decides everything else. Surface dirt and soap film wash off. Mould that has grown into the cement joint does not: you can bleach it, but it will show through again within months. The first thing to do is tell them apart.

What you need

• Baking soda — 3 tablespoons
• Hydrogen peroxide 3 % — 100 ml
• Washing-up liquid — 1 teaspoon
• A grout pen — for restoring colour

• An old toothbrush or a dedicated grout brush
• Microfibre cloth
• A steam cleaner, if you have one
• Gloves

Time: 90 minutes for a standard bathroom.

Step by step

1. Identify the soiling. Rub the joint with a damp cloth: if it lightens, it is deposit; if the colour holds and you can see black specks in the depth, it is mould.
2. Mix the paste. Three tablespoons of soda, 100 ml of peroxide, a teaspoon of washing-up liquid, to the consistency of thick cream.
3. Apply to the joints. With the brush, into the joint only, not smeared across the tile: soda leaves matt marks on gloss.
4. Leave twenty minutes. The peroxide lightens while the soda softens the deposit.
5. Work the brush. Along the joint, in short strokes, without heavy pressure — cement is softer than tile.
6. Rinse and dry. Warm water, then wipe dry and ventilate the room for twenty minutes.

Method 2 — steam

A steam cleaner lifts deposit and surface mould out of the joint with no chemicals at all: pressurised hot steam drives the dirt out of the pores. It is the safest method for grout because it does not attack the binder. The one limitation is epoxy grout, where steam achieves little and only mechanical work and specialist products help.

Method 3 — restoring colour

If the joint is clean after washing but grey, that is not dirt but washed-out pigment. A grout pen is effectively paint in a convenient form: applied to a dry joint, the excess wiped off the tile with a damp cloth. It lasts a year or so in a dry area and less in a shower. It is cosmetic, and worth treating as such.

What to avoid

• Acidic products on cement grout. Acid washes out the binder: the joint lightens but starts to crumble and absorb water.
• Wire brushes. They take the top layer of grout off with the dirt, and it soils twice as fast next time.
• Bleach on coloured grout. It lightens unevenly, and the patches look worse than the original darkening.
• Painting over mould. It keeps growing under the pen and shows through within a month.

When grout needs replacing, not washing

Three signs make washing pointless. The joint crumbles under the brush — the binder has failed and nothing restores it. There is a visible gap between tile and grout — water is already getting behind the tile. The black returns within two or three weeks of a proper bleaching — the mould is growing from the damp layer underneath.

In those cases the grout is raked out and replaced, which is a few hours of work and no longer cleaning. We do not do it and say so plainly rather than washing something that needs repairing.

When to call a cleaner

Grout is the slowest part of a bathroom: the brush moves slowly, and a standard bathroom takes an hour and a half of joints alone. It makes sense to hand it over with the whole room: bathroom cleaning costs from UAH 450 and comes as part of a flat clean from UAH 1,550. The cleaner brings products matched to the surface and a steam cleaner — precisely the tool most homes do not have, and it does most of the job without harsh chemicals.

Frequently asked questions

What whitens tile grout?

Soda with hydrogen peroxide, twenty minutes of dwell time. Bleach is not used on coloured grout.

Can grout be steam cleaned?

Yes, it is the safest method for cement grout. On epoxy grout steam does almost nothing.

Why does the black keep coming back?

It is mould growing inside the joint. Surface bleaching does not kill it — the grout has to be replaced and the damp dealt with.