When we moved into our house, I honestly thought the grout on the bathroom floor was supposed to be grey. Then I scrubbed a test patch and saw a lighter line underneath. The dirt in grout is mostly soap residue, skin oils and dust ground into a porous surface, so it needs something that bubbles into the pores. A paste of baking soda and ordinary 3% hydrogen peroxide does exactly that, gently and without harsh fumes. It will not make old, stained grout look brand new every time, but on most floors and walls the difference is huge.
What you need
- 1/2 cup (about 110 g) baking soda (bicarbonate of soda)
- 1/4 cup (60 ml) 3% hydrogen peroxide (the standard pharmacy strength)
- 1 tsp (5 ml) dish soap
- 1 old toothbrush or narrow grout brush
- 1 small bowl
- 1 bucket of warm water and a sponge
- 1 pair rubber gloves
How to do it
- Sweep or vacuum the floor, then wash the tiles with warm water so you are working on grime, not loose dust and hair.
- Put on gloves and open a window. In the bowl, mix the baking soda, hydrogen peroxide and dish soap into a spreadable paste. Make it fresh, just before using, and do not store it in a closed container.
- Test on a small hidden area first, especially if your grout is colored, since peroxide can lighten some tinted grouts.
- Spread the paste along the grout lines with the toothbrush or a spoon, working one area of about 3 by 3 feet (1 by 1 meter) at a time.
- Leave it for 10 to 15 minutes. You will see light fizzing as it works into the pores.
- Scrub along each line with the brush, using short back-and-forth strokes. The grey residue comes up in the paste.
- Rinse well with clean warm water and the sponge, changing the water once it turns cloudy, then dry the floor with a towel and let the grout air dry completely.
Good to know
- Never mix hydrogen peroxide with vinegar in the same container, and never add bleach to this paste.
- Skip this method on natural stone such as marble or limestone; use a cleaner made for stone instead.
- Once the grout is clean and dry, a grout sealer from the hardware store helps it stay clean much longer.
- Grout that is cracked or crumbling needs regrouting, not more scrubbing.
Do one strip, step back and look at the difference. That is the moment you know the rest of the floor is worth it. Tell me how yours came out!
