Refresh dingy grout in 2 hours (no removal needed)

Try this before regrouting

If your grout is intact but discoloured, you don't need to chip it out. A deep clean and a grout pen will buy you years.

What you need

• Stiff-bristle grout brush (~$5)
• Baking soda + hydrogen peroxide
• Grout pen in white or grey (Home Hardware, $10)
• Painter's tape
• Microfibre cloth

Steps

1. Mix a paste: 2 parts baking soda + 1 part 3% hydrogen peroxide.
2. Apply to grout lines with an old toothbrush. Let it sit 10 minutes.
3. Scrub each grout line with the grout brush.
4. Rinse with clean water and a sponge. Let dry fully (2 hours).
5. Tape off tile edges if you're worried about overspray.
6. Trace each grout line with the grout pen. Cap the tip frequently to avoid drying out.
7. Let it cure 24 hours before getting it wet.

When to actually regrout

• Grout is cracked, missing, or crumbling
• Tile is loose
• Mold has gone into the grout (smell test)