Standard cement-based grout is porous. It absorbs everything that lands on it. In a kitchen — oil mist from cooking, splatter from the sink, occasional sauce explosions — grout goes from clean white to grimy yellow-brown within a year. Most homeowners assume this means the grout has to be regrouted. Sometimes yes, often no — depends on whether the discolouration is on the surface or absorbed into the grout itself.
Here is what actually works for restoring grout, and when you have crossed the line into needing it redone properly.
First — figure out if the grout is dirty or stained
Two different problems with two different solutions.
Surface dirt — cooking residue, dust, soap scum sitting on the grout. Cleans up with the right method and a bit of effort. Will keep coming back unless you seal afterwards.
Absorbed staining — oils and pigments that have soaked into the porous structure of cement grout. No amount of scrubbing reaches them. The grout is permanently the colour of whatever stained it.
Quick test: scrub a small section hard with bicarb paste. If it brightens noticeably, you have surface dirt and cleaning will work. If it looks the same after the scrub, you have absorbed staining and only regrouting will fix it.
If it is surface dirt — the cleaning method that works
Skip the commercial bathroom-grout sprays for kitchen grout. The stains are different (oil-based, not soap-scum-based) so the bathroom products do not work as well, and they can damage some splashback materials.
Step 1. Mix bicarb of soda with hydrogen peroxide (3% from the chemist) into a thick paste. About 3:1 bicarb to peroxide.
Step 2. Apply the paste along the grout lines with an old toothbrush. Leave for 15 minutes. The peroxide bleaches organic staining and the bicarb is a mild abrasive.
Step 3. Scrub firmly along the grout line, not across it. Across-direction scrubbing wears down the grout faster than necessary.
Step 4. Rinse with hot water and dry with a microfibre cloth.
This brings most kitchen grout back to clean if the staining is on the surface. Test on a small area first to make sure your tile finish is not affected.
After cleaning — seal it so it stays clean
Cleaned grout will start absorbing kitchen grime again immediately unless it is sealed. Penetrating grout sealer (water-based or solvent-based) goes on with a small applicator, soaks into the grout, and creates a barrier that repels water and oil.
Apply two coats. Let dry for 24 hours between coats. Re-apply every 12-18 months in a busy kitchen, less often elsewhere.
This is the step most people skip and then wonder why the grout is dirty again three months after they cleaned it.
If the grout is permanently stained — regrout, ideally with epoxy
If the bicarb test did not improve the grout, you have crossed into regrout territory. Regrouting means raking out the old grout and putting in new. Done DIY it is messy, slow, and easy to do badly. Done by a specialist it is fast, clean, and you can choose a much better grout than the standard cement that was probably used originally.
Why epoxy grout is worth the upgrade. Standard cement grout is porous and absorbs stains — that is why your existing grout went bad. Epoxy grout is a two-part system that cures into a non-porous material. It does not absorb oil, water, or pigment. It does not need sealing. It looks exactly the same once installed but lasts decades without staining.
The catch — epoxy grout is harder to install. The mix has a working time of about 30 minutes before it sets up, the cleanup is more demanding, and a poorly installed epoxy grout job is a much bigger problem than a poorly installed cement grout job. It needs someone who has actually installed epoxy before.
For Australian homeowners wanting kitchen grout properly redone, Leaking Showers Sealed handles regrouting with epoxy in kitchens as well as bathrooms — they have a specific process for kitchen splashbacks and are experienced with the messier oil-stained grout situations rather than just bathroom soap-scum.
The maintenance routine that keeps grout looking new
Whether you have cement grout or epoxy, three habits keep it looking new:
- Wipe oil and grease off the splashback while still warm — it comes off easily before it cools and bonds
- Run hot water down the splashback weekly during a kitchen wipe-down — flushes any residue out of the grout texture before it settles
- Re-seal cement grout every 12-18 months (skip this if you went with epoxy)
Five minutes a week of attention saves you a four-hour scrub session every six months — and a regrout every five years.