13 April 2009

How to clean a grout joint

I get asked how to clean white grout all the time and my answer is usually, "Don't have white grout." Seriously, short of regrouting your tile every six months, white grout joints are nearly impossible to clean and keep that way.

However last weekend, I came across this article in the St. Pete Times. It's written by Tim Carter, a general contractor and syndicated columnist. Carter runs a website called AskTheBuilder.com and it's chock full of advice and how-to videos. He tackled the problem of white grout joints in a way I'd never considered.

His method involves the so-called oxygen bleaches that seem to be all the rage. Oxygen bleaches do use oxygen to power away organic and some inorganic matter, so I suppose I shouldn't use the expression so-called. However, how they're pitched is so laden with inaccurate descriptions of how they work I feel compelled to continue to use the so-called moniker for them.

So-called oxygen bleaches are made with sodium percarbonate. When sodium percarbonate is dissolved in water It breaks down and releases elemental oxygen that then bonds to whatever it can grab. Sodium percarbonate is hardly a benign substance. If it were benign it wouldn't work. As it breaks down, it leaves behind oxygen and carbon it's made from. These elements are less harmful than the leftovers from other cleaning compounds, but still, none of this stuff is non-toxic. While it's true that you need oxygen to live, pure oxygen will kill you believe it or not.

File this under the for what it's worth column, but chlorine bleaches also use elemental oxygen to do their thing. Household bleach is a solution of sodium hypochlorite and water. Sodium hypochlorite is made from table salt. Dissolved in water, sodium hypochlorite breaks down into elemental oxygen and hydrochloric acid. The atomic oxygen is what does the bleaching, but the hydrochloric acid goes looking for carbon bonds to break. This is not always a bad thing, hydrochloric acid is also the active ingredient in your stomach acid. The hydrochloric acid left behind by chlorine bleach may help you digest your dinner, but it does the same thing to the grout joints on your floor. That's why using chlorine bleach on masonry, concrete or grout is a bad idea.

Anyhow, here's what Tim Carter recommends to clean grout joints.
To clean floor tiles, all you need to do is mix any high-quality oxygen bleach with warm water and stir it until it dissolves. The next step is to pour the solution onto the floor tile so the grout lines are flooded, as if you had spilled a glass of water. It's best to apply the oxygen-bleach solution to dry grout so the solution soaks deeply. Let it sit for at least 15 minutes to allow the oxygen bleach to work. If it completely soaks in, add more solution, making sure there is always plenty on the grout.

The longer you let the solution sit, the less work you have to do. The oxygen ions work for up to six hours. To get maximum cleaning results, scrub the grout lightly after 30 minutes. Always pour new solution onto the grout as you scrub. You have to always scrub a little, but that's how anything gets clean.

Once you have clean floor tiles, keep the grout looking good by adding oxygen bleach powder to your mop water. Apply a liberal amount of mop water to the floor, scrubbing the tile surface with the mop. Leave the mop water in the grout joints without rinsing the floor; the oxygen ions will clean the light dirt in the grout without scrubbing. Come back 30 minutes later and rinse the floor with clean water. Do this each time, and you can avoid scrubbing the floor altogether.

Don't worry if your tile floor is installed next to carpeting. The oxygen-bleach solution will not hurt the carpet and can clean it. In fact, to clean carpeting with oxygen bleach, simply mix up the solution and use a sprayer to saturate the carpet fibers. Let the solution soak for 30 minutes, and then use a regular carpet shampoo machine to finish the job.

You also can mix up small amounts of the solution to handle small spills, such as wine or cranberry juice. It's always best to work on stains while they're fresh, but tile floors that have been dirty for years will come clean in no time with oxygen bleach.
I was over at a previous client's yesterday and he'd read the same article. In a miracle of timing, he was in the middle of cleaning his floors with Oxy Clean so I had the chance to see this at work. And it did work. If you have a dirty grout joint problem, give this a try. Sodium percarbonate doesn't work as quickly as sodium hypochlorite, but it does work.


  1. Can I assume I'd have the same positive results on wall tiles & grout? And what about a non-sanded white grout... still problematic? And can it benefit from this process?

    Thank you so much, Paul, for dropping by DesignTies and sharing your definition of interior design!!


  2. Based on what little chemistry I know, I'd do a test patch first and see what it does. Bleaching, regardless of the process, is the action of oxygen on color molecules. Some are better able to resist bleaching and some aren't. So do a test patch in a less-noticeable area and see how it goes.

  3. Paul, I love learning new things such as how to clean white grout. You mentioned Oxy Clean... is this the same stuff used in the washing machine to get stains out?

    Not knowing anything about oxygen bleach, where would I purchase it? Is it a liquid or a powder?

  4. Yes, it is the exact same thing Susan. Sodium percarbonate is the active ingredient in Oxy Clean and a host of other powdered, non-chlorine bleaches. I'm sorry if I was vague about that.

    These powdered, percarbonate bleaches are readily available and have gone pretty mainstream. Even Oxy Clean (if the informercial fame) is a brand owned by Arm and Hammer. Just check the laundry aisle at any grocery store.

  5. thanks for the useful tip. I'm going to have to clean that blasted grout in our kitchen before we move. What a hateful chore.

  6. Ahhh yes, you have a tile counter in your hateful kitchen. Why not make a test case out of yourself and try this method and report back? I'd be curious to hear how it works on a counter.

  7. I sure will! I'll even do before and after photos.

  8. Solid! That would be great Melody. Let's make a whole guest post out of it. Take lots of photos! This'll be great, a real live test case.

  9. Yeah archives! Question: Can nicotine stain grout? B/c no amount of bleach, scrubbing or magic has been able to get rid of the yellow color in my bathroom tile...?? I think I'm screwed. sad face.

  10. As a point of order, it's the tar that leaves a satin, not the nicotine. OK, now that that's out of the way.

    If your grout is old it may be that the pigments or binders have aged and can't go back to white. If that's true then it's time to break out the Dremel and get rid of the old grout.

    Try the OxyClean method first. Tri Sodium Phosphate might work too.

  11. thanks for clarifying! Might be time for sledgehammer over Dremel... ; )


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