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The Spokesman-Review Newspaper
Spokane, Washington  Est. May 19, 1883

Ask the Builder: Tile grout color can deceive before fully dry

This bathroom floor was installed by a DIYer. He can’t understand why the grout is not the color he wanted.  (Tim Carter)
By Tim Carter Tribune Content Agency

Q. I made a mistake and discovered your detailed floor grouting video series a bit too late. I should have watched them before I started my job, but what’s done is done. Five hours ago, I grouted my bathroom, and the color of the grout is not what I want it to be. It doesn’t match the color stripe on the bag. I think I see efflorescence on the edges of the grout where the color of the grout is whitish. What did I do wrong? What can I do to get the grout to the color I want? How can you get a perfect color match when doing tile grout? – Michael B., Quebec, Canada

A. This is a common enough problem. When my son-in-law was dating my daughter in college, he was working for me part time helping me on my website. After a few days he said, “Mr. Carter, you’re in the life-preserver business. I can see from all your emails that people come to you for help because they failed to take the time to discover exactly what to do before they put a tool in their hands.”

Sadly, not much has changed in 13 years, and it’s become worse. You might think you know what you’re doing, or you might start a project after receiving some bad advice from any number of sources. Only after your DIY ship starts to sink do you then flail about in the water shouting for help. Sometimes the fix is easy. Sometimes you have to rip things out and start over.

Michael provided some interesting clues. The biggest one is he reached out to me only after five hours. You might not think that’s important, but it is. I’d venture to say his wide and deep grout lines have yet to fully dry. He points out that he sees a “whitish” color on the edges of the grout. That’s another important clue.

Grout almost always appears darker when wet than when dry. New grout can take 24 or even 48 hours before it’s completely dry. It depends on the humidity and temperature in the room where the grout is installed.

While grout manufacturers no doubt try to get the color stripe on the bags to be a true representation of the color of the dried grout, you can’t count on that. If you use pure water to mix the grout and don’t mix in any liquid additives, you can almost always count on the installed dry grout to look almost identical to the color of the grout when it comes out of the bag. Your job is to test this before you start to add grout between the tiles.

Michael should have mixed up a small amount of the grout and applied it between several small scraps of tile left over from the installation. He should have let the grout dry for three days and then compared it to the color of the grout as it comes out of the bag. You should do the same. If you have a tile contractor, ask him to do this so you know the grout color will be what you want.

The efflorescence that Michael is referring to is not efflorescence. It’s simply the colored cement paste of the grout fully dry where it’s maybe as thin as a hair on your head. You often see this same grout haze on the surface of the tile an hour or so after you’ve finished grouting. In many cases, this fine grout residue is almost a perfect match for the dry color of the grout.

Be aware that liquid grout additives can drastically alter the color of the installed grout. I found this out the hard way many years ago. I followed the instructions to the letter when using the additives, using nearly no water to strike the joints, and even still my grout dried blotchy. My wife was upset, and it took me many hours on my hands and knees using an artist’s brush and special penetrating oil-based grout stain to get the grout to look a uniform color. I have never used a grout additive since then.

If you find yourself in a mess like Michael, the first thing to do is relax. Wait a few days and see what color the grout is when fully dry. I’m thinking Michael is going to be pleasantly surprised. He needs to pour some of the unmixed grout from the bag onto the floor next to a grout line and compare the color. My guess is it’s going to be very close if not a perfect match.

If you do need to change the color of the grout, you can purchase penetrating stains that are nearly identical to wood stains. You have to slowly and carefully apply these to the grout lines and not get any on the tile. It can be a wretched process.

The problem is that it’s almost impossible to go from a dark grout to a light color with these stains. You can always go from lighter grout to darker with no effort. Beware of products that falsely claim to be grout stain when in fact they’re simply thinned paint. You don’t want a product that forms a film on top of the grout. You want a true penetrating stain that soaks into the grout matrix.

If you want to see the correct way to grout a tile floor ensuring the color turns out the way you want it, I urge you to watch the four tile-grouting videos on my website. Just go to

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