The month of bath and vanity flooring: Part 6, more about grout

Joan Fieldstone

March 8, 2016

By: Joan Fieldstone, Home Improv Advocate

In: FlooringBathroom Remodeling

I was excited to see how the grout dried but was surprised that the color throughout the space was not uniform. Some of it was dark and some sections appeared very light. We decided to give it two full weeks to dry. I determined that regardless of what it ended up looking like, we weren't going to remove it and do it again.

Tile with lighter grout

Tile with darker grout
Some of the grout appears light and some appears darker

With the color and pattern of the tiles, the variation in shading actually looks very organic, or, ironically, as if it was done on purpose to look more "natural." In some places depending on the time of day, the grout appears to blend seamlessly with the tiles. Maybe we stumbled on a new artistic way of doing grout. Too bad we're not at all certain how it happened.

Part of this "phenomenon" may be due to the light sources in the room, both the incandescent bulbs and the natural light coming from both a western exposure on the bedroom vanity side and a northern exposure from the hall vanity side.

Grousing about grout

I looked at some forums that discuss similar problems with grout appearing to dry different colors. In these cases, professional tile contractors did the work, so this wasn't at all just a DIY blunder. BFF, if you're reading this, it happens to the pros, too.

Reading about the factors that affect final cement grout color helped me eliminate various possible causes that simply did not apply to our project such as bits of mortar left between the tiles. BFF meticulously cleaned all the mortar out before grouting. Stone tiles sometimes leach minerals that affect the curing process of the grout, but my tiles are porcelain.

Other reasons for odd drying patterns could have been responsible but we wouldn't have any way of knowing about them, such as the porosity of the tiles or how they were glazed.

Lighting, as I suspected, does affect the appearance of the grout color, and now that it's had a few weeks to cure, it doesn't look jarringly irregular as it did at first. In natural light, it's hard to notice anything unusual about it at all.

Of all the other possibilities, water seems to be mentioned the most:

  • Lack of moisture in the substrate. Moistening the tiles with a damp cloth before grouting keeps the substrate from drawing too much water from the grout as it cures.
  • Too much water in the grout mixture. It can cause the grout to dry lighter or cause efflorescence -- the salt present in the Portland cement of the grout dissolves and rises to the top where it leaves white blotches or makes the grout appear lighter when it dries.
  • Too much water in the cleanup process. Excessive amounts of water can also cause efflorescence or wash out some of the grout's pigment.

If you're taking on a grouting project, be aware of these potential issues and read up on the specific products you use. The internet is a great resource for learning tips from other DIYers and contractors.

As far as I'm concerned, the tiles look beyond beautiful. We still have to put the moldings back up and seal the grout. Penetrating sealer, which is recommended, can actually darken the grout a bit, so the appearance may change yet again. I know BFF will be happy to put this behind her, but we both love the results.

Toilet, porcelain tile, and a tub
Tiny toilet and tile, together at last


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