Mosaic Grout Rules

Artist Caroline Bommer’s recent Sunset Mosaic is a great example of an exception to the rules of mosaic art that I harp on in all my online content. After seeing the finished mosaic, I actually wanted to title this article, “Don’t Listen to Me. I Don’t Know Anything about Mosaic.”

Exceptions to Rules of Art

I have often written about how much I like exceptions to general rules and how problematic artistic advice can be, especially when dispensed and consumed as a one-size-fits-all way.

First, there are many different styles of art. If you are trying to paint in a loose Impressionistic style, then following advice about how to paint in the French Academic style with all its crisp rendering will leave you farther from your goal.

I would caution anyone reading different art instruction books to keep that in mind.

I even recommend that you avoid reading some content out of idle curiosity when you know the style being discussed is different from what you are trying to do.

The reason I say that is in creating art, there are many decisions that are made in a less-than-fully-conscious way.

When learning something new and complex, the last thing you need is to cloud your judgment with too many conflicting ideas in the back of your mind. At least that has been my experience.

Sunset Mosaic Backsplash, pre-grout. Notice how wide the gaps are between the tiles in the center of the water area. Normally, the focal points of the image should have the most narrow gaps in a mosaic not the widest (if there is any variation in grout width).

A No Good Very Bad Day

Caroline emailed me a photo of her un-grouted mosaic for advice on grout color as a lot of people do, but the day she happened to email me was a very bad day at the warehouse, and so I was more blunt in my response than I normally am.

Since the start of the pandemic and Trump’s China tariffs, running a retail business and importing goods and shipping packages has been extraordinarily difficult with all sorts of complications and extra tasks and expenses, but that day was different.

The day Caroline emailed, I think we set an all-time record in terms of petty nonsense and serious problems all coming on the same day.

Anyway, I receive a ton of emails from mosaic novices with photos of first-time mosaics with very wide grout gaps, and they all look bad after grouting, and so my spirit sank when I saw Caroline’s mosaic.

I told her that unless she reworked some of the areas by prying up tiles and setting them more closely together, the mosaic would not look good after grouting.

I didn’t even make my usual recommendation to use dark grout if she chose to go ahead and grout it without reworking it, which is a good indication of how negative my mood was that day.

A Pleasant Surprise

Thankfully Caroline didn’t let my email get her down. She also used a dark-colored grout, which was key to making her mosaic work.

I think the main reason wide gaps make novice mosaics look so bad is that novices tend to use white grout as if they were tiling a bathroom instead of rendering an image.

TIP: Our eyes see cracks between objects as black lines not white, and so using white grout is a surefire way to destroy any verisimilitude your image might have had otherwise and should be avoided -unless you are deliberately trying to make something that looks “crafty” or stylized.

Caroline’s mosaic not only looked a lot better than I thought it could, the part of the mosaic with the widest gaps actually turned out looking the best!

It had me wondering, “Did I know anything about mosaic?”

BUT, look at how this is a special case.

Black Grout

Note that wide gaps in the center of the water don’t look problematic because Caroline used black grout, which not only avoided the problem of white grout, but it also served a visual purpose: dark water between reflecting waves.

All that being said, I am not recommending novices use that as a model. If you need black water between reflecting tiles, use black tile to render it and avoid wide gaps.

The reason I say that is because wide gaps in other places in your mosaic are likely to be problematic.

This is one of the few mosaics I have seen where a wide grout gap didn’t have a absolutely fatal impact on the image being rendered:

Sunset Mosaic Backsplash, grouted. Oh my goodness, look at how “real” the water looks with sunlit waves separated by dark water (grout) with the lanes of orange color at either side. The part of the mosaic I was most concerned about looks the best!

TIP: Concerned that dark grout will make your mosaic look dark? Simply make your grout gaps narrow, and it is not an issue. Don’t try to rationalize wide gaps or light grout based on theme or subject if your goal is to make an image that looks like real life.

Installed Mosaic

I think that the installed mosaic looks good.

Looking at the dark lines in the sunrays, I think I would have liked it if the mosaic had used the same dark/black grout in the sunrise and land areas.

Stove Mosaic Backsplash, installed







14 responses to “Mosaic Grout Rules”

  1. Janet Sacks Avatar

    Great article!! Thank you so much.

  2. Claire Lavin Avatar
    Claire Lavin

    Caroline’s mosaic shows her experience as a designer. Had she used dark grout throughout the design, the depth would have been greatly diminished. The focal point would have been lost. Good choice! Using two colors of grout takes practice. It’s not easy to use dark and light grout.

    1. Jill Gatwood Avatar

      I agree. I would have used a dark grout throughout, but her use of lighter grout in the sunburst area gives it a contrasting, lacy look. I teach mosaic art classes and I have learned so much from beginners who ignore my advice and go against my recommendations and sometimes end up with a surprisingly beautiful piece.

      1. Joe Moorman Avatar
        Joe Moorman


  3. Susan Cravey Avatar
    Susan Cravey

    I think it is stunning!

  4. Sandra Gildroy Avatar
    Sandra Gildroy

    Beautiful work! I like the lighter grout above as it seems to separate the new morning’s light from the still darkened water making it realistic.
    Sandy Gildroy

  5. Nicola Jesse Avatar
    Nicola Jesse

    That is amazing .Love the use as a backdrop! I love incorporating the Sun and yours is inspiring. I’m planning a Lisbon piece! Such a sun filled country.

  6. yolanda k bergman Avatar

    Are there any online courses on how to make kitchen backsplashes?

    1. Joe Moorman Avatar
      Joe Moorman

      I’m not sure about videos specific for mosaic backsplashes, but a backsplash isn’t any different from other architectural mosaics on walls.

  7. FRED GENCHI Avatar

    Joe: Yes, the piece came out just stunning. I do have a suggestion: Would you do an article on using two different grouts on the same art piece? Something quite detailed as to how the line of demarcations are performed as to eliminate a choppy result.Always look forward to your articles. Regards, Fred Genchi (Esmont, VA) 8/6/22

    1. Joe Moorman Avatar
      Joe Moorman

      Hi Fred,

      Jill Gatwood might be a better person to ask about that. My approach is to keep grout gaps small enough that they don’t have a significant impact on color. That being said, people email me studio photos all the time, and if I get some that show how they managed those borders, I will definitely post about it.

      I’m fairly certain that one grout has to be hard before other grouts are applied in later sessions. I’m not sure how effective taping off areas would be for making crisp transitions between zones. I suppose that some amount cleaning out the grout gaps at the edges is required before other color grouts are applied.

      1. Claire Lavin Avatar
        Claire Lavin

        YES to your comment about the grout line edge needing to be dry and perfectly defined before adding the second color. I use a pallet knife to straighten the edge and insure the grout is packed down securely along the edge. When it is dry, I hit it with an inexpensive matte sealer that dries clear. This makes it easy to clean if the second color should jump the line.

        1. Joe Moorman Avatar
          Joe Moorman

          Hi Claire,

          Thanks for your very useful comment. I was hoping people with experience doing multiple grout colors would chime in with tips like that!

  8. Julane Stites Avatar
    Julane Stites

    Interesting article…Just goes to show the endless learning that most accomplished artists confess to.

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