Mosaic Gazing Spheres

Mosaic gazing spheres are popular outdoor mosaic projects, and they offer a few simple advantages over mosaic-covered concrete lawn ornaments: They are lighter in weight and can be relocated more easily. Also, the mosaic gazing sphere can be adjusted in height easily by changing the height of the display stand used to support them. These are important points if you want to keep the mosaic prominently displayed as vegetation heights change throughout the season. (Think about annuals in flower beds and how high something like black-eyed susans can grow and even hedges can be an issue if you don’t have time to trim them regularly.)

I have instructions for making a mosaic sphere toward the end of this article, but I wanted to mention a few important points first:

How To Display The Gazing Sphere

Wrought iron planter stands that are relatively simple in design make the best supports for mosaic gazing spheres. The ideal type of stand is a circular ring with 3 or 4 legs. You can find these at many lawn and garden centers. Tip: Use a little bit of black electrical tape to wrap the metal ring in four places so that the glass tile doesn’t rest directly on the metal ring. It’s OK for the tile to rest on metal in theory, but eventually someone is going to pick the sphere up to inspect it and not be as careful as they should be in returning it to the stand.

Mirror Tiles

Ordinary mirror cannot be used without a special adhesive that prevents the silver backing of the mirror from oxidizing and turning black. This adhesive is oil-based and relatively expensive compared to thinset. That is why we sell a mirror tile that has a special coating on the back that allows the tile to be mounted with thinset, PVA adhesives and other mosaic glues without turning black over time.

Don’t Use A Bowling Ball

Many people email us asking how to use old bowling balls for making mosaic gazing spheres. Bowling balls make problematic bases for outdoor mosaics for two reasons:

  1. Bowling balls have been reported to expand in high temperatures and cause mosaics to crack and tiles to fall off.
  2. Thinset mortar does not bond to the polymers bowling balls are made from, and thus an epoxy adhesive or oil-based is required, and that means fumes, difficult clean up and shorter working times.

Either of these reasons would discourage me from using a bowling ball as a base even though I like to use recycled and repurposed materials as much as possible.

Where To Get A Hard Polystyrene Sphere To Use

Normal Styrofoam is too soft to use as a base, but there are harder varieties of expanded polystyrene that is ideal: strong, lightweight and bonds to PVA adhesives and thinset mortar. The Plasteel Corporation’s Smoothfoam website sells an 8-inch hard polystyrene sphere. The sphere comes in two halves that can be joined with the same Weldbond PVA adhesive or thinset that you use to mount the tile. Note that you should join the halves prior to mounting the tile, else you are likely to not mount the tile in a way that does not call attention to the seam. There are larger sizes available, but the 8-inch sphere is approximately the size of a standard bowling ball (8.5 to 8.595 inches).

How To Make A Mosaic Gazing Sphere

There is much about making a mosaic gazing sphere that is similar to making a mosaic on flat panel: Tile is attached to the surface using thinset mortar or a white PVA adhesive such as the Weldbond, and after this allowed to harden for at least a day, the mosaic is grouted by rubbing wet grout into the gaps between the tiles.

The Basic Mosaic Process

We have a page of illustrated mosaic instructions for more information about this basic process of attaching tiles and grouting. We also have a page about how to avoid grouting disasters.

Putting Your Pattern On The Sphere

You can draw the pattern of your design onto the surface of the sphere with a Sharpie marker or a pencil. Even if your design is as simple as an abstract pattern of swirls or rings, it helps to draw lines as a guide for each row of tile.

Make sure you position the tile in adjacent rows so that four corners are never lined up together. (You want to avoid positioning your tile in a grid similar to how showers are tiled.) Instead, have the gap in one row coincide with the middle of the tile in the rows to either side. This makes each row stand out, which helps each row suggest motion.

Decide Thinset Or Weldbond

Thinset mortar is generally required for outdoor and wet mosaics. White PVA adhesives such as Weldbond are generally reserved for dry indoor mosaics. However, Weldbond is water resistant when fully cured, and if the sphere is displayed on a stand where it cannot sit in standing water, then a mosaic sphere made using Weldbond could have an extremely long life, especially if it were sealed with a tile and grout sealer.

I have also come to accept that many people are intimidated by working with thinset because it has to be mixed up from powder form, cannot be stored once mixed up, and it is messier to use for a novice.

All that being said, if you want to learn how to do this professionally, or if you want to make absolutely certain that your projects last as long as possible, then you need to learn to use thinset, which isn’t that hard in my opinion. I wrote a page about how to use thinset mortar for mosaic artwork and a blog article about how to keep your hands clean when using mortar.

Decide Which Tile

GLASS is the best tile to use outdoors because it is nonporous and therefore impervious to moisture, and thus it is frost proof. Ceramic and stone have micro pores, and water can penetrate and freeze and cause the faces to flake off. Ever notice how the surfaces of terracotta flower pots start to flake off when left outside over the winter? That is what is happening.

Keep in mind that the Greek and Roman mosaics made from stone lasted because the climate of the Mediterranean basin is dry and relatively mild. If you want your outdoor mosaic to last in temperate and northern climates, use GLASS tile and then grout and seal it.

Each sphere has approximately 1.4 square feet of surface area, so that means you would need:

Of course those numbers assume a grout gap of 1/16 inch. With the 8mm tile, you might want them slightly closer together. Also, if you are cutting the tile, you might want to budget 5 to 10% more to account for cutting scrap.

Grouting And Sealing

Outdoor mosaics should be grouted and sealed. You cannot simply place the tile as closely together as possible. Water can find its way into the tiniest crevice or pore. Consequently, you have to leave a large enough gap (usually 1/16 inch) to ensure that the gap is wide enough to get filled with grout. (As ironic as it sounds, you have to leave a gap to ensure that the gap gets closed up.)

A few days after your grout hardens, you should seal the mosaic with a tile and grout sealer, which are invisible pore sealers that wipe on and wipe off. They aren’t coatings that form a clear layer over the surface. We use TileLab brand that we buy at Home Depot.

One Side At A Time

How do you glue tile to a sphere? One side at a time. Sit your sphere on a folded towel or cardboard box to keep it from moving or rolling as you glue the tile on the upper surface. Rotate the sphere only after the glue has started to set. If you are working carefully to ensure a uniform grout gap, you will probably be slow enough to ensure that the glue is hard enough before you have to rotate the sphere slightly to continue.






13 responses to “Mosaic Gazing Spheres”

  1. […] anything new. For example pique assiette (broken plate) mosaic furniture is fairly common, as are mosaic gazing spheres made from bowling balls. (Note that my article on gazing spheres explains why hard polystyrene […]

  2. Gary O'Malley Avatar
    Gary O’Malley

    I don’t agree with your comments on not using a bowling ball for mosaics?
    I have done about a dozen balls and had them in my garden for over 2 years.
    I use a silastic glue which can expand and it dries clear, just a bit messy on your fingers.

    1. Joe Moorman Avatar
      Joe Moorman


      Thanks for letting me know about the silatic glue used with bowling balls. The reports of problems with bowling balls that I received were from the southern end of California’s central valley, which can have temperature extremes approaching those of the Australian outback. Also, I suspect whether or not you have a problem with a bowling ball expanding in hot temperatures might depend on what materials the bowling ball and its core are made from.

      Please let me know more about the brand of silastic adhesive you were using and what type of climate the gazing stones were displayed in.

      Joe Moorman

  3. Stephanie Erb Avatar
    Stephanie Erb

    What kind of grout do you suggest for this project? Thanks

  4. Krista Avatar

    Can I use glass tile over an existing glass gazing ball that was store bought? I’m thinking of Weldbond or Silicone and then grouting. Thanks! It would go outdoor.

    1. Joe Moorman Avatar
      Joe Moorman

      You should use GE Silicone II. Scuff the ball with a coare-grit sandpaper.

  5. Kathleen Forney Avatar
    Kathleen Forney

    Hello I am working with young students who are covering 4 inch styrofoam balls with weldbond , than glass tiles and finally grout. Will the weldbond work or should I use an industrial glue? We have an abundance of 4 inch styrofoam balls and want to use them . thank you Kathleen

    1. Joe Moorman Avatar
      Joe Moorman

      A white PVA adhesive such as Weldbond is an ideal glue for expanded polystyrene. I’m not sure what would be better.

  6. Frea Avatar

    Do i need to :
    1. First Seala polystyrene ball – then cover with adhesive tape- before painting with thinset
    2 when dry mosaic with glass tiles

    1. Joe Moorman Avatar
      Joe Moorman

      Hi Frea,

      You would not need to seal the polystyrene, and you would not cover with adhesive tape.

      Thinset hardens by binding water not by drying.

      I would read the articles and tool instructions closely.

  7. Liz Avatar

    Any suggestions on making a gazing sphere solar light for outside? Do you think instead of Smoothfoam a clear glass ball is used? And where to find one!

    1. Joe Moorman Avatar
      Joe Moorman

      I’m not familiar. I might use a fish-bowl or some improvised glass vessel.

      1. Melissa Avatar

        Love the upside down fishbowl idea!

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