Tag Archives: garden mosaic

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.

 

How To Mosaic a Patio Table

Replace Glass Top With Concrete Board

Glass-top metal patio tables can be used to make a mosaic table by replacing the glass top with 1/4 inch concrete backer board. The concrete backer board is roughly the same thickness as the glass top it is replacing, and it can rest on the rim of the metal table just as the glass top did. However, the thin concrete backer board can sag if unsupported, so marine plywood or pressure-treated plywood should be laminated to the underside of the backer board to stiffen it.

Note that the plywood should be slightly smaller in diameter than the concrete backer board so that it doesn’t interfere with the metal rim of of the table. Only the concrete backer board rests in the inside of the rim where the glass rested. If the plywood were to rest there, then the table top would be too thick and stick up above the rim instead of fitting inside it like the glass.

Steps For Replacing The Glass Top With Reinforced Concrete Mosaic Backer

  • buy 1/4″ concrete backer board from building material store.
  • measure glass top being replaced.
  • cut 1/4″ concrete backer board into a circle the same size using jig saw.
  • cut pressure-treated plywood into slightly smaller circle using jig saw with fresh blade.
  • glue plywood to concrete backer board using Weldbond or other PVA glue.
  • paint underside of plywood and its outer edge with multiple coats of outdoor paint.
  • insert table top into metal table base.

Repairing Edges of Concrete Backer Board

Concrete backer board sometimes has bubbles and voids that aren’t exposed until you cut across them and leave a weak spot or rough crumbly spot at the edge of the piece. You can also damage the edges of the concrete backer board during transport and handling. If this happens, you can repair and reinforce these weak crumbly places with the same thinset mortar that you use to attach the tiles.

Use Thinset Mortar Instead of Glue

Outdoor and wet mosaic should always be done with thinset mortar instead of glue. Thinset mortar is concrete with polymers added for strength and adhesive properties. You can also use the thinset for grouting the finished mosaic. An outdoor mosaic made with thinset will last many times longer than a mosaic made with glue, and that is why they use thinset for attaching tiles in swimming pools.

Using Thinset

We use Versabond brand thinset by Custom Building Products and add 1/4 pound of water per pound of thinset. Thinset comes in big bags that are inconvenient. We keep the bag of thinset in a 5-gallon plastic bucket with a lid. We slide the whole bag into the bucket and cut the top off the bag and scoop out what we need. Never try to pour it unless you like big clouds of dust that is dangerous to breath.

Finding The Right Table Is Easier Than Making The Wrong Table Work

I have always disliked the subject of mosaic tops for metal patio tables because I receive too many emails from lunatics who think the most important thing about the table to be mosaiced is that it is what they already happen to have on hand. It doesn’t matter to them if the table is broken or rusting to pieces or made of wood or already has an expanded metal mesh top welded in place.

For these people, it isn’t about finding a table that is appropriate for a mosaic top, it’s about making whatever they happen to have work, no matter how flawed or problematic or downright dangerous it might be. What’s worse is that when I take valuable time to email back explaining why the table is a poor candidate, they usually email back proposing some farcical method of making it work and wanting further comment.

These proposals show a lack of understanding of basic concepts, but what really makes them insufferable is that they are usually posed as questions asking me to explain why it would not work or why it wouldn’t make the process quicker or easier, usually in a pleading way. (As if my agreeing with them could somehow alter laws of physics or other aspects of objective reality… )

Reading their emails always brings to mind an expression used in the military, one that is blunt, crude and profoundly apt, like so many military expressions: You cannot polish a turd. How many times have I longed to type those words into an email reply!

Inspect Table For Strength And Stability

A mosaic table top can weigh significantly more than the glass top it is replacing. Before doing anything else, inspect the table to make sure it can hold the weight. Look for broken welds in particular, but also keep an eye out for the gauge of materials used for the table. Most metal patio tables are much heavier and stronger than they need to be, but factories make things lighter, cheaper and more disposable each year. If the table in question appears to be light-gauge and weaker than most wrought iron you have seen, then think twice before using it as the base for a mosaic table top.

Bistro Tables

If you use a small metal bistro table, then make sure that you don’t create a safety problem by putting a very heavy top on a table that is taller than it is wide. This can make the table unstable and easy to tip over. The heavy table top could easily injure someone if the table were knocked over by a casual bump. The solution is to anchor or weight the feet of the table, and a sock filled with sand and tied in a knot is often all that is required. Using wire to twist tie the table to the railing of a balcony is another quick solution.

Glass Mosaic Tile Is Best For Outdoors

Glass in nonporous and therefore impervious to moisture and freeze damage. Ceramic tile and stone are porous, and thus water can penetrate inside and freeze and crack the tile over time, sometimes very rapidly depending on where you live. Sure we have a lot of Roman stone mosaics from 2000 years ago, but those mosaics are in the dry warm Mediterranean basin and not west Michigan…

Remember To Seal Outdoor Mosaics

A few days after grouting, you should seal your mosaic with a tile and grout sealer. Tile and grout sealers are invisible pore sealers and not coatings that form a separate layer over the top of the mosaic. You wipe them on with a rag, and then wipe away the excess with a clean rag and allow to dry for ten minutes. Apply it 3 times or whatever the manufacturer instructions recommend.