Techniques of Community Mosaics
by Olivia Gude

An intergenerational team of volunteers creates the mosaic panels for a public art seating installation in Covington, Kentucky.

Collaboratively designed and executed mosaics offer the opportunity for community members to contribute their ideas, skills, talents, and labor to making a permanent symbol of community strength and potential. For durability and safety, it is important that the mosaic project conform to good practices concerning tile and tool selection and methods of installation.

Let’s begin with an overview of traditional methods of making mosaics and see how these methods have been adapted by the community mosaic movement so that they are suitable for relatively unskilled (but enthusiastic) volunteers to participate in making a high-quality community artwork.

Direct Method

Artists Catherine Cajandig and Concetta Morales led a group of teens in using the direct method to create the mosaic, Roberto Clemente: a Man of Pride and Honor in 1985. Ceramic pieces were glued to plywood panels that were then installed on the wall.

Use graphite or chalk to draw the design onto a properly prepared wall or cement board that will later be installed as a single piece on the wall. Nip each piece of tile to the desired shape and glue it into place on the surface using an appropriate adhesive. (CPAG recommends mastic for indoors and thinset cement for outdoors.) Allow tiles to set in the adhesive for the designated length of time. When the tile work is completed and adhesive is dry, rub grout into cracks between tiles, and wipe the surface clean.

I don’t usually recommend this method for complicated mosaics because it’s a mess when participants get the adhesive on the surface of the tiles, on their hands, and on the nippers. It can be time consuming and difficult to clean adhesive off the surface of tiles. Cement and other adhesives may require that the participants wear gloves, making it especially hard to handle small pieces of tile. Because people are usually working vertically and on top of wet adhesive, they can’t easily experiment with nipping the shape, testing it in place, and then nipping again to get just the right shape. Usually, the quality of the tile work is not as refined and interesting as that done by the indirect method. Another deterrent to quality is that because the tiles are set one at a time, the mosaic director can’t critique the work and suggest or incorporate small changes before the tiles are permanently affixed.

A diverse group of differently abled volunteers worked with artists Tracy Van Duinen and John Weber to create this bricolage-style mosaic directly on the wall in 2003.

Recently, Chicago Public Art Group artists inspired by folk art practices and a visit to Isaiah Zagar, a master of direct mosaics in Philadelphia, have been experimenting with loose, more freely drawn mosaic works combining various kinds of tiles and hand painted ceramic pieces. Working in this way, tiles are broken and placed into buckets. Tiles are not cut or carefully fit. Adhesive is applied to the tile as it is taken from the bucket and attached to the wall. Participants outline and fill large, simple areas. After covering areas with large tile pieces, small tile fragments are filled into gaps between tiles.

Chicago Public Art Group is referring to these as Bricolage Mosaics, using the French word that designates making something out of many disparate elements.

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Traditional Indirect Method

Cynthia Weiss and Juan Chávez designed the mosaic Se Hace El Camino Al Andar—We Make Our Road As We Go for Christo Rey High School in Chicago in 2002. The smalti glass tilework was executed by Travisanutto Mosaics in Spilimbergo, Italy. The finished sections were installed by local professional tilesetters.

In this variation of the indirect method, used to create many of the classic Italian mosaics, pieces of smalti (small, thick chunks of glass) are cut with a chisel. A full-scale drawing on the table is covered with a sheet of clear plastic or glass. Laid on top of this is a fiber or plastic mesh. Individual tiles are glued to the mesh with cement, face side up. The piece is grouted while on the table and then carefully packed and transported to the installation site for affixing to the wall with cement. This method requires the use of carefully-fit thick glass tiles, set by highly trained mosaic workers and installers. It is not well suited for volunteer-based community mosaic projects.

In another variation of the indirect method, the piece is created upside down on the table. Draw the design full-scale and backwards—as seen in a mirror—on heavy paper. Nip pieces of tile to the desired shape and affix them finished surface down onto the paper with water-soluble glue. When the work is completed, cut the design into manageable pieces (about one foot square) and carefully label each section (A1, A2, A3, B1, B2, etc.). Cut shapes that will fit together like puzzle pieces.

Attach sections to wall with appropriate adhesive. Allow tiles to set in the adhesive for the designated length of time. When adhesive is dry, use sponges to dampen the paper with water. Remove the damp paper from the surface of the mosaic. Scrape out excess adhesive that is above the surface of the tiles. Work grout into cracks between tiles and wipe the surface clean.

These methods are called “indirect” because the tiles are first assembled off-site and are not adhered directly to the wall. An important advantage of this method is that the tile work is done at tables in the studio, thus allowing more control of the cutting and placement of tiles. Because one is placing the tiles on the paper upside down, this method is most suited for use with tiles that are colored all the way through such as glass or unglazed, colored porcelain.

A disadvantage of all methods that make use of paste, glue, or cement when placing the tiles is the mess on tiles, hands, and tools when participants are shaping tiles and affixing them at the same time. An aesthetic problem when working “upside down” is that color and tile work choices are made while looking at the artwork backwards.

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Contemporary Indirect (Face Up) Method

The Lowell Centennial Mosaic was designed and created by Olivia Gude, Beatriz Santiago, and Juan Chávez with teen artists using the contemporary indirect method.

Draw the design full scale and face up on good quality paper. Some artists use a heavy weight paper; others prefer to use gridded or ungridded vellum. Cheap white roll paper is not suitable because it has a tendency to tear when tiles and tools are repeatedly placed on its surface. It also has a tendency to wrinkle and pucker when it absorbs even a small amount of moisture from hands resting on it. Paper must be taped tautly to the tabletop. Tape all edges because it is very disruptive of smooth mosaic making if little pieces get under the paper.

Tiles are nipped and then laid out on a full-scale drawing. As sections are completed, they are fixed into place with clear plastic adhesive film.

Nip pieces of tile to the desired shape. Lay the pieces onto the paper. Continue adding pieces. When necessary, shift tiles that are already laid to achieve a better design or a more accurate outline. After completing a section of tile work, very carefully cover the section with clear plastic adhesive film such as Protecto Film (for light weight glass tiles) or Can-Do Tape (for heavier ceramic tiles.) See the Resources chapter for sources. Once the plastic adhesive film has been lightly “dropped” into place, smooth the film gently and firmly onto the tile. Trim the film so that it is not sticking over the edge of the tile work onto unfinished areas.

As you finish each new section, apply plastic film to the new work and overlap onto the finished work. When completed you’ll have a mosaic held together by many overlapping sheets of plastic film. Cut the finished mosaic into manageable pieces (about one foot square) and label each section (A1, A2, A3, B1, B2, etc.). Cut shapes that will fit together like puzzle pieces to ensure correct alignment.


Because the mosaic was created in thin, glass tiles and the brick wall had deep joints, the installers began by creating a smooth concrete bed on which to install the mosaics with thinset cement.

Attach each section to wall with appropriate adhesive such as mastic or thinset. (See installation information below.) Allow tiles to set in the adhesive for the designated length of time. When the adhesive is set, gently pull the plastic film off the tiles. Occasionally, a tile may come loose with the plstic film. As you proceed, scrape out the dried adhesive and reaffix each loose tile with a bit of fresh cement or mastic. When all the plastic film is removed, examine the mosaic carefully, and scrape out excess cement or mastic that is above the surfaces of the tile. Work grout into cracks between tiles and wipe the surface clean.

Wait until the adhesive is completely set before removing the plastic film. On a hot day, cement will easily be set enough by the next day. In a cool interior space in winter, you may wish to wait several days for the adhesive to be fully dry.

There are many technical and, consequently, aesthetic advantages to working in the indirect method, particularly when making a community mosaic. As in traditional indirect methods, the tile work is done at tables in the studio, thus allowing more control of the cutting and placement of tiles. It is easier for the mosaic director/community artist to teach participants and monitor the quality and progress of the work. The mosaic is worked face up, therefore, participants do not need to try to visualize how the design will look when flipped over.

There is no mess with paste or cement at the tessellation table. Participants can concentrate on the shape of individual tiles. An important advantage of this method is that tiles can be repositioned as the participant gradually develops an area. The mosaic director can suggest or make needed changes before affixing the tiles with the clear plastic adhesive film.

This indirect method allows many people to work on different segments of a mosaic simultaneously People of various physical abilities can work on the project. The completed artwork can be installed in interesting, dramatic, and difficult-to-reach locations by a small number of skilled professionals and volunteers.

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Designing a Collaborative Mosaic

Begin by explaining the idea of a collaborative design process in which various people’s ideas are developed and intertwined. Use brainstorming, guided meditation, preliminary drawing exercises, and discussion to explore possible themes for the mosaic. Visit the proposed site of the mosaic. Discuss the feelings you get at this place now and how you want people to feel after the new art is installed.

Give participants miniature scale drawings of the site. Have each person draw in his or her initial ideas about what should be in the mosaic. On another miniature scale drawing, have participants create abstract designs that explore the relationship of the forms in the mosaic to the rest of the site. Compare and discuss these results.

Do visual research. Use the library, internet, or local history sources. Gather information and images. Draw and collage. Refine and recombine each other’s work. Collage together ideas. Design at a scale of 1” equals 1’. This will prevent people from drawing tiny little details that would be difficult to make in tile. Collage various drawings onto a single sheet.

After developing the design for The Continents mosaic, each student did a colored pencil drawing showing a possible color scheme. Later their ideas were combined into the final color scheme for the tile piece.

When you have decided on the final design make a crisp line drawing of the pasted together design. Use a copy machine to make a small version of the final drawing. Give these out to the participants and ask them to use colored pencils to explore possible color schemes. If you already know the color of your tiles, only give out colored pencils in those colors. Discuss color schemes. Be sure to experiment with reversing which areas are light and which are dark.

Unexpected value contrasts often create the most dramatic hue/value effects. Combine ideas from various color schemes.

Make a small transparency of the drawing. Use an overhead projector to project it at the correct full-scale onto large paper taped to the wall. Trace lightly.

The full-scale drawing for What Do You Need to Know? was drawn on gridded vellum paper. Guidelines within each shape helped participants create various patterns of tilework.

Darken the lines on the full-scale mosaic drawing, refining, smoothing, and adjusting as you go. Use actual tiles to help determine the sizes of various parts of the design. For example, if there is a border around an area, try to make the border the width of 1 or 2 full tiles, rather than 1 3/4 tiles, requiring lots of cutting and a less crisp edge.

Make a pattern of the overall shape of the mosaic on thin paper. Cut this out and fit it to the actual site. Make size adjustments to the main drawing as necessary. This step, completed early in the project, can save lots of frustrating re-cutting and fitting later.

When making the actual mosaic, be open to changes and fresh ideas. Try to plan places in the design in which participants can experiment with unexpected details or unusual tessellation patterns.

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Use the best quality tile nippers you can find or afford. There are many styles of nippers. Experiment to find a nipper style that works well for you and for other project participants. In general, nippers with carbide tips are more expensive, remain sharp longer, and are more effective especially when cutting glass or porcelain. Nippers must have a spring or you will wear out your hand flipping open the nipper after each cut.

Sax Arts and Crafts usually carries a suitable carbide-dipped, spring-loaded nipper. Delphi Stained Glass also carries a variety of mosaic tools. Check with local hardware and tile stores. Because these are not official art supplies, it is sometimes possible to get a community donation of nippers from a business. Quality nippers will cost from $20.00 to $35.00.            

Even high quality nippers wear out after being used continuously for 1 or 2 months. It is not possible to sharpen carbide-tipped nippers yourself, but a high-grade machine shop might be able to do this for you. There are also brands of nippers in which the carbide tips can be replaced. Sadly, it is usually necessary to discard the nippers and purchase new ones.

It is good safety procedure to wear goggles when nipping tile. Many participants do not like to wear goggles and nip tile chips onto the floor, minimizing the chances of tile chips getting near their faces. Inexpensive plastic goggles are fine, but they tend to get scratched and become useless unless a storage system is devised that prevents them from rubbing against each other or being laid face down and scratched from tile fragments on the table.

Other Tools for the Mosaic Studio

Along with basic art supplies, other items that are useful to have in the mosaic studio are lots of sturdy tables, colanders for draining and washing tile (when it needs to be removed from backing sheets), scissors and snapknives to cut adhesive film, bandaids for the occasional pinprick cuts from tile fragments, wide masking tape to hold drawings to the table, plastic shoe boxes or dishpans to store tiles, shelves to store the boxes or dishpans, plastic plates with multiple sections to keep several colors of tile handy in a work area, tweezers to grab tiny tile pieces, clean 2 or 3” paint brushes to brush fragments off the mosaic table into a dustpan, and several brooms.

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Nipping & Nibbling Tiles

To shape a tile, hold it with one hand, with the other hand, place your nippers on the tile. Position the blades so that they overlap the tile by only 1/8” to 1/4”. Press handles together—quickly and firmly. The tile will easily snap.

Angle the nipper’s edge in the direction that you want the tile to snap.

In the beginning, your most likely mistake will be to put “too-much-nipper” on the tile. When you put too-much-nipper on the tile, it takes a great deal more hand strength to press the handles together. Remember your goal is not to cut through the tile; your goal is to cause the tile to snap.

The angle of the snap is determined by the angle of the nippers on the tile. If you are trying to make a straight-cut, be sure that your nipper blades are perfectly in line with the edges of the tile. Many tiles have striations on the back—make use of these by holding the tile in such a way that the striations encourage the direction of snap you want. If you are trying to create an angled-cut, tilt the nipper blades in that direction.

Often the tile will snap in approximately the right way, but the edge will be jagged. Now you will use the technique of nibbling. Think of the nippers as teeth and gently gnaw or nibble away little bits of tile until you get a smooth line. Trying to take off too much material at once is likely to cause a snap that will fracture your desired shape and you will have to start nipping a new tile.

Curves are created by nibbling. Use a number of nips to create the approximate shape. Then gently nibble away until the desired curve is created.

Beginners error on the side of impatience. They will often become frustrated with their jagged cuts and assume that when they are more experienced they will be able to create a perfectly shaped tile in a few nips. The converse is actually true. Experienced mosaic artists often make many tiny nibbles on a tile to achieve just the right shape. Rough sandpaper can also be used to refine the edge of a cut tile.

Other methods for shaping tiles include:

  • using a glass cutter to score the surface of the tile to encourage the tile to snap in
    a particular way
  • a snap cutter machine, that scores a straight line on a tile and has a lever to use for snapping
  • expensive (and potentially very dangerous) electric wet saws that circulate water to cool the blade as it cuts the tile.

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The beauty of mosaics lies in the variety and inventiveness of the tile work. In good basic tessellation technique, tiles are carefully fit together so that the surface is mostly tile with little grout--it’s the tiles that are beautiful and colorful, the matte grout is only a framing accent.

Set up your mosaic tables so that people can work from different sides. It can be helpful to use the flat blade of a “snap knife” to nudge a tile into the perfect location.

Great mosaic work often uses different styles of patterning within the mosaic to create interesting formal contrasts or to reinforce the imagery of the work. Collect interesting tiles in various shapes. Study traditional and contemporary commercial and community mosaics to develop ideas for your personal tile style. (See the Mosaic Aesthetics: Tessellation and Composition chapter.)

When laying ceramic tiles, it is best to lay tiles around the edge of a form first and then to fill in the area. Some artists use only factory edges of tile on the edges of color areas in order to set off the shape in an attractive and finished-looking manner.

When laying small glass tiles, plan a tessellation pattern related to the size of a single tile and work from one edge to another. Try to avoid ending with a tiny tile—it’s ugly and can be easily lost in setting and grouting. Sometimes one has to go back several tiles and intersperse several 3/4 size tiles to avoid ending with an awkward sliver.

Several years ago, I noticed that I was teaching two different kinds of skills at once in introductory mosaic training workshops. I was trying to teach people to decide what shape they needed to cut at the same time I was teaching them how to cut. The first results would often be lumpen, amorphous shapes—not only because the participant did not have the physical skill to cut the desired piece, but also because the participant did not yet have the perceptual and design skills to decide what pieces were needed.

I now break training workshops into two separate components. In the first, I work with paper tiles and we concentrate on understanding the geometry of various tessellation choices. Participants learn to plan a tessellation strategy and then execute it in paper tiles. This exercise may take a couple of hours. Later, when participants learn to cut tile, they can concentrate on the technical aspects of trying to create various shapes.

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Traditional mosaics are usually created with natural colored stone such as marble or granite or with colored glass smalti. Tesserae (tiles) are created by using a hammer and chisel to break the slabs of colored glass smalti into small chunks. Smalti comes in an almost infinite variety of colors, is quite expensive, and must be worked using traditional indirect methods.

Most community mosaics are made with commercial grade tiles. There is a wide variety of commercial tile available. Most contemporary artists choose to use either glass or ceramic tile in a given work, though occasionally artists combine ceramic and glass in one work with good effect. Tiles often come in grids adhered to sheets of paper or plastic mesh. When tiles are adhered to paper, they must be soaked and rinsed. Tiles adhered to mesh must be pulled off the mesh by hand.

Color Choice

The goofiest thing an artist ever said to me about his mosaic work: “It would have been better, but I didn’t have the colors in my design.” Hello? That is like saying that you would be a better chemist if the elements were different. Even with careful searching and a big budget, color choices in tile will be somewhat limited. Design work that looks good in the color tiles that are available. 

Dare to limit your palette. Try not to be swept away by hue contrast. Mosaics that also incorporate dramatic value contrast tend to be more effective, especially at night.

Glass Tile

Mosaics done with glass tile tend to have a more elegant formal look. There is a greater range of colors. It is possible to create effects similar to traditional mosaics when using glass.

Glass tiles (sometimes called Venetian glass) are usually small 20 x 20 mm (about 3/4 inch square.) and approximately 5/32” thick. They are relatively expensive ranging from $7.00 to more than $30 per square foot. Bisazza Mosaico is a popular brand with Chicago mosaicists. ttp:// Because Bisazza requires orders to be made in full boxes, it can be prohibitively expensive for use in a small project.

Artists often use tiles from various sources in a single work because this gives them a broader range of subtle color choices. Label tile sheets or containers with the manufacturer, name or code, and year. Sometimes different color lots can give you added shading potential.

Art supply stores and art education vendors re-package and sell the same or similar tiles as described above with a high mark up. There are now on-line dealers who sell small quantities at what seem to be relatively decent prices. Mosaic Mercantile, a good source for small quantities, can also work out discounts for artists placing large orders.

Ceramic Tile

Ceramic tile can be gotten from many sources. Locating and collecting interesting tiles at good prices is part of the art of mosaic making.

Purchase tiles at commercial tile stores. Try to find a “high end” store that carries many kinds of tile. Study the sample books. Identify tiles that fit your color needs and price range. Also, find tile outlet stores in your area. Visit them frequently. Stock up on unusual shapes or patterns. Become a tile collector.

If you are creating a mosaic for a school or non-profit organization, explore getting donations from retailers, manufacturers, or tile setting companies. Beware. Sometimes artists plan to create a community mosaic solely with donated tile. It is often difficult to get a good color range with all donated tiles.

Locate a supplier who will sell you basic, colorful 2” to 6” square tiles. Often on-sale tiles are only $1.00 to $4.00 a sheet. Tiles such as “Fiddlesticks” by Latco are thin rectangles (1/2’ by 2”) shapes. They’re useful for creating lines.

Mixing a number of different kinds of tiles can create interesting effects in a mosaic. However, if tiles of various thicknesses are used, it is important that these be in clearly demarcated separate areas. Variations in thickness can make installation and grouting more complicated.

Ceramic tiles that will be used in outdoor mosaics must be frostproof. See below for more information.

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Vitrification = Frostproof

Tile used in outdoor installations must be fully vitrified. This means that the material is fused into a hard, glasslike substance that does not absorb moisture. Glass tile does not absorb moisture and so it is suitable for exterior applications.

Ceramic tile comes in a wide range of clays and so it is important to carefully assess whether it is suitable for use outside. In a fully vitrified tile, the choice of clay and the temperature to which it has been fired and the length of firing has created a material in which the particles are densely packed and hence it does not absorb moisture. When inappropriately porous indoor tiles are used outside, the tiles absorb a high percentage of moisture. When the temperature drops to freezing, the water in the tile freezes and expands. The tile shatters and cracks and its glaze flakes away.

Check the manufacturer specifications for new tile that you purchase. It should be rated by the manufacturer as frostproof. This is the way to be 100% safe in your tile choice. In most cases, high fire porcelain tile is suitable for outdoor use. Check what architects in your area use for storefronts, highway underpasses, and swimming pools.

Sometimes one gets remaindered or donated tile or tile produced in other countries for which one cannot obtain technical information. Experienced mosaicists use several informal methods to determine the suitability of such tile. An effective and unsavory technique is popularly known as the “lick test.” Lick the unglazed back of the tile. If your tongue sticks to the tile, it’s definitely not frostproof.

Other methods to determine the frost resistance of a tile include painting water onto the unglazed portion of a tile and seeing if it beads or is absorbed. The pitch of the sound made by two tiles when they are tapped together is also an indicator. A high-pitched sound suggests that the tile may be frostproof. Try these methods with tiles that are certifiably frostproof so you understand how a frostproof tile looks and sounds.

Another method some people use to check a tile’s ability to withstand freezing is to place the tile in a saucepan of water. Bring the water to a boil. Cover and continue to boil and soak for an hour. Remove the tile from the water and let it cool. Place the tile in the freezer overnight. If it doesn’t shatter, the tile is likely to be frostproof.

There are methods to measure the exact degree of porosity of a tile. It involves weighing a dry tile on a finely calibrated scale, soaking the tile in water for a period, and then weighing again. This procedure is described in detail in many standard ceramics texts.

If one is incorporating handmade ceramic tiles or other elements in a mosaic, it is crucially important that these meet these tests of being frostproof. Check with your local clay supplier. They are usually fonts of information concerning the most appropriate clay body, firing temperatures needed to achieve vitrification, and compatible glazes.

It is also vital that ceramic construction techniques be carefully monitored when using handmade elements. Even a frostproof object will come apart over the winter, if portions of it were simply pressed together rather than being sturdily scored and slipped into a single piece.

A Community Arts Mosaic Nightmare    

My saddest community art memory is of arriving at a high school and seeing the messy, smeared remnants of mastic adhesive on the brick walls facing the outdoor stairway at the main entrance to the school. An inexperienced artist had tried installing tiles in frigid weather with an adhesive intended for indoor use. When the glue failed to set after several days and many tiles had been accidentally moved or knocked off the wall by passing students, some rowdy boys destroyed much of the rest of the mosaic deliberately. The principal ordered the rest of the tiles (still loose from unset mastic) be removed—leaving a gooey brick wall as the only testament to community strength and creativity.

Even if the mastic had been used in warmer weather and had set properly, the adhesive would have soon begun to deteriorate because of the effect of moisture and frigid temperatures. After a few years, the adhesive would have crumpled and the tiles would have begun to fall off the wall. However, even if the correct adhesive had been used, the tiles would have exploded during the first winter because they were porous ceramic tiles that could not withstand freeze/thaw cycles.

For this doomed project, the question wasn’t if the project would survive, it was how short would its lifespan be. This is a cautionary tale. Plan. Do your research. Consult tile professionals in your area. Don’t let a community arts disaster happen to your wonderful project.

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Technical Considerations for Installation

A mosaic can be a stunning, permanent addition to a school or community site symbolizing the strength, talents, and creative energy of the community. An improperly made mosaic can be a maintenance nightmare and communicates lack of skill and the inability of community members to positively shape their environment. There are even safety concerns because tiles are quite heavy so an improperly installed mosaic can literally fall off the wall and cause serious injury.

Mosaicist Mirtes Zwierzynski holds up a sheet of glass tile held together by clear plastic adhesive film as she prepares to set the tiles permanently with thinset cement.

In my basic description of direct and indirect fabrication processes for mosaics, I cautioned that mosaics must be installed on “a properly prepared wall” with “appropriate adhesive.” Neophyte mosaicists sometimes feel frustrated that they can’t get a single definite answer about the best materials or methods to use. In this brief article it is difficult to explain the variations of material which should be used depending on the situation, but I can give some overriding principles and clear direction on how to ascertain the technical information you need to make your project safe, permanent, and beautiful.

The simplest technical rule for making permanent mosaics: the structure which supports the mosaic, the preparation of the surface, and the tiles, adhesive, and grout should be of a quality approved for your particular situation by an experienced local tile setter.

Get to know tilesetters in your area. They can advise you on the technical requirements needed to create your mosaic. It matters if the support is metal, wood, concrete board, or plaster. It matters if the mosaic is installed under a continuously running fountain. It matters if the mosaic is outside. It matters if the mosaic is on the floor. An experienced tilesetter can help you with the basic information you need to make the correct material choices. Check with a few different people and see if the information jives. Older tilesetters have often been through rigorous apprenticeship programs in which they learned special skills for handling unique tile installations. 

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Indoor Mosaic Installations

The installation for these is simpler and less demanding than outdoor mosaics. Almost any tile can be used on walls. Tiles used indoors are often softer and easier for students to shape. The mosaic support (usually a wall) must be firm and free of dirt or chipping paint. Often it is best to scratch through the paint so that at least some of the adhesive adheres to the underlying wall, especially if the wall has been painted with a glossy paint. (Students seem to love to attack walls with screwdrivers or snap knives so it is easy to get volunteers for this job.) Sometimes a special undertile primer is the best choice for wall preparation. Mastic or other suitable indoor tile adhesives can be used. Depending on the look you want to create, almost any grout will be suitable.

After the tiles were set on the wall with mastic with the help of a professional installer, high school students engage in the time-consuming and detail-oriented task of removing the adhesive film and removing any bits of mastic that have come to the surface between tiles.

The basic method of setting tile is to evenly spread adhesive on a portion of the surface with the unnotched edge of a trowel. Then use the notched edge of the trowel to “comb” through the adhesive, creating ridges of uniform height. The depth of the notches in your trowel is determined by the thickness of your tile. Use a tool called a “floater” to securely press the tiles into the adhesive.

The goal is to have enough adhesive to attach the tile without excess glue swishing up between the tiles at the level of or above the level of the tile depth.

Handmade pieces should be “back-buttered.” This means to spread adhesive on each tile as well as on the surface.

If you are creating a floor mosaic, check to be sure that the tiles are suitable for floor installation. In areas where the floor may become damp, it’s important to use unglazed tile to avoid dangerous, slippery situations. For floors, we recommend using unglazed colored porcelain; with this tile, you won’t lose color if the surface begins to wear away or chip. Remember that pools, showers, and fountains must be set with cement.


Outdoor Mosaic Installations

Outdoor mosaics must be made of frost-free tile unless you live in a climate that never freezes. In this case “never” literally means never and not almost never. Your area may get a frost only once every 20 years. What a shame if a frost in 2019 destroys an otherwise still perfect mosaic the community created in 2004!

Thinset cement is applied to the wall in small patches and the completed mosaic work is set into the cement. Applying cement to too large an area at once can result in cement drying out and not properly adhering the tiles to the wall.

Most mosaics that are outside are adhered with “thinset cement.” The grout should also be rated for outdoor use. Sometimes outdoor mosaics are set directly on a concrete or brick wall.

When setting over a rough wall, it is often desirable to adhere wire mesh to the wall with masonry nails and to float a smooth bed of cement over the surface. When the cement bed has dried and cured, the tiles are installed with thinset cement. This is a job for a skilled professional.

In Chicago, most outdoor community mosaics are installed with the paid assistance of professional tilesetters. It’s a big job and many hundreds of volunteer hours have gone into creating the mosaic work. It’s important that the installation be first rate so that it will withstand time and weather.

When You Can’t Install Directly on the Wall

In situations where you cannot adhere the tile directly to the wall, divide the mosaic design into shaped sections. Try to create sections along lines that will disappear into the mosaic design, rather than chopping the mosaic up into squares. Cut plywood (concrete board or MDF for outside) into panels for these shapes. Remember to consider issues of size and weight when planning your panels. Install the tiles on the individual panels. Leave out individual tiles where you will need to bolt the mosaic to the wall. In these spots, use a bolting system that is appropriate to the underlying wall to attach the panels. Adhere tiles over the spots left empty for the bolts. (It’s a good idea to keep a bolt map in case the pieces ever need to be de-installed.) Grout the finished mosaic. Finish the edges with tile. On outdoor mosaics, it will also be necessary to seal the edges between the wall and the panels with a silicone caulking.

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Left: Completed mosaic panel held together with adhesive film before installation and grouting. Right: Note how in the installed panel the dark grout emphasizes the patterns of laying the tiles.

Grout is a powder composed of sand and cement that is mixed with liquid to form a creamy paste. Grout fills in the spaces between the tiles and finishes the installation. See the chapter on Tessellation & Composition for a discussion of the aesthetics of groutlines.

When choosing grout, be sure that you have the appropriate mix for indoor or outdoor applications and for the width of your grout lines. Wide grout lines require a stiffer mix.

Color is an individual aesthetic choice. In standard commercial and home tile installations, the grout color and tile color are closely matched in order to create an even field. In art mosaics, it is often desirable to choose unusual colors and vivid contrasts. Many mosaicists love the look of dark gray or black grout setting off the vibrancy of the tile colors.

Contrasting grout creates interesting color reverberations in the completed mosaic.



Grout in similar tones to the surrounding tile tends to de-emphasize tile lines and blends colors together.

After peeling away the surface adhesive film, use a knife to clean out adhesive that is above the tile surface. Dump a pile of grout onto the wall with a trowel and then vigorously press the grout into the spaces between the tiles. The more densely packed with grout, the stronger the joints will be. Use the edge of a grout trowel (a flat trowel with a rubber face), to wipe away excess grout. Clean the surface with a series of damp sponges. After the grout is dry, wipe away the dust with a clean, dry cloth.

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Expand Your Knowledge

Doing mosaics is complicated aesthetic and technical business. We’ve been doing community mosaics in Chicago for over twenty years and we still spend quite a bit of time talking about technical and organizing issues. Have you found a new nipper you like? What caused a few tiles to pop off at such and such a location? Have you seen the latest (colors, sizes, shapes, textures) of such and such tile? How can we get all these folks trained to contribute to this mosaic? What would be the best installation technique in this situation?

Getting to know local professional tile setters and relying on them for technical advise is sound practice. Home repair books and books designed to educate tile setting experts are also good sources of information. Meeting other mosaic artists and sharing information is an important way to stimulate new design ideas and evolve technical knowledge.

Best luck in your tessellating.

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