How to Do Mosaic Stained Glass – The Indirect Method

 There are two basic methods to mosaic work - the direct method and the indirect method or sometime called the reverse or stone method. In the direct method, the pieces of material are directly fixed right side up onto a base and then grouted. In the indirect method, pieces are temporarily fixed right side down onto a removable backing which holds the design together. This is then either placed in a mold and filled with cement or pressed into a prepared adhesive bed. Once the cement is set, the stone is turned out from the mold to reveal the design, right side up cast in the cement. In the case of an adhesive bed, the backing material is removed to expose the design, right side up which is then grouted. Another option is to place the prepared design into a mold which is then filled with mortar/cement.

 The advantage of the indirect method is you create a very smooth, flat surface. You can also create and assemble the design in one place ahead of time, and then install it in a different location later. The disadvantage is that the design must be assembled face down before applying it to the base or casting in the mold. This often requires extra steps in the design or assembly process.

Selecting Tesserae

Tesserae are the individual pieces of material you will arrange to form your mosaic. Most people think of those little square pieces of tile seen in early Roman mosaics or in swimming pools. Today the term applies to anything pieced together to form a design. When working in the indirect method, you must consider how the depth and shape of some items will affect their appearance in the mosaic. Items that are spherical or have a high relief do not rest flat against the removable backing. When cast in a mold, only the portion that is actually fixed flat to the backing will show unless you take steps to protect the curvature of the object. For that reason, indirect mosaics are generally made with tesserae that have a relatively flat front surface.

venetian tile, gold leafed tile, smaltiTraditional Tile Tesserae

Ceramic Tile

stone pebbles for mosaicNatural Stone

Includes everything from beach or river pebbles to marble, granite, slate and modern day stone tiles. They have a wide range of colors, textures and surfaces. Also included are semiprecious stones - turquoise, lapis lazuli, alabaster, quartz and agate.

China & Porcelainshells for mosaic

A finer form of ceramics, they are a good source for interest, pattern and color.

Shells and Mother of Pearl

Mother of pearl is the lustrous inner surface of shells like oysters and abalone. Commonly used shell forms include spirals, scallops, snails, etc. and cover a wide range of color, luster and size.

asstorted items to mosaic withGlass

Includes mirror, colored glass, sea glass, glass nuggets, marbles, and pressed glass jewels

Everything Else

Bone, metals, buttons... just about anything you want can become tesserae in your mosaic.

This article concentrates primarily on using the mold or ‘stone’ method. Where applicable, we will include details for the method of applying the design to a paper type backing and setting into a prepared base.

Selecting the Base

items you can apply mosaic toYou can apply a mosaic to nearly any surface. When opting for the indirect method your want to end up with a very flat, even surface and this generally means the application or location of your mosaic dictates this. Examples include floors, table tops, bird baths, fountains, stepping stones, and counter tops. While gently curving surfaces accommodate this method, like the bowl of a bird bath, surfaces with a tight curves and turns won’t allow you to properly seat the design while attached to the removable base. In this case, the direct method is much more accommodating. When selecting a base think about the following:

Surfaces and items commonly used with the indirect method include but are not limited to:

 

Backing Material for Tesserae

The removable backing is what the individual pieces of the design are stuck to. The design is then cast in a mold or applied to the prepared surface of your mosaic base. The backing needs to be able to hold the tesserae securely enough but also allow for easy removal once the design is embedded or cast. Some backing require you apply the adhesive to the tesserae and others are self-stick. Common backing include:

 

Basic Tools

Beside a base, tesserae, and adhesive the only tool you'll really need to start with is a tile nipper. All other tools can be commandeered household items. As you work with different tesserae, bases, and adhesives you will find it useful to add specific tools to your arsenal.

Cutting Tools are used to shape and trim your tesserae

Containers

For holding your sorted tesserae, mixing cement and grouts, adding color, and holding water for cleaning. Save those containers you were about to throw out! You may not want to clean out that cement or grout container.

mosaic tools for pushing and spreadingAdhesive Spreaders

Depend on personal choice and the adhesives. Trowels of different sizes and types are useful for cement-based adhesives. For small work plastic spatulas, butter knives, and palette knives work well. PVA and epoxy bases can be applied with plastic spreaders, old brushes, toothpicks, wooden sticks, etc.

Grout Spreaders

Help push the grout over the mosaic and into the spaces between tesserae. They need to be flexible so as not to scratch the surface. Plastic spatulas, squeegees, grout floats, or even gloved hands will work.

Tools for Pushing and Prodding

Are handy for moving pieces into place and scraping out excess mortar or grout. Wooden sticks, wooden scrapers, tweezers, dental probes, toothpicks, awls, wooden clothes pins, pencils, and manicure tools are just some of the choices.

safety equipmentSafety Equipment must include.

mosaic grout and grouting toolsCement

Grout

Cleaning Articles

Are needed for wiping off excess grout and general tidying up. Lint free rags, sponges, and non-scratch nylon scouring pads are quite useful.

Lets Get Started

sizing the adhesive back for a mosaicSizing the Adhesive Backing
It is important for the adhesive backing to fit exactly inside the mold. If it is to large it will wrinkle and cement will seep under; too small and you will have a line in the finished surface. If you frequently use a particular size mold, you may want to make a template. A template also is a valuable sizing guide when designing and laying out a pattern specifically designed for the mold you are using.

Designs and Patterns
Inspiration comes from everywhere: nature, cities, surfaces, feelings, dreams, pattern books, magazines, and the list goes on. The choice is entirely up to you. You can go from totally abstract to precisely planned. Sketching out a basic cartoon can help you to solidify your idea, as well as to plan for color and movement. You may want to use (or modify) an existing pattern. There are many published patterns already designed to fit a particular shape mold. You can also design your own pattern. Use the template as a guideline for size and margins. Either way, once you have your design finalized, you need to have 3 copies: The original design to use as a reference and layout guide when cutting the tesserae. A second to cut up for pattern pieces. The third will be for assembly in the mold and needs to be the reverse of the original. When creating the pattern copies keep in mind:

  1. Trace the design onto the film (non-sticky) side of the adhesive paper while it is still attached to the paper backing. Don’t forget to mark edge allowances. When you separate the film for assembly, your design will be upside down.
  2. When making your final working copies, use tracing paper (or similar translucent paper) for the assembly copy. You can then tape this reversed side up to the film side of your adhesive backing. Your numbers will be backward, but it is still relatively easy to see where pieces go. You will remove this before casting the project in cement

Selecting Colors
Once you have a design, you will need to fill it with color. Choose what you like! Layout your tesserae and play with different combinations. Lay them on your design to see how they work and look. Keep in mind that each unit is a unit of color, texture, size, form and brilliance. How they play off each other will affect your design.

Be aware when choosing tesserae that they are backed by color of the cement. If you are using translucent or clear tesserae, their color will be affected by the color of the cement you are casting the design in. There are reflective tapes that you can apply to the back side of your tesserae to block the back ground cement color and reflect the transmitted light. Follow the manufacturers instructions for applying them to your tesserae.

Remember that the viewers eye will mix the shapes and colors in your design. Instead of covering a large area with the same tile, vary the shades used to add interest (unless the effect you want is a uniform block of color!). Grade (transition) colors into each other by varying the size and shape as they meet each other. Mix pieces of differing colors together. Place opposite colors next to each other for contrast. Make black or gray lines to accent or separate design elements or colors. Take advantage of patterns and colors in your tesserae. Play, experiment, stand back, look, rearrange, change, stand back, look...until you are satisfied. Again, do what you like and once you get started don't be afraid to change or deviate as the project unfolds.

Cutting the Tesserae: With any new technique or tool it is a good idea to practice on scrap materials (before you attack that one piece of really unique china you have). Work in a protected, covered, easy to clean area; you'll be creating shards and stray pieces that can cut the unsuspecting visitor. WEAR SAFETY GOGGLES! You can cut all your pieces ahead of time and lay them out on your cartoon or base; or you can work on the fly - cutting and fixing as you go. The choice is yours and depends on the complexity of the design, shape of the base, and the adhesive used.

Fixing the Design to the Adhesive Film or Backing
Once you have all the tesserae cut, fitted and are satisfied with your layout, you will need to transfer your design onto the adhesive backing, front side down.

LAYOUT THE DESIGN

FINAL LAYOUT

REVERSING THE PIECES

Preparing the Mold or Mortar Bed
Spray the mold bottom and sides with a release agent. There are several commercially available, check with your supplier. Vaseline® is used by some. Apply liberally with a sponge brush and then use a hair dryer to smooth. You don’t want any ridges. Then tip the mold and gently slide the adhesive sheet with your design into position in the mold. Check your tesserae one last time. Also make sure the edge of the adhesive film is lying flat in the mold bottom and not curving up the sides.

Since paper backed projects are pressed into a prepared bed of mortar, you need to prepare the surface and then apply the mortar according to the manufacturers instructions.

Mixing and Pouring the Cement
Mix your cement according to manufacturer's instructions. Generally you combine all dry ingredients in a large enough container to accommodate them and give you room to thoroughly mix them. If you are coloring your cement add the colorant to the dry ingredients and mix well. Take a small sample and mix with liquid to test the color. Color in cement fades as it cures. A general rule of thumb is to mix the color 2 shades darker than the finished color you want. Save a small amount (1/2 cup or so) of the final dry mix to use for filling in any gaps or pinholes you find after you un-mold the project. The liquid is then added to the dry ingredients and mixed. Be aware that as you mix, you want to avoid introducing air bubbles. Check the manufacturers instructions for consistency, some cements are mixed to a medium oatmeal, some more like brownie batter.

It is best if you can pour the concrete into the form in the place you intend to leave it to cure. It is risky on several levels to move a mold filled with cement. Make sure the mold sits level. Start by pouring a thin layer around the edges to help hold the adhesive film down. Cover the bottom with a thin layer and then gently pat the top or tap the mold to release any bubbles and work the cement down between the tesserae. Continue filling the mold until you reach the top or your desired thickness. You don’t have to fill the mold to the top but the thinner the concrete, the weaker your project will be.

You want to ‘screed’ or level the surface by taking a piece of wood or similar item that will span the width of the mold and draw it across the top to level and remove any excess cement. Wipe the edge/lip clean. Again, tap your mold edge and sides gently for a few minutes to release any bubbles. Some people also tap the surface the mold is sitting on. Be careful, this is more apt to dislodge the tesserae from the adhesive backing. Allow the mold to sit undisturbed for the required amount of set time, based on manufacturers instructions.

In a paper backing project, gently press the mosaic into the bed, paper side up. Allow the cement to set enough to hold the design in place so you can remove the paper but not so tight that you can’t make any needed adjustments.

allow the stone to cureUn-molding the Project
You need to now release the project from the mold

Grouting an Embedded Design
Grouting is the technique of filling in the spaces between your tesserae. If you used the paper fixing method and then set your design into a motor or cement bed, you will need to fill in the gaps, or grout, between your tesserae after removing the paper baking. Generally, it is desirable to make the grout level with the overall height of the mosaic surface. Grout is just a fine textured version of cement mortar. It unifies the design. Its color enhances the design: and it adds strength. 

Sealing and Protection
Some materials and applications benefit from an application of sealant after the project has cured or the grout is dried and cured. You also want to protect your finished project from the elements.

now step back and admire your work!  mosaic stepping stone path   

Resources

There are variations on the technique presented here and many excellent book resources (see below) to help you expand your knowledge and creativity. As you experiment and work with different materials you will discover what methods, tools, and supplies work best for you!
Ancient Mosaics
by Roger Ling Paperback
Princeton University Press
Paperback / 1998 / 144pp
ISBN: 0691004048
The Art of Mosaics
by Joaquim Chavarria
Watson-Guptill Publishing
Paperback / 1999 / 160 pp
ISBN: 0823058646
The Art of Mosaic Design: A Collection of Contemporary Artists
by J.Locktov - L.P.Clagett
Rockport Publishing
Hardcover / 1998
ISBN: 1564964205
Backyard Mosaics
by Connie Sheerin
Sterling Publishing
Hardcover & Paperback / 2001 / 128 pp
ISBN: 0806929677
Classic Mosaics
 by Elaine M Goodwin
Trafalgar Square Publishing Ltd.
Hardcover / 2000 /  144 pp
ISBN 1570761590
Encyclopedia of Mosaic Techniques (Encyclopedia of Art Techniques)
by Emma Biggs
Penguin USA
Hardcover / 1999 / 160 pp
ISBN: 0762404442
Making Mosaics
by Leslie Dierks
Sterling Publishing Co.
Hardcover / 1998 / 128 pp
ISBN: 0806948728
Mosaics
by Kaffe Fassett & Candace Bahouth
Taunton Books & Videos
Hardcover / 1999 / 160 pp
ISBN 1561583731
The Mosaic Book : Ideas, Projects and Techniques
by Peggy Vance, Celia Goodrich-Clarke
Trafalgar Square Publishing Ltd.
Paperback / 1996 / 128 pp
ISBN: 1570760608z
Mosaic Workshop : A Guide to Designing and Creating Mosaics
by Emma Biggs, Tessa Hunkin
Trafalgar Square Publishing, Ltd.
Hardcover / 1999 / 128 pp
ISBN: 1570761493

koi mosaic stone sundail
from Mosaic Sundials / M. Koehl