sometimes, installation of mosaic tile for backsplash can be tricky. Tile installations made with mosaic tiles offer a great way to add visual interest to a room. Whether used for floors, walls, counters or backsplashes, tile, porcelain or glass mosaics create sophisticated design effects that add a touch of luxury to any room. Historically, mosaics were originally carefully applied as small individual tiles to create uniformly large surfaces with intricate patterns, but modern mosaics consist of convenient pre-applied tiles that are very easy to install. For very small tiles or geometrically shaped tiles, mosaic panels have advantages over using ceramics or individual tiles. Modern mosaic tile is a product in which smaller tile squares (usually 2 square inches or less) are glued to mesh fiberglass panels. The tiles are spaced across the sheets so that the spaces between the tiles are just the right width for the grout joints. This allows mosaic tiles to be installed much faster than using small individual tiles.
The mosaic pieces can be composed of tiles of the same color or tiles of different colors and shapes to achieve the design effect. Most mosaic panels are traditional tiles, but there are also mosaics that use ceramic tiles, glass tiles, natural stone, and even unglazed terracotta. For this reason, the cost of mosaic tiles can vary greatly depending on the material. Mosaic panels are usually made of small square tiles, but some mosaics are made of small rectangular tiles or other geometric shapes. They can even mix different shapes on the same sheet. There are also narrow mosaic tiles for borders and other accent applications. The mosaic tile installation technique is almost the same as standard tile, but sometimes cutting is easier because installing part of the sheet can be as simple as cutting the fiberglass backing to create a custom shape sheet.
- Prepare the surface
As with any tile installation, the mosaic tile surface should be completely flat and smooth. In modern tiling jobs, the sheathing is usually a cement board applied over a plywood sub floor or directly against the wall studs. Mosaic tiles can be laid directly over plywood or wallboard (in non-wet locations), but cement board provides the best support and is the professional's first choice. Install the entire cement board first, then cut the pieces to fit the remaining space.
The cement board is best cut with a sharp knife, guided by the carpenter's steel frame square, and then broken along the score line. Use cement board screws to fasten the boards to the studs with the rough side of the boards facing out. Leave approximately 1/8" gap between panels. Cover the seams between the cement board panels with 2" wide fiberglass cement board tape, then cover the tape with a thin layer of adhesive and apply with a taping knife. If you're installing tile over plywood or drywall, use latex adhesive instead of thin-set mortar.
- Plan the Tile Layout
Proper installation with mosaic tile requires a carefully planned layout to ensure grout joints are perfectly square. Draw intersecting vertical layout lines that divide the surface from top to bottom and left to right. Most professionals begin installation in the center of the area, installing all the full tiles first, then making any necessary cuts around boundaries and obstructions.
- Attach the First Tile Sheet
Starting in the center where the layout lines intersect, use a notched trowel to apply a thin coat of adhesive to one of the layout quadrants, working in an area of approximately 2-3 square feet. Make sure not to over-apply the adhesive; you should be able to see the cement board at the bottom of the groove. 
Glue the first tile in the corner of the first quadrant and carefully adjust it by hand to make sure it is perfectly aligned with the plot line. Press firmly to insert the tile into the thin sleeve. Hold for a few seconds and watch for any slippage as you release hand pressure on the tile. Your tile and thin products will specify the size of the notched trowel to use. Some trowels use a v-shaped notch, while others use a square notch.
- Fill in the First Quadrant
Install adjacent mosaic panels in the first quadrant, in the same manner, using tile spacers to ensure that the spaces between the panels are exactly the same as the spaces between the tiles inside the panels. With mosaic sheets, the small tiles are staggered so that the sheets fit together. Make sure the grout joint remains even across the entire tile surface.
- "Set" the Tiles
Mosaic sheets behave differently from a single large tile; they can ripple or create waves on the surface. To prevent this from happening, use a small piece of plywood (about 8" square) and a rubber mallet to "set" the tiles by tapping the mosaic panels into the sheet after each installation. This will level the tiled area, giving it a smooth finish. Pay particular attention to the joints between the sheets to ensure that there are no cracks in the lips (a row of tiles higher than its adjacent row) or slippage (the gap between the sheets wider than the grout spaces in the sheets).
- Cut the Tile Sheets to Fit
As you get closer to the edge of the tiled area, you may need to cut the tile to size. In some cases, it is sufficient to cut the fiberglass mesh to create a partial sheet that is exactly the size you need, but in other cases, you may need to cut individual edge tiles for a precise adjustment.
Avoid this as much as possible; you can use recessed tile or other baseboard trim or molding to cover the gaps at the edges of the layout. To cut the sheets to size, simply use a sharp knife to cut the mesh backing along the grout joints. Install the cut tiles the same way as the whole sheet.
- Cut the Individual Tiles
If you need to cut individual tiles from a sheet, you have several options. Tile sheets can be fed through a tile wet saw in the same way as full-size tiles. This is by far the easiest way to cut tile and the best strategy for oversized tile installations that require a lot of cutting. Wet saws can be rented at home improvement centers and tool rental stores. Simple wet saws are relatively inexpensive and a good investment if you regularly do tile work. Another option is a simple hand tool called a tile nipper, which looks like a pair of modified pliers that can be used to "nibble" each individual tile square in the array. Alternatively, you can use an orbital knife (or slip knife, as it's sometimes called) to score entire rows of tiles. Each individual tile can then be inserted into the sheet, one at a time, using the tool's swivel bar. Another option for cutting tile is a 4 1/2-inch grinder equipped with diamond wheels.
- Complete Installation on the Remaining Quadrants
After completing one quadrant of the collage job, repeat the above steps to complete the other three quadrants, one at a time. For each quadrant, work outward from the center point of the layout towards the edges.
- Install the Trim Tiles
Complete the installation by installing any trim or accent tiles you are using. This can include rounded edges, recessed tiles or skirting tiles. These can also be applied using thin adhesives. After all tiles are installed, allow the installation to cure a little before continuing with grouting.
- Mix the Grout
After the mosaic tiles are properly cured into a fine shape and there is no risk of shifting, mix a batch of grout with dry powder (or you can use pre-mixed grout for small work). In general, use unsanded grout for grout joints 1/8 inch or smaller and sanded grout for larger joints. 1 Mix according to manufacturer's instructions.
- Apply the Grout
Load the edge of the rubber grout float with grout, then spread the grout on top of the tile. Using several passes of the grout float, force the grout into the joint so that the float is at a 45 degree angle to the surface. The edge of the float is what forces the grout deep into the joint. You will need to change the direction of the grout float to ensure that the grout completely fills all joints. Proceed until all joints are filled with grout. For mosaic tiles, this can be a lengthy process as there are many grout joints. Use the edge of a grout float to scrape excess grout from the tile surface.
- Clean the Tile Surface
Allow the grout to harden slightly according to the manufacturer's instructions, then wipe the surface of the tile with a clean cloth to remove the dry grout. Once the grout has fully cured (again, according to the manufacturer's instructions), use a liquid grout defogger to remove any remaining grout film.
- Seal the Grout Lines
Because tile grout is porous, it must be sealed to protect the underlayment, as well as the integrity of the grout. This is especially important in humid places, such as showers. Use any type of sealer recommended by the grout manufacturer and wait until the grout is completely dry and hardened before applying it. For mosaic tile and its many grout lines, the easiest way to apply a sealer is to brush or roll over the entire surface. When the surface begins to dry, wipe off any excess sealer from the tile surface; it penetrated the grout. Most sealants recommend two applications for the initial seal, followed by additional applications every one to two years.