When starting a tile project, I always wipe each tile off with a clean soft cloth. This removes all the dust and particles that accumulate while packed in the case. If there are stains that you aren't sure what are, you can always fire the tile before working on it. This should remove the stain.
Pick a pattern that isn't too complicated. It isn't easy to get glaze into tiny areas. I transfer the pattern with carbon paper or you can also freehand a pattern with a pencil. I usually lay a piece of paper over the area of tile I'm not working on so I don't smear the pattern with my hand.
There are a few ways to outline your pattern. You can use wax or wax resist. Both of these methods will let the color of the tile show through when fired. If you want it outlined in black, use the Waxline pen or you mix Duncan's EZ012 Cobalt Jet Black and wax resist. This is mixed to a brushing consistency and used to outline the pattern. I always apply this with a brush. This mixture repels the glaze and holds it in place when firing.
The glaze is applied with squeeze bottles. This requires only one even coat instead of three when brushing glaze on. If the glaze seems to be a little thick to apply out of a bottle, add a few drops of water to thin. It may be necessary to use a pin tool, nail, or whatever to push the glaze into small areas that cannot be reached by the bottle tip. You can use any Duncan or Mayco glaze that is for cone 06 and is opaque. Translucent glazes don't work well. We especially like Duncan's Concepts as they come in smaller jars and there are hundreds of colors.
Two or more glazes can be blended in one area by applying the colors and before they dry, pushing them together. This works well when doing flowers or anything that wouldn't be just one solid color. It kind of gives a marbleizing effect. When the glazes are dried, fire the tiles to cone 06. After firing, the tile can either be framed, put on the wall with grout, or however you choose to decorate with them.
Now that you have mastered making tiles, let's do a mural for the wall. Be sure to have a pattern that will fit the area that you have in mind. It will be helpful to lay out the finished tiles so you don't put the design up in the wrong place.
The first thing you need to do is find the center of the wall. Mark it with a chalk line from top to bottom and from side to side. This will give you a plus sign in the middle of the wall. When you put the tiles on the wall, it is best to work from center out to avoid not having your pattern off center.
You will need to mix up thin set cement. Just mix up enough for the immediate area that you are working on. If it starts to dry out, it becomes hard to work with. It is best to use a tool that has ridges to apply the thin set to the back of the tiles. This is called buttering the tiles. Make sure to get good coverage on the back of the tile before applying to the wall. Be sure to line up the tile with the chalk line. Most tiles have tabs on the sides for correct spacing. If need be , you can buy tile spacers or even use pennies.
Nails can be nailed at an angle under the tiles to hold them in place. If working in a large area, you can nail a one by two board across the entire length of the wall and rest the tiles on the board. Let the thin set cure for twenty four hours before removing the nails and or board.
You are now ready to apply the grout. The easiest way to do this is with your fingers. Mix the grout to a dough like consistency. Always wear latex gloves so the pigment in the grout doesn't absorb into your skin. Take a good size glob of grout and press in between the tiles being sure to get a good coverage. It is always a good idea to work an area then go back and clean the grout off the tiles with a damp sponge before it completely dries. After putting grout on the whole project, let the grout set up for at least twenty four hours. At this time, you can seal the grout. This isn't necessary if the mural isn't on a wall that is subject to the weather.
Now you have a wall that will be the envy of your friends and family. Be prepared to have requests to do one at their homes.
Have fun and enjoy!