Required for the installation of tile ranging from tiny mosaics to large limestone tile, thinset comes in two colors: white or gray. The color of thinset is determined by the type of cement used during the manufacturing process; white cement is used in white thinset; gray cement in gray; both colors perform identically. In many cases, the color of thinset does not matter. Nevertheless, in some instances the do-it-yourselfer's choice of material determines the color of thinset required for the job.
Glass Mosaic Tile
Due to their translucent or completely transparent properties, mosaic tiles require installation with white thinset. If installed with gray thinset, the coloring of mosaics will change drastically. On the other hand, white thinset does not alter the look and color range of glass mosaic tile.
Travertine and Porous Natural Stone
Limestone such as travertine is very porous and stains easily. For this reason, experts recommend the use of white thinset in installing porous stone. Take note that white thinset can still stain the most porous varieties of limestone.
Slate tile is typically less porous than travertine and has a dark-colored body. For this reason, gray thinset is recommended. White thinset may prove to be difficult to clean off the surface and small cracks on the finished surface area of slate; gray thinset eliminates this risk.
Granite tile is extremely dense and impervious to staining during installation, therefore either gray or white thinset are appropriate, although the do-it-yourselfer may want to choose the thinset color that is the closest in color range to his selected grout color.
Ceramic and Porcelain Tile
Ceramic and porcelain tile share a common characteristic: it does not matter whether you install them with either gray or white thinset. Often the choice of thinset color simply comes down to the grout color selection. For instance, if you are installing granite tiles and have selected a gray-toned grout color, gray thinset is a good choice for installation. If the thinset shows through the grout, it will be less noticeable.