QUESTIONWe are having glass tile installed in our shower. The tile is clear with white at the back. We are noticing that the edges of the tile as installed and grouted are not a uniform color. They within the same tile there are areas of light and dark. The shower has been used and the discoloration seems to be worse after shower use, but it is there all the time. I'm looking to see if the tile was installed properly.
ANSWERANSWER - Some translucent glass tiles are coated with a white coating so that you can't see the conditions under the glass tile. When there isn't a white coating on the back of the glass tile, then the installer has to make sure the thin-set mortar adhesive is a uniform color and that the thin-set mortar is applied with continuous flat manner. Otherwise you can see the difference in color of the thin-set mortar and any voids in the thin-set mortar with translucent glass tiles.
You say that the edges of the glass tile, after it is grouted, are not uniform in color, and that the discoloration worsens when the shower is used. I'm assume that you are saying that the top side/edge of the glass tile is visible. So maybe there are some voids along the edges of those class tiles that fill with water after the shower is used and that is what you are seeing?
Maybe you are describing that grout that has color variation. It is normal for cementitious grouts to have some grout color variation when dry and wet.
Either way this condition may or may not be considered a problem depending on whether there are any resultant damages caused by the condition other than aesthetic concerns. Glass tile mosaics are normally a fairly irregular material dimensionally, so it tends to have many more imperfections which gives it its character. The larger modular glass tiles are more consistent, but still has variations.
These tiles are installed in a craftsmanship manner so there will be inconsistencies in the installation, which is inherent in the material and process. Of course there can be poor workmanship that results in variations that are excessive.