Why black after finishing grouting?

Finishing grouting found depression in ceramic tile, looks black, what is the reason?

First, the construction problem

1. Grouting is the key, some people in order to save material, glue is not full enough, only on the surface of the ceramic tile gap, although the joint is flat only a thin layer, over a long time, will naturally fall off, sag down.

2. Some inexperienced tilers, because they are not professional enough, exert uneven force when gluing. Some places have more glue and some have less glue, which will also lead to the subsequent sag. Also because the joint is too much, resulting in the tile grout to make the joint is not beautiful.

3. Kelin plastic two-component real porcelain glue factory all shall implement the construction method of "full filling", especially the joints of floor tiles. Because this construction method can not only create a perfect construction effect, the surface of grouting is smooth after pressing the joint, and there will be no depression in the follow-up.

Two, the quality of tile grout

1. The use of inferior tile grout, the quality is not up to standard, and the raw materials are jilted, resulting in very sparse joint materials. Not only will the wall flow on the glue, but also there will be collapse.

2. The inferior tile grout allows the use of cheap pigments, easy to change color, fall off, and soon will blacken and crack.

The above is the reason why the tile grout sags and turns black. Do you understand all of them?