Interior wall tiles are a type of ceramic tiles, primarily used for indoor wall decoration. They consist of three parts: the body, the underglaze layer, and the glaze layer. The water absorption rate of the body is generally around 10-18%. The weight of the underglaze is typically 40-60 grams, while the surface glaze is 90-160 grams. In general, the higher the firing temperature, the greater the surface glaze weight, resulting in better luster and a smoother surface for the tile. Of course, the quality of the glaze also has a significant impact.

Inspection Standards: 1. For wall tiles, it is not permitted to have hollow spots in any area. Hollow spots at the edges of tiles are allowed, but the total number of hollow spots in one room should not exceed three. You can use this standard to inspect the wall tiles in our indoor kitchen and bathroom.

2. The standard for perpendicularity is that the verticality of the tile's face must be controlled within 3mm. Otherwise, it is not qualified.

3. The standard requirement for flatness is that the tiles must not exceed a 2mm tolerance for flatness, and the difference in height between adjacent tiles should not exceed 0.5mm. Tiles exceeding the tolerance are considered defective, and we can request them to be removed and re-laid.

4. The level or verticality error in tile joints should not exceed 0.5mm. In fact, it's visible to the naked eye if it does. Additionally, measure the vertical and horizontal levels of tile joints before applying the grout, as the grout can cover them up, making it difficult for us to measure later.