Ceramic tiles are divided into five grades, including high-quality products, first-class products, second-class products, third-class products and out-of-class products. Due to the large price difference, careful comparison is required. When purchasing, pay attention to whether the logos, specifications, and color numbers on the ceramic tiles and packaging boxes are consistent, and whether the product certificate, trademark, and quality inspection label are clear. Products with dimensional errors greater than 0.5 mm and flatness greater than 0.1 mm will not only increase the difficulty of construction, but also result in poor decoration results. Whether the size meets the standards can be judged visually. Place the brick on a flat surface to see if its four sides are completely consistent with the flat surface. At the same time, see if the four corners of the tile are all right angles. Ceramic tiles should be free of defects such as bumps, bulges, and warped corners. The error in side length should not exceed 0.2---0.3 mm, and the error in thickness should not exceed 0.1 mm. (Detailed data should be calibrated with a vernier caliper) Ceramic tiles should have good hardness, strong toughness, and not easily broken. Use the edges and corners of the tile fragments to scratch each other to see if the broken fragments are fine or loose, hard, brittle or soft, leaving scratches or scattered powder. If the former is the top grade, the latter is the quality. Difference. A good ceramic tile printing process will have clear and consistent patterns and colors, delicate and exquisite workmanship, and no obvious color leakage, misalignment, disconnection or inconsistent depth. The color of the ceramic tiles should be uniform, the surface finish and flatness should be good, the perimeter should be regular, and the pattern should be complete. Take four or five pieces out of a box and inspect them for defects such as color difference, deformation, missing edges and corners. You can drop water on the back of the ceramic tile to see how fast the water soaks after it spreads. Generally speaking, the slower the water absorption is, the greater the density of the ceramic tile is; conversely, the faster the water absorption is, the sparse density is, and its intrinsic quality is superior to the former.

Usually cheap ceramic tiles will have some uneven black spots scattered throughout the ceramic tiles, especially the deep color contrast and uneven color distribution. This is because these ceramic tiles have not removed impurities and iron.