I'm marble tiles, Xiuyuan Xiyuan, Lishui District, and I'm a home decorator. When I post it, I'll tell the store if I find the color difference. What should I do if the gray color has turned reddish after the paste is finished? Ceramic tiles are divided into five grades, which are superior, first-class, second-class, third-class and off-grade. Due to the large price difference, they need to be carefully compared. When purchasing, pay attention to whether the identification, specification and color number on the ceramic tile and the packing box are consistent, and whether the product certificate, trademark and quality inspection label are clear. Products with dimensional error greater than .5 mm and flatness greater than .1 mm will not increase the difficulty of construction, and the effect after decoration is also poor. Whether the size meets the standard can be judged by visual inspection. Put the brick on a flat surface to see if its four edges are completely consistent with the flat surface, and at the same time, see if the four corners of the tile are right angles. Ceramic tiles should be free from defects such as concave-convex, bulging and warpage, and the error of side length should not exceed .2-.3mm, and the error of thickness should not exceed .1mm.. (Detailed data should be proofread by vernier caliper) Ceramic tiles have good hardness, strong toughness and are not fragile and rotten. Scratch each other with the edges and corners of ceramic tiles to see whether the broken fragments are fine or loose, hard, brittle or soft, leaving scratches or scattered powder. If the former is top grade, the latter is poor quality. A good ceramic tile printing process has the advantages of clear and consistent patterns and patterns, exquisite process, and no obvious color leakage, dislocation, broken line or inconsistent depth. The color of ceramic tiles should be uniform, the surface smoothness and flatness should be good, the periphery should be regular, and the pattern should be complete. Take out four or five pieces from a box to see if there are any defects such as color difference, deformation, lack of edges and corners. You can drop water on the back of the tile to see the speed of infiltration after the water is dispersed. Generally speaking, the slower the water absorption, the greater the density of the tile; On the contrary, the faster the water absorption, the sparse density, and its internal quality is better than the former. Usually, cheap tiles will spread some uneven black spots when the tiles are not harmonious, especially the color contrast is deep and the color distribution is uneven, which is because these tiles are not cleaned after removing impurities and iron.