When you shop Tile , you will find rectified porcelain tile. Although the term 'rectified' can be confusing, it simply refers to a tile where the edges have been ground or sawed after firing so that the overall size of the tile is more precise or exact. TEXING TILES are rectified  tile meaning that they have been cut during the manufacturing process to meet exact size requirements. Rectification happens after the tiles are fired. That's because for both porcelain and ceramic tiles the firing process can create up to a 1.5% variation in size.  This is normal and taken into account during the installation process. By sawing, machining or precisely grinding the tiles after firing, the manufacturer tries to minimize (or rectify) the size variations from tile to tile. The two images below show you an up-close look at a pressed tile (i.e., "normal") where you can see the variations in the edges, and a rectified tile. The two images below show you an up-close look at a pressed tile (i.e., "normal") where you can see the variations in the edges, and a rectified tile. This is the pressed tile close-up. In the image below, notice how clean, precise and exact the edges look. Notice, too, the back of the tile and how you can see where it was mechanically cut and/or ground after the firing of the tile. Rectification is Considered an Edge Treatment for Tile Because the grinding or sawing happens to the edges of the tile, rectification is considered an edge treatment. It does not affect the thickness of the tile. Furthermore, it does not make a tile better or worse. Rectification simply affects the kind of edges the tile has which, in turn, means that rectified tile is ideal for specific types of tile installation. These next two images focus on the back of the tile. The first non-rectified or pressed tile back has a regular border around the edges.